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lua-nginx-module

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openresty /lua-nginx-module

Embed the Power of Lua into NGINX HTTP servers

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Name

ngx_http_lua_module - Embed the power of Lua into Nginx HTTP Servers.

This module is a core component of OpenResty. If you are using this module, then you are essentially using OpenResty.

This module is not distributed with the Nginx source. Seethe installation instructions.

Table of Contents

Status

Production ready.

Version

This document describes ngx_luav0.10.17, which was released on 3 July, 2020.

Synopsis

# set search paths for pure Lua external libraries (';;' is the default path): lua\_package\_path '/foo/bar/?.lua;/blah/?.lua;;'; # set search paths for Lua external libraries written in C (can also use ';;'): lua\_package\_cpath '/bar/baz/?.so;/blah/blah/?.so;;'; server { location /lua\_content { # MIME type determined by default\_type: default\_type 'text/plain'; content\_by\_lua\_block { ngx.say('Hello,world!') } } location /nginx\_var { # MIME type determined by default\_type: default\_type 'text/plain'; # try access /nginx\_var?a=hello,world content\_by\_lua\_block { ngx.say(ngx.var.arg\_a) } } location = /request\_body { client\_max\_body\_size 50k; client\_body\_buffer\_size 50k; content\_by\_lua\_block { ngx.req.read\_body() -- explicitly read the req body local data = ngx.req.get\_body\_data() if data then ngx.say("body data:") ngx.print(data) return end -- body may get buffered in a temp file: local file = ngx.req.get\_body\_file() if file then ngx.say("body is in file ", file) else ngx.say("no body found") end } } # transparent non-blocking I/O in Lua via subrequests # (well, a better way is to use cosockets) location = /lua { # MIME type determined by default\_type: default\_type 'text/plain'; content\_by\_lua\_block { local res = ngx.location.capture("/some\_other\_location") if res then ngx.say("status: ", res.status) ngx.say("body:") ngx.print(res.body) end } } location = /foo { rewrite\_by\_lua\_block { res = ngx.location.capture("/memc", { args = { cmd = "incr", key = ngx.var.uri } } ) } proxy\_pass http://blah.blah.com; } location = /mixed { rewrite\_by\_lua\_file /path/to/rewrite.lua; access\_by\_lua\_file /path/to/access.lua; content\_by\_lua\_file /path/to/content.lua; } # use nginx var in code path # CAUTION: contents in nginx var must be carefully filtered, # otherwise there'll be great security risk! location ~ ^/app/([-\_a-zA-Z0-9/]+) { set $path $1; content\_by\_lua\_file /path/to/lua/app/root/$path.lua; } location / { client\_max\_body\_size 100k; client\_body\_buffer\_size 100k; access\_by\_lua\_block { -- check the client IP address is in our black list if ngx.var.remote\_addr == "132.5.72.3" then ngx.exit(ngx.HTTP\_FORBIDDEN) end -- check if the URI contains bad words if ngx.var.uri and string.match(ngx.var.request\_body, "evil") then return ngx.redirect("/terms\_of\_use.html") end -- tests passed } # proxy\_pass/fastcgi\_pass/etc settings } }

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Description

This module embeds LuaJIT 2.0/2.1 into Nginx. It is a core component of OpenResty. If you are using this module, then you are essentially using OpenResty.

Since version

v0.10.16

of this module, the standard Lua interpreter (also known as "PUC-Rio Lua") is not supported anymore. This document interchangeably uses the terms "Lua" and "LuaJIT" to refer to the LuaJIT interpreter.

By leveraging Nginx's subrequests, this module allows the integration of the powerful Lua threads (known as Lua "coroutines") into the Nginx event model.

Unlike Apache's mod_luaand Lighttpd's mod_magnet, Lua code executed using this module can be 100% non-blocking on network traffic as long as the Nginx API for Lua provided by this module is used to handle requests to upstream services such as MySQL, PostgreSQL, Memcached, Redis, or upstream HTTP web services.

At least the following Lua libraries and Nginx modules can be used with this module:

Almost any Nginx modules can be used with this ngx_lua module by means ofngx.location.capture orngx.location.capture_multi but it is recommended to use those

lua-resty-\*

libraries instead of creating subrequests to access the Nginx upstream modules because the former is usually much more flexible and memory-efficient.

The Lua interpreter (also known as "Lua State" or "LuaJIT VM instance") is shared across all the requests in a single Nginx worker process to minimize memory use. Request contexts are segregated using lightweight Lua coroutines.

Loaded Lua modules persist in the Nginx worker process level resulting in a small memory footprint in Lua even when under heavy loads.

This module is plugged into Nginx's "http" subsystem so it can only speaks downstream communication protocols in the HTTP family (HTTP 0.9/1.0/1.1/2.0, WebSockets, etc...). If you want to do generic TCP communications with the downstream clients, then you should use thengx_stream_luamodule instead, which offers a compatible Lua API.

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Typical Uses

Just to name a few:

  • Mashup'ing and processing outputs of various Nginx upstream outputs (proxy, drizzle, postgres, redis, memcached, and etc) in Lua,
  • doing arbitrarily complex access control and security checks in Lua before requests actually reach the upstream backends,
  • manipulating response headers in an arbitrary way (by Lua)
  • fetching backend information from external storage backends (like redis, memcached, mysql, postgresql) and use that information to choose which upstream backend to access on-the-fly,
  • coding up arbitrarily complex web applications in a content handler using synchronous but still non-blocking access to the database backends and other storage,
  • doing very complex URL dispatch in Lua at rewrite phase,
  • using Lua to implement advanced caching mechanism for Nginx's subrequests and arbitrary locations.

The possibilities are unlimited as the module allows bringing together various elements within Nginx as well as exposing the power of the Lua language to the user. The module provides the full flexibility of scripting while offering performance levels comparable with native C language programs both in terms of CPU time as well as memory footprint thanks to LuaJIT 2.x.

Other scripting language implementations typically struggle to match this performance level.

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Nginx Compatibility

The latest version of this module is compatible with the following versions of Nginx:

  • 1.17.x (last tested: 1.17.8)
  • 1.15.x (last tested: 1.15.8)
  • 1.14.x
  • 1.13.x (last tested: 1.13.6)
  • 1.12.x
  • 1.11.x (last tested: 1.11.2)
  • 1.10.x
  • 1.9.x (last tested: 1.9.15)
  • 1.8.x
  • 1.7.x (last tested: 1.7.10)
  • 1.6.x

Nginx cores older than 1.6.0 (exclusive) are not supported.

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Installation

It is highly recommended to use OpenResty releaseswhich bundle Nginx, ngx_lua (this module), LuaJIT, as well as other powerful companion Nginx modules and Lua libraries.

It is discouraged to build this module with Nginx yourself since it is tricky to set up exactly right.

Note that Nginx, LuaJIT, and OpenSSL official releases have various limitations and long standing bugs that can cause some of this module's features to be disabled, not work properly, or run slower. Official OpenResty releases are recommended because they bundle OpenResty's optimized LuaJIT 2.1 fork andNginx/OpenSSL patches.

Alternatively, ngx_lua can be manually compiled into Nginx:

  1. LuaJIT can be downloaded from the latest release of OpenResty's LuaJIT fork. The official LuaJIT 2.x releases are also supported, although performance will be significantly lower for reasons elaborated above
  2. Download the latest version of the ngx_devel_kit (NDK) module HERE
  3. Download the latest version of ngx_lua HERE
  4. Download the latest supported version of Nginx HERE (See Nginx Compatibility)

Build the source with this module:

wget 'https://nginx.org/download/nginx-1.13.6.tar.gz' tar -xzvf nginx-1.13.6.tar.gz cd nginx-1.13.6/ # tell nginx's build system where to find LuaJIT 2.0: export LUAJIT\_LIB=/path/to/luajit/lib export LUAJIT\_INC=/path/to/luajit/include/luajit-2.0 # tell nginx's build system where to find LuaJIT 2.1: export LUAJIT\_LIB=/path/to/luajit/lib export LUAJIT\_INC=/path/to/luajit/include/luajit-2.1 # Here we assume Nginx is to be installed under /opt/nginx/. ./configure --prefix=/opt/nginx \ --with-ld-opt="-Wl,-rpath,/path/to/luajit/lib" \ --add-module=/path/to/ngx\_devel\_kit \ --add-module=/path/to/lua-nginx-module # Note that you may also want to add `./configure` options which are used in your # current nginx build. # You can get usually those options using command nginx -V # you can change the parallism number 2 below to fit the number of spare CPU cores in your # machine. make -j2 make install

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Building as a dynamic module

Starting from NGINX 1.9.11, you can also compile this module as a dynamic module, by using the

--add-dynamic-module=PATH

option instead of

--add-module=PATH

on the

./configure

command line above. And then you can explicitly load the module in your

nginx.conf

via the load_moduledirective, for example,

load\_module /path/to/modules/ndk\_http\_module.so; # assuming NDK is built as a dynamic module too load\_module /path/to/modules/ngx\_http\_lua\_module.so;

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C Macro Configurations

While building this module either via OpenResty or with the Nginx core, you can define the following C macros via the C compiler options:

  • NGX\_LUA\_USE\_ASSERT
    When defined, will enable assertions in the ngx_lua C code base. Recommended for debugging or testing builds. It can introduce some (small) runtime overhead when enabled. This macro was first introduced in the
    v0.9.10
    release.
  • NGX\_LUA\_ABORT\_AT\_PANIC
    When the LuaJIT VM panics, ngx_lua will instruct the current nginx worker process to quit gracefully by default. By specifying this C macro, ngx_lua will abort the current nginx worker process (which usually result in a core dump file) immediately. This option is useful for debugging VM panics. This option was first introduced in the
    v0.9.8
    release.

To enable one or more of these macros, just pass extra C compiler options to the

./configure

script of either Nginx or OpenResty. For instance,

./configure --with-cc-opt="-DNGX\_LUA\_USE\_ASSERT -DNGX\_LUA\_ABORT\_AT\_PANIC"

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Community

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English Mailing List

The openresty-en mailing list is for English speakers.

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Chinese Mailing List

The openresty mailing list is for Chinese speakers.

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Code Repository

The code repository of this project is hosted on GitHub atopenresty/lua-nginx-module.

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Bugs and Patches

Please submit bug reports, wishlists, or patches by

  1. creating a ticket on the GitHub Issue Tracker,
  2. or posting to the OpenResty community.

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LuaJIT bytecode support

As from the

v0.5.0rc32

release, all

\*\_by\_lua\_file

configure directives (such as content_by_lua_file) support loading LuaJIT 2.0/2.1 raw bytecode files directly:

/path/to/luajit/bin/luajit -b /path/to/input\_file.lua /path/to/output\_file.ljbc

The

-bg

option can be used to include debug information in the LuaJIT bytecode file:

/path/to/luajit/bin/luajit -bg /path/to/input\_file.lua /path/to/output\_file.ljbc

Please refer to the official LuaJIT documentation on the

-b

option for more details:

https://luajit.org/running.html#opt_b

Note that the bytecode files generated by LuaJIT 2.1 is not compatible with LuaJIT 2.0, and vice versa. The support for LuaJIT 2.1 bytecode was first added in ngx_lua v0.9.3.

Attempts to load standard Lua 5.1 bytecode files into ngx_lua instances linked to LuaJIT 2.0/2.1 (or vice versa) will result in an Nginx error message such as the one below:

[error] 13909#0: \*1 failed to load Lua inlined code: bad byte-code header in /path/to/test\_file.luac

Loading bytecode files via the Lua primitives like

require

and

dofile

should always work as expected.

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System Environment Variable Support

If you want to access the system environment variable, say,

foo

, in Lua via the standard Lua API os.getenv, then you should also list this environment variable name in your

nginx.conf

file via the env directive. For example,

env foo;

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HTTP 1.0 support

The HTTP 1.0 protocol does not support chunked output and requires an explicit

Content-Length

header when the response body is not empty in order to support the HTTP 1.0 keep-alive. So when a HTTP 1.0 request is made and the lua_http10_buffering directive is turned

on

, ngx_lua will buffer the output of ngx.say and ngx.print calls and also postpone sending response headers until all the response body output is received. At that time ngx_lua can calculate the total length of the body and construct a proper

Content-Length

header to return to the HTTP 1.0 client. If the

Content-Length

response header is set in the running Lua code, however, this buffering will be disabled even if the lua_http10_buffering directive is turned

on

.

For large streaming output responses, it is important to disable the lua_http10_buffering directive to minimise memory usage.

Note that common HTTP benchmark tools such as

ab

and

http\_load

issue HTTP 1.0 requests by default. To force

curl

to send HTTP 1.0 requests, use the

-0

option.

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Statically Linking Pure Lua Modules

With LuaJIT 2.x, it is possible to statically link the bytecode of pure Lua modules into the Nginx executable.

You can use the

luajit

executable to compile

.lua

Lua module files to

.o

object files containing the exported bytecode data, and then link the

.o

files directly in your Nginx build.

Below is a trivial example to demonstrate this. Consider that we have the following

.lua

file named

foo.lua

:

-- foo.lua local \_M = {} function \_M.go() print("Hello from foo") end return \_M

And then we compile this

.lua

file to

foo.o

file:

/path/to/luajit/bin/luajit -bg foo.lua foo.o

What matters here is the name of the

.lua

file, which determines how you use this module later on the Lua land. The file name

foo.o

does not matter at all except the

.o

file extension (which tells

luajit

what output format is used). If you want to strip the Lua debug information from the resulting bytecode, you can just specify the

-b

option above instead of

-bg

.

Then when building Nginx or OpenResty, pass the

--with-ld-opt="foo.o"

option to the

./configure

script:

./configure --with-ld-opt="/path/to/foo.o" ...

Finally, you can just do the following in any Lua code run by ngx_lua:

local foo = require "foo" foo.go()

And this piece of code no longer depends on the external

foo.lua

file any more because it has already been compiled into the

nginx

executable.

If you want to use dot in the Lua module name when calling

require

, as in

local foo = require "resty.foo"

then you need to rename the

foo.lua

file to

resty\_foo.lua

before compiling it down to a

.o

file with the

luajit

command-line utility.

It is important to use exactly the same version of LuaJIT when compiling

.lua

files to

.o

files as building nginx + ngx_lua. This is because the LuaJIT bytecode format may be incompatible between different LuaJIT versions. When the bytecode format is incompatible, you will see a Lua runtime error saying that the Lua module is not found.

When you have multiple

.lua

files to compile and link, then just specify their

.o

files at the same time in the value of the

--with-ld-opt

option. For instance,

./configure --with-ld-opt="/path/to/foo.o /path/to/bar.o" ...

If you have too many

.o

files, then it might not be feasible to name them all in a single command. In this case, you can build a static library (or archive) for your

.o

files, as in

ar rcus libmyluafiles.a \*.o

then you can link the

myluafiles

archive as a whole to your nginx executable:

./configure \ --with-ld-opt="-L/path/to/lib -Wl,--whole-archive -lmyluafiles -Wl,--no-whole-archive"

where

/path/to/lib

is the path of the directory containing the

libmyluafiles.a

file. It should be noted that the linker option

--whole-archive

is required here because otherwise our archive will be skipped because no symbols in our archive are mentioned in the main parts of the nginx executable.

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Data Sharing within an Nginx Worker

To globally share data among all the requests handled by the same Nginx worker process, encapsulate the shared data into a Lua module, use the Lua

require

builtin to import the module, and then manipulate the shared data in Lua. This works because required Lua modules are loaded only once and all coroutines will share the same copy of the module (both its code and data).

Note that the use of global Lua variables is strongly discouraged, as it may lead to unexpected race conditions between concurrent requests.

Here is a small example on sharing data within an Nginx worker via a Lua module:

-- mydata.lua local \_M = {} local data = { dog = 3, cat = 4, pig = 5, } function \_M.get\_age(name) return data[name] end return \_M

and then accessing it from

nginx.conf

:

location /lua { content\_by\_lua\_block { local mydata = require "mydata" ngx.say(mydata.get\_age("dog")) } }

The

mydata

module in this example will only be loaded and run on the first request to the location

/lua

, and all subsequent requests to the same Nginx worker process will use the reloaded instance of the module as well as the same copy of the data in it, until a

HUP

signal is sent to the Nginx master process to force a reload. This data sharing technique is essential for high performance Lua applications based on this module.

Note that this data sharing is on a per-worker basis and not on a per-server basis. That is, when there are multiple Nginx worker processes under an Nginx master, data sharing cannot cross the process boundary between these workers.

It is usually recommended to share read-only data this way. You can also share changeable data among all the concurrent requests of each Nginx worker process as long as there is no nonblocking I/O operations (including ngx.sleep) in the middle of your calculations. As long as you do not give the control back to the Nginx event loop and ngx_lua's light thread scheduler (even implicitly), there can never be any race conditions in between. For this reason, always be very careful when you want to share changeable data on the worker level. Buggy optimizations can easily lead to hard-to-debug race conditions under load.

If server-wide data sharing is required, then use one or more of the following approaches:

  1. Use the ngx.shared.DICT API provided by this module.
  2. Use only a single Nginx worker and a single server (this is however not recommended when there is a multi core CPU or multiple CPUs in a single machine).
  3. Use data storage mechanisms such as
    memcached
    ,
    redis
    ,
    MySQL
    or
    PostgreSQL
    . The OpenResty official releases come with a set of companion Nginx modules and Lua libraries that provide interfaces with these data storage mechanisms.

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Known Issues

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TCP socket connect operation issues

The tcpsock:connect method may indicate

success

despite connection failures such as with

Connection Refused

errors.

However, later attempts to manipulate the cosocket object will fail and return the actual error status message generated by the failed connect operation.

This issue is due to limitations in the Nginx event model and only appears to affect Mac OS X.

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Lua Coroutine Yielding/Resuming

  • Because Lua's
    dofile
    and
    require
    builtins are currently implemented as C functions in LuaJIT 2.0/2.1, if the Lua file being loaded by
    dofile
    or
    require
    invokes ngx.location.capture*, ngx.exec, ngx.exit, or other API functions requiring yielding in the top-level scope of the Lua file, then the Lua error "attempt to yield across C-call boundary" will be raised. To avoid this, put these calls requiring yielding into your own Lua functions in the Lua file instead of the top-level scope of the file.

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Lua Variable Scope

Care must be taken when importing modules, and this form should be used:

local xxx = require('xxx')

instead of the old deprecated form:

require('xxx')

Here is the reason: by design, the global environment has exactly the same lifetime as the Nginx request handler associated with it. Each request handler has its own set of Lua global variables and that is the idea of request isolation. The Lua module is actually loaded by the first Nginx request handler and is cached by the

require()

built-in in the

package.loaded

table for later reference, and the

module()

builtin used by some Lua modules has the side effect of setting a global variable to the loaded module table. But this global variable will be cleared at the end of the request handler, and every subsequent request handler all has its own (clean) global environment. So one will get Lua exception for accessing the

nil

value.

The use of Lua global variables is a generally inadvisable in the ngx_lua context as:

  1. the misuse of Lua globals has detrimental side effects on concurrent requests when such variables should instead be local in scope,
  2. Lua global variables require Lua table look-ups in the global environment which is computationally expensive, and
  3. some Lua global variable references may include typing errors which make such difficult to debug.

It is therefore highly recommended to always declare such within an appropriate local scope instead.

-- Avoid foo = 123 -- Recommended local foo = 123 -- Avoid function foo() return 123 end -- Recommended local function foo() return 123 end

To find all instances of Lua global variables in your Lua code, run the lua-releng tool across all

.lua

source files:

$ lua-releng Checking use of Lua global variables in file lib/foo/bar.lua ... 1 [1489] SETGLOBAL 7 -1 ; contains 55 [1506] GETGLOBAL 7 -3 ; setvar 3 [1545] GETGLOBAL 3 -4 ; varexpand

The output says that the line 1489 of file

lib/foo/bar.lua

writes to a global variable named

contains

, the line 1506 reads from the global variable

setvar

, and line 1545 reads the global

varexpand

.

This tool will guarantee that local variables in the Lua module functions are all declared with the

local

keyword, otherwise a runtime exception will be thrown. It prevents undesirable race conditions while accessing such variables. See Data Sharing within an Nginx Worker for the reasons behind this.

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Locations Configured by Subrequest Directives of Other Modules

The ngx.location.capture and ngx.location.capture_multi directives cannot capture locations that include the add_before_body, add_after_body, auth_request, echo_location, echo_location_async, echo_subrequest, or echo_subrequest_async directives.

location /foo { content\_by\_lua\_block { res = ngx.location.capture("/bar") } } location /bar { echo\_location /blah; } location /blah { echo "Success!"; }
$ curl -i http://example.com/foo

will not work as expected.

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Cosockets Not Available Everywhere

Due to internal limitations in the Nginx core, the cosocket API is disabled in the following contexts: set_by_lua*, log_by_lua*, header_filter_by_lua*, and body_filter_by_lua.

The cosockets are currently also disabled in the init_by_lua* and init_worker_by_lua* directive contexts but we may add support for these contexts in the future because there is no limitation in the Nginx core (or the limitation might be worked around).

There exists a workaround, however, when the original context does not need to wait for the cosocket results. That is, creating a zero-delay timer via the ngx.timer.at API and do the cosocket results in the timer handler, which runs asynchronously as to the original context creating the timer.

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Special Escaping Sequences

NOTE Following the

v0.9.17

release, this pitfall can be avoided by using the

\*\_by\_lua\_block {}

configuration directives.

PCRE sequences such as

\d

,

\s

, or

\w

, require special attention because in string literals, the backslash character,

\

, is stripped out by both the Lua language parser and by the Nginx config file parser before processing if not within a

\*\_by\_lua\_block {}

directive. So the following snippet will not work as expected:

# nginx.conf ? location /test { ? content\_by\_lua ' ? local regex = "\d+" -- THIS IS WRONG OUTSIDE OF A \*\_by\_lua\_block DIRECTIVE ? local m = ngx.re.match("hello, 1234", regex) ? if m then ngx.say(m[0]) else ngx.say("not matched!") end ? '; ? } # evaluates to "not matched!"

To avoid this, double escape the backslash:

# nginx.conf location /test { content\_by\_lua ' local regex = "\\\\d+" local m = ngx.re.match("hello, 1234", regex) if m then ngx.say(m[0]) else ngx.say("not matched!") end '; } # evaluates to "1234"

Here,

\\\\d+

is stripped down to

\\d+

by the Nginx config file parser and this is further stripped down to

\d+

by the Lua language parser before running.

Alternatively, the regex pattern can be presented as a long-bracketed Lua string literal by encasing it in "long brackets",

[[...]]

, in which case backslashes have to only be escaped once for the Nginx config file parser.

# nginx.conf location /test { content\_by\_lua ' local regex = [[\\d+]] local m = ngx.re.match("hello, 1234", regex) if m then ngx.say(m[0]) else ngx.say("not matched!") end '; } # evaluates to "1234"

Here,

[[\\d+]]

is stripped down to

[[\d+]]

by the Nginx config file parser and this is processed correctly.

Note that a longer from of the long bracket,

[=[...]=]

, may be required if the regex pattern contains

[...]

sequences. The

[=[...]=]

form may be used as the default form if desired.

# nginx.conf location /test { content\_by\_lua ' local regex = [=[[0-9]+]=] local m = ngx.re.match("hello, 1234", regex) if m then ngx.say(m[0]) else ngx.say("not matched!") end '; } # evaluates to "1234"

An alternative approach to escaping PCRE sequences is to ensure that Lua code is placed in external script files and executed using the various

\*\_by\_lua\_file

directives. With this approach, the backslashes are only stripped by the Lua language parser and therefore only need to be escaped once each.

-- test.lua local regex = "\\d+" local m = ngx.re.match("hello, 1234", regex) if m then ngx.say(m[0]) else ngx.say("not matched!") end -- evaluates to "1234"

Within external script files, PCRE sequences presented as long-bracketed Lua string literals do not require modification.

-- test.lua local regex = [[\d+]] local m = ngx.re.match("hello, 1234", regex) if m then ngx.say(m[0]) else ngx.say("not matched!") end -- evaluates to "1234"

As noted earlier, PCRE sequences presented within

\*\_by\_lua\_block {}

directives (available following the

v0.9.17

release) do not require modification.

# nginx.conf location /test { content\_by\_lua\_block { local regex = [[\d+]] local m = ngx.re.match("hello, 1234", regex) if m then ngx.say(m[0]) else ngx.say("not matched!") end } } # evaluates to "1234"

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Mixing with SSI Not Supported

Mixing SSI with ngx_lua in the same Nginx request is not supported at all. Just use ngx_lua exclusively. Everything you can do with SSI can be done atop ngx_lua anyway and it can be more efficient when using ngx_lua.

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SPDY Mode Not Fully Supported

Certain Lua APIs provided by ngx_lua do not work in Nginx's SPDY mode yet: ngx.location.capture, ngx.location.capture_multi, and ngx.req.socket.

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Missing data on short circuited requests

Nginx may terminate a request early with (at least):

  • 400 (Bad Request)
  • 405 (Not Allowed)
  • 408 (Request Timeout)
  • 413 (Request Entity Too Large)
  • 414 (Request URI Too Large)
  • 494 (Request Headers Too Large)
  • 499 (Client Closed Request)
  • 500 (Internal Server Error)
  • 501 (Not Implemented)

This means that phases that normally run are skipped, such as the rewrite or access phase. This also means that later phases that are run regardless, e.g.log_by_lua, will not have access to information that is normally set in those phases.

Back to TOC

TODO

  • cosocket: implement LuaSocket's unconnected UDP API.
  • cosocket: add support in the context of init_by_lua*.
  • cosocket: implement the
    bind()
    method for stream-typed cosockets.
  • cosocket: review and merge aviramc's patch for adding the
    bsdrecv
    method.
  • cosocket: add configure options for different strategies of handling the cosocket connection exceeding in the pools.
  • review and apply vadim-pavlov's patch for ngx.location.capture's
    extra\_headers
    option
  • use
    ngx\_hash\_t
    to optimize the built-in header look-up process for ngx.req.set_header, ngx.header.HEADER, and etc.
  • add directives to run Lua codes when Nginx stops.
  • add
    ignore\_resp\_headers
    ,
    ignore\_resp\_body
    , and
    ignore\_resp
    options to ngx.location.capture and ngx.location.capture_multi methods, to allow micro performance tuning on the user side.
  • add automatic Lua code time slicing support by yielding and resuming the Lua VM actively via Lua's debug hooks.
  • add
    stat
    mode similar to mod_lua.
  • cosocket: add client SSL certificate support.

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Changes

The changes made in every release of this module are listed in the change logs of the OpenResty bundle:

https://openresty.org/#Changes

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Test Suite

The following dependencies are required to run the test suite:

  • Nginx version >= 1.4.2

Perl modules:

Nginx modules:

The order in which these modules are added during configuration is important because the position of any filter module in the filtering chain determines the final output, for example. The correct adding order is shown above.

Applications:

  • mysql: create database 'ngx_test', grant all privileges to user 'ngx_test', password is 'ngx_test'
  • memcached: listening on the default port, 11211.
  • redis: listening on the default port, 6379.

See also the developer build script for more details on setting up the testing environment.

To run the whole test suite in the default testing mode:

cd /path/to/lua-nginx-module export PATH=/path/to/your/nginx/sbin:$PATH prove -I/path/to/test-nginx/lib -r t

To run specific test files:

cd /path/to/lua-nginx-module export PATH=/path/to/your/nginx/sbin:$PATH prove -I/path/to/test-nginx/lib t/002-content.t t/003-errors.t

To run a specific test block in a particular test file, add the line

--- ONLY

to the test block you want to run, and then use the

prove

utility to run that

.t

file.

There are also various testing modes based on mockeagain, valgrind, and etc. Refer to the Test::Nginx documentation for more details for various advanced testing modes. See also the test reports for the Nginx test cluster running on Amazon EC2: https://qa.openresty.org.

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Copyright and License

This module is licensed under the BSD license.

Copyright (C) 2009-2017, by Xiaozhe Wang (chaoslawful) [email protected].

Copyright (C) 2009-2019, by Yichun "agentzh" Zhang (章亦春) [email protected], OpenResty Inc.

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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See Also

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Directives

The basic building blocks of scripting Nginx with Lua are directives. Directives are used to specify when the user Lua code is run and how the result will be used. Below is a diagram showing the order in which directives are executed.

Lua Nginx Modules Directives

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lua_load_resty_core

syntax: lualoadresty_core on|off

default: lualoadresty_core on

context: http

This directive is deprecated since the

v0.10.16

release of this module. The

resty.core

module fromlua-resty-core is now mandatorily loaded during the Lua VM initialization. Specifying this directive will have no effect.

This directive was first introduced in the

v0.10.15

release and used to optionally load the

resty.core

module.

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lua_capture_error_log

syntax: luacaptureerror_log size

default: none

context: http

Enables a buffer of the specified

size

for capturing all the Nginx error log message data (not just those produced by this module or the Nginx http subsystem, but everything) without touching files or disks.

You can use units like

k

and

m

in the

size

value, as in

lua\_capture\_error\_log 100k;

As a rule of thumb, a 4KB buffer can usually hold about 20 typical error log messages. So do the maths!

This buffer never grows. If it is full, new error log messages will replace the oldest ones in the buffer.

The size of the buffer must be bigger than the maximum length of a single error log message (which is 4K in OpenResty and 2K in stock NGINX).

You can read the messages in the buffer on the Lua land via theget_logs()function of thengx.errlogmodule of the lua-resty-corelibrary. This Lua API function will return the captured error log messages and also remove these already read from the global capturing buffer, making room for any new error log data. For this reason, the user should not configure this buffer to be too big if the user read the buffered error log data fast enough.

Note that the log level specified in the standard error_log directive_does_ have effect on this capturing facility. It only captures log messages of a level no lower than the specified log level in the error_log directive. The user can still choose to set an even higher filtering log level on the fly via the Lua API functionerrlog.set_filter_level. So it is more flexible than the static error_log directive.

It is worth noting that there is no way to capture the debugging logs without building OpenResty or Nginx with the

./configure

option

--with-debug

. And enabling debugging logs is strongly discouraged in production builds due to high overhead.

This directive was first introduced in the

v0.10.9

release.

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lua_use_default_type

syntax: luausedefault_type on | off

default: luausedefault_type on

context: http, server, location, location if

Specifies whether to use the MIME type specified by the default_type directive for the default value of the

Content-Type

response header. Deactivate this directive if a default

Content-Type

response header for Lua request handlers is not desired.

This directive is turned on by default.

This directive was first introduced in the

v0.9.1

release.

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lua_malloc_trim

syntax: luamalloctrim <request-count>

default: luamalloctrim 1000

context: http

Asks the underlying

libc

runtime library to release its cached free memory back to the operating system every

N

requests processed by the Nginx core. By default,

N

is 1000. You can configure the request count by using your own numbers. Smaller numbers mean more frequent releases, which may introduce higher CPU time consumption and smaller memory footprint while larger numbers usually lead to less CPU time overhead and relatively larger memory footprint. Just tune the number for your own use cases.

Configuring the argument to

0

essentially turns off the periodical memory trimming altogether.

lua\_malloc\_trim 0; # turn off trimming completely

The current implementation uses an Nginx log phase handler to do the request counting. So the appearance of thelog_subrequest on directives in

nginx.conf

may make the counting faster when subrequests are involved. By default, only "main requests" count.

Note that this directive does not affect the memory allocated by LuaJIT's own allocator based on the

mmap

system call.

This directive was first introduced in the

v0.10.7

release.

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lua_code_cache

syntax: luacodecache on | off

default: luacodecache on

context: http, server, location, location if

Enables or disables the Lua code cache for Lua code in

\*\_by\_lua\_file

directives (like set_by_lua_file andcontent_by_lua_file) and Lua modules.

When turning off, every request served by ngx_lua will run in a separate Lua VM instance, starting from the

0.9.3

release. So the Lua files referenced in set_by_lua_file,content_by_lua_file, access_by_lua_file, and etc will not be cached and all Lua modules used will be loaded from scratch. With this in place, developers can adopt an edit-and-refresh approach.

Please note however, that Lua code written inlined within nginx.conf such as those specified by set_by_lua, content_by_lua,access_by_lua, and rewrite_by_lua will not be updated when you edit the inlined Lua code in your

nginx.conf

file because only the Nginx config file parser can correctly parse the

nginx.conf

file and the only way is to reload the config file by sending a

HUP

signal or just to restart Nginx.

Even when the code cache is enabled, Lua files which are loaded by

dofile

or

loadfile

in *_by_lua_file cannot be cached (unless you cache the results yourself). Usually you can either use the init_by_luaor init_by_lua_file directives to load all such files or just make these Lua files true Lua modules and load them via

require

.

The ngx_lua module does not support the

stat

mode available with the Apache mod_ lua module (yet).

Disabling the Lua code cache is strongly discouraged for production use and should only be used during development as it has a significant negative impact on overall performance. For example, the performance of a "hello world" Lua example can drop by an order of magnitude after disabling the Lua code cache.

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lua_regex_cache_max_entries

syntax: luaregexcachemaxentries <num>

default: luaregexcachemaxentries 1024

context: http

Specifies the maximum number of entries allowed in the worker process level compiled regex cache.

The regular expressions used in ngx.re.match, ngx.re.gmatch, ngx.re.sub, and ngx.re.gsub will be cached within this cache if the regex option

o

(i.e., compile-once flag) is specified.

The default number of entries allowed is 1024 and when this limit is reached, new regular expressions will not be cached (as if the

o

option was not specified) and there will be one, and only one, warning in the

error.log

file:

2011/08/27 23:18:26 [warn] 31997#0: \*1 lua exceeding regex cache max entries (1024), ...

If you are using the

ngx.re.\*

implementation of lua-resty-core by loading the

resty.core.regex

module (or just the

resty.core

module), then an LRU cache is used for the regex cache being used here.

Do not activate the

o

option for regular expressions (and/or

replace

string arguments for ngx.re.sub and ngx.re.gsub) that are generated on the fly and give rise to infinite variations to avoid hitting the specified limit.

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lua_regex_match_limit

syntax: luaregexmatch_limit <num>

default: luaregexmatch_limit 0

context: http

Specifies the "match limit" used by the PCRE library when executing the ngx.re API. To quote the PCRE manpage, "the limit ... has the effect of limiting the amount of backtracking that can take place."

When the limit is hit, the error string "pcre_exec() failed: -8" will be returned by the ngx.re API functions on the Lua land.

When setting the limit to 0, the default "match limit" when compiling the PCRE library is used. And this is the default value of this directive.

This directive was first introduced in the

v0.8.5

release.

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lua_package_path

syntax: luapackagepath <lua-style-path-str>

default: The content of LUA_PATH environment variable or Lua's compiled-in defaults.

context: http

Sets the Lua module search path used by scripts specified by set_by_lua,content_by_lua and others. The path string is in standard Lua path form, and

;;

can be used to stand for the original search paths.

As from the

v0.5.0rc29

release, the special notation

$prefix

or

${prefix}

can be used in the search path string to indicate the path of the

server prefix

usually determined by the

-p PATH

command-line option while starting the Nginx server.

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lua_package_cpath

syntax: luapackagecpath <lua-style-cpath-str>

default: The content of LUA_CPATH environment variable or Lua's compiled-in defaults.

context: http

Sets the Lua C-module search path used by scripts specified by set_by_lua,content_by_lua and others. The cpath string is in standard Lua cpath form, and

;;

can be used to stand for the original cpath.

As from the

v0.5.0rc29

release, the special notation

$prefix

or

${prefix}

can be used in the search path string to indicate the path of the

server prefix

usually determined by the

-p PATH

command-line option while starting the Nginx server.

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init_by_lua

syntax: initbylua <lua-script-str>

context: http

phase: loading-config

NOTE Use of this directive is discouraged following the

v0.9.17

release. Use the init_by_lua_block directive instead.

Runs the Lua code specified by the argument

<lua-script-str></lua-script-str>

on the global Lua VM level when the Nginx master process (if any) is loading the Nginx config file.

When Nginx receives the

HUP

signal and starts reloading the config file, the Lua VM will also be re-created and

init\_by\_lua

will run again on the new Lua VM. In case that the lua_code_cache directive is turned off (default on), the

init\_by\_lua

handler will run upon every request because in this special mode a standalone Lua VM is always created for each request.

Usually you can pre-load Lua modules at server start-up by means of this hook and take advantage of modern operating systems' copy-on-write (COW) optimization. Here is an example for pre-loading Lua modules:

# this runs before forking out nginx worker processes: init\_by\_lua\_block { require "cjson" } server { location = /api { content\_by\_lua\_block { -- the following require() will just return -- the already loaded module from package.loaded: ngx.say(require "cjson".encode{dog = 5, cat = 6}) } } }

You can also initialize the lua_shared_dict shm storage at this phase. Here is an example for this:

lua\_shared\_dict dogs 1m; init\_by\_lua\_block { local dogs = ngx.shared.dogs; dogs:set("Tom", 56) } server { location = /api { content\_by\_lua\_block { local dogs = ngx.shared.dogs; ngx.say(dogs:get("Tom")) } } }

But note that, the lua_shared_dict's shm storage will not be cleared through a config reload (via the

HUP

signal, for example). So if you do not want to re-initialize the shm storage in your

init\_by\_lua

code in this case, then you just need to set a custom flag in the shm storage and always check the flag in your

init\_by\_lua

code.

Because the Lua code in this context runs before Nginx forks its worker processes (if any), data or code loaded here will enjoy the Copy-on-write (COW) feature provided by many operating systems among all the worker processes, thus saving a lot of memory.

Do not initialize your own Lua global variables in this context because use of Lua global variables have performance penalties and can lead to global namespace pollution (see the Lua Variable Scope section for more details). The recommended way is to use proper Lua module files (but do not use the standard Lua function module() to define Lua modules because it pollutes the global namespace as well) and call require() to load your own module files in

init\_by\_lua

or other contexts (require() does cache the loaded Lua modules in the global

package.loaded

table in the Lua registry so your modules will only loaded once for the whole Lua VM instance).

Only a small set of the Nginx API for Lua is supported in this context:

More Nginx APIs for Lua may be supported in this context upon future user requests.

Basically you can safely use Lua libraries that do blocking I/O in this very context because blocking the master process during server start-up is completely okay. Even the Nginx core does blocking I/O (at least on resolving upstream's host names) at the configure-loading phase.

You should be very careful about potential security vulnerabilities in your Lua code registered in this context because the Nginx master process is often run under the

root

account.

This directive was first introduced in the

v0.5.5

release.

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init_by_lua_block

syntax: initbylua_block { lua-script }

context: http

phase: loading-config

Similar to the init_by_lua directive except that this directive inlines the Lua source directly inside a pair of curly braces (

{}

) instead of in an Nginx string literal (which requires special character escaping).

For instance,

init\_by\_lua\_block { print("I need no extra escaping here, for example: \r\nblah") }

This directive was first introduced in the

v0.9.17

release.

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init_by_lua_file

syntax: initbylua_file <path-to-lua-script-file>

context: http

phase: loading-config

Equivalent to init_by_lua, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code or LuaJIT bytecode to be executed.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

This directive was first introduced in the

v0.5.5

release.

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init_worker_by_lua

syntax: initworkerby_lua <lua-script-str>

context: http

phase: starting-worker

NOTE Use of this directive is discouraged following the

v0.9.17

release. Use the init_worker_by_lua_block directive instead.

Runs the specified Lua code upon every Nginx worker process's startup when the master process is enabled. When the master process is disabled, this hook will just run after init_by_lua*.

This hook is often used to create per-worker reoccurring timers (via the ngx.timer.at Lua API), either for backend health-check or other timed routine work. Below is an example,

init\_worker\_by\_lua ' local delay = 3 -- in seconds local new\_timer = ngx.timer.at local log = ngx.log local ERR = ngx.ERR local check check = function(premature) if not premature then -- do the health check or other routine work local ok, err = new\_timer(delay, check) if not ok then log(ERR, "failed to create timer: ", err) return end end -- do something in timer end local hdl, err = new\_timer(delay, check) if not hdl then log(ERR, "failed to create timer: ", err) return end -- other job in init\_worker\_by\_lua ';

This directive was first introduced in the

v0.9.5

release.

This hook no longer runs in the cache manager and cache loader processes since the

v0.10.12

release.

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init_worker_by_lua_block

syntax: initworkerbyluablock { lua-script }

context: http

phase: starting-worker

Similar to the init_worker_by_lua directive except that this directive inlines the Lua source directly inside a pair of curly braces (

{}

) instead of in an Nginx string literal (which requires special character escaping).

For instance,

init\_worker\_by\_lua\_block { print("I need no extra escaping here, for example: \r\nblah") }

This directive was first introduced in the

v0.9.17

release.

This hook no longer runs in the cache manager and cache loader processes since the

v0.10.12

release.

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init_worker_by_lua_file

syntax: initworkerbyluafile <lua-file-path>

context: http

phase: starting-worker

Similar to init_worker_by_lua, but accepts the file path to a Lua source file or Lua bytecode file.

This directive was first introduced in the

v0.9.5

release.

This hook no longer runs in the cache manager and cache loader processes since the

v0.10.12

release.

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set_by_lua

syntax: setbylua $res <lua-script-str> [$arg1 $arg2 ...]

context: server, server if, location, location if

phase: rewrite

NOTE Use of this directive is discouraged following the

v0.9.17

release. Use the set_by_lua_block directive instead.

Executes code specified in

<lua-script-str></lua-script-str>

with optional input arguments

$arg1 $arg2 ...

, and returns string output to

$res

. The code in

<lua-script-str></lua-script-str>

can make API calls and can retrieve input arguments from the

ngx.arg

table (index starts from

1

and increases sequentially).

This directive is designed to execute short, fast running code blocks as the Nginx event loop is blocked during code execution. Time consuming code sequences should therefore be avoided.

This directive is implemented by injecting custom commands into the standard ngx_http_rewrite_module's command list. Because ngx_http_rewrite_module does not support nonblocking I/O in its commands, Lua APIs requiring yielding the current Lua "light thread" cannot work in this directive.

At least the following API functions are currently disabled within the context of

set\_by\_lua

:

In addition, note that this directive can only write out a value to a single Nginx variable at a time. However, a workaround is possible using the ngx.var.VARIABLE interface.

location /foo { set $diff ''; # we have to predefine the $diff variable here set\_by\_lua $sum ' local a = 32 local b = 56 ngx.var.diff = a - b; -- write to $diff directly return a + b; -- return the $sum value normally '; echo "sum = $sum, diff = $diff"; }

This directive can be freely mixed with all directives of the ngx_http_rewrite_module, set-misc-nginx-module, and array-var-nginx-module modules. All of these directives will run in the same order as they appear in the config file.

set $foo 32; set\_by\_lua $bar 'return tonumber(ngx.var.foo) + 1'; set $baz "bar: $bar"; # $baz == "bar: 33"

As from the

v0.5.0rc29

release, Nginx variable interpolation is disabled in the

<lua-script-str></lua-script-str>

argument of this directive and therefore, the dollar sign character (

$

) can be used directly.

This directive requires the ngx_devel_kit module.

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set_by_lua_block

syntax: setbylua_block $res { lua-script }

context: server, server if, location, location if

phase: rewrite

Similar to the set_by_lua directive except that

  1. this directive inlines the Lua source directly inside a pair of curly braces (
    {}
    ) instead of in an Nginx string literal (which requires special character escaping), and
  2. this directive does not support extra arguments after the Lua script as in set_by_lua.

For example,

set\_by\_lua\_block $res { return 32 + math.cos(32) } # $res now has the value "32.834223360507" or alike.

No special escaping is required in the Lua code block.

This directive was first introduced in the

v0.9.17

release.

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set_by_lua_file

syntax: setbylua_file $res <path-to-lua-script-file> [$arg1 $arg2 ...]

context: server, server if, location, location if

phase: rewrite

Equivalent to set_by_lua, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or, as from the

v0.5.0rc32

release, the LuaJIT bytecode to be executed.

Nginx variable interpolation is supported in the

<path-to-lua-script-file></path-to-lua-script-file>

argument string of this directive. But special care must be taken for injection attacks.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

When the Lua code cache is turned on (by default), the user code is loaded once at the first request and cached and the Nginx config must be reloaded each time the Lua source file is modified. The Lua code cache can be temporarily disabled during development by switching lua_code_cache

off

in

nginx.conf

to avoid reloading Nginx.

This directive requires the ngx_devel_kit module.

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content_by_lua

syntax: contentbylua <lua-script-str>

context: location, location if

phase: content

NOTE Use of this directive is discouraged following the

v0.9.17

release. Use the content_by_lua_block directive instead.

Acts as a "content handler" and executes Lua code string specified in

<lua-script-str></lua-script-str>

for every request. The Lua code may make API calls and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox).

Do not use this directive and other content handler directives in the same location. For example, this directive and the proxy_pass directive should not be used in the same location.

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content_by_lua_block

syntax: contentbylua_block { lua-script }

context: location, location if

phase: content

Similar to the content_by_lua directive except that this directive inlines the Lua source directly inside a pair of curly braces (

{}

) instead of in an Nginx string literal (which requires special character escaping).

For instance,

content\_by\_lua\_block { ngx.say("I need no extra escaping here, for example: \r\nblah") }

This directive was first introduced in the

v0.9.17

release.

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content_by_lua_file

syntax: contentbylua_file <path-to-lua-script-file>

context: location, location if

phase: content

Equivalent to content_by_lua, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or, as from the

v0.5.0rc32

release, the LuaJIT bytecode to be executed.

Nginx variables can be used in the

<path-to-lua-script-file></path-to-lua-script-file>

string to provide flexibility. This however carries some risks and is not ordinarily recommended.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

When the Lua code cache is turned on (by default), the user code is loaded once at the first request and cached and the Nginx config must be reloaded each time the Lua source file is modified. The Lua code cache can be temporarily disabled during development by switching lua_code_cache

off

in

nginx.conf

to avoid reloading Nginx.

Nginx variables are supported in the file path for dynamic dispatch, for example:

# CAUTION: contents in nginx var must be carefully filtered, # otherwise there'll be great security risk! location ~ ^/app/([-\_a-zA-Z0-9/]+) { set $path $1; content\_by\_lua\_file /path/to/lua/app/root/$path.lua; }

But be very careful about malicious user inputs and always carefully validate or filter out the user-supplied path components.

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rewrite_by_lua

syntax: rewritebylua <lua-script-str>

context: http, server, location, location if

phase: rewrite tail

NOTE Use of this directive is discouraged following the

v0.9.17

release. Use the rewrite_by_lua_block directive instead.

Acts as a rewrite phase handler and executes Lua code string specified in

<lua-script-str></lua-script-str>

for every request. The Lua code may make API calls and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox).

Note that this handler always runs after the standard ngx_http_rewrite_module. So the following will work as expected:

location /foo { set $a 12; # create and initialize $a set $b ""; # create and initialize $b rewrite\_by\_lua 'ngx.var.b = tonumber(ngx.var.a) + 1'; echo "res = $b"; }

because

set $a 12

and

set $b ""

run before rewrite_by_lua.

On the other hand, the following will not work as expected:

? location /foo { ? set $a 12; # create and initialize $a ? set $b ''; # create and initialize $b ? rewrite\_by\_lua 'ngx.var.b = tonumber(ngx.var.a) + 1'; ? if ($b = '13') { ? rewrite ^ /bar redirect; ? break; ? } ? ? echo "res = $b"; ? }

because

if

runs before rewrite_by_lua even if it is placed after rewrite_by_lua in the config.

The right way of doing this is as follows:

location /foo { set $a 12; # create and initialize $a set $b ''; # create and initialize $b rewrite\_by\_lua ' ngx.var.b = tonumber(ngx.var.a) + 1 if tonumber(ngx.var.b) == 13 then return ngx.redirect("/bar"); end '; echo "res = $b"; }

Note that the ngx_eval module can be approximated by using rewrite_by_lua. For example,

location / { eval $res { proxy\_pass http://foo.com/check-spam; } if ($res = 'spam') { rewrite ^ /terms-of-use.html redirect; } fastcgi\_pass ...; }

can be implemented in ngx_lua as:

location = /check-spam { internal; proxy\_pass http://foo.com/check-spam; } location / { rewrite\_by\_lua ' local res = ngx.location.capture("/check-spam") if res.body == "spam" then return ngx.redirect("/terms-of-use.html") end '; fastcgi\_pass ...; }

Just as any other rewrite phase handlers, rewrite_by_lua also runs in subrequests.

Note that when calling

ngx.exit(ngx.OK)

within a rewrite_by_lua handler, the Nginx request processing control flow will still continue to the content handler. To terminate the current request from within a rewrite_by_lua handler, call ngx.exit with status >= 200 (

ngx.HTTP\_OK

) and status < 300 (

ngx.HTTP\_SPECIAL\_RESPONSE

) for successful quits and

ngx.exit(ngx.HTTP\_INTERNAL\_SERVER\_ERROR)

(or its friends) for failures.

If the ngx_http_rewrite_module's rewrite directive is used to change the URI and initiate location re-lookups (internal redirections), then any rewrite_by_lua or rewrite_by_lua_file code sequences within the current location will not be executed. For example,

location /foo { rewrite ^ /bar; rewrite\_by\_lua 'ngx.exit(503)'; } location /bar { ... }

Here the Lua code

ngx.exit(503)

will never run. This will be the case if

rewrite ^ /bar last

is used as this will similarly initiate an internal redirection. If the

break

modifier is used instead, there will be no internal redirection and the

rewrite\_by\_lua

code will be executed.

The

rewrite\_by\_lua

code will always run at the end of the

rewrite

request-processing phase unless rewrite_by_lua_no_postpone is turned on.

Back to TOC

rewrite_by_lua_block

syntax: rewritebylua_block { lua-script }

context: http, server, location, location if

phase: rewrite tail

Similar to the rewrite_by_lua directive except that this directive inlines the Lua source directly inside a pair of curly braces (

{}

) instead of in an Nginx string literal (which requires special character escaping).

For instance,

rewrite\_by\_lua\_block { do\_something("hello, world!\nhiya\n") }

This directive was first introduced in the

v0.9.17

release.

Back to TOC

rewrite_by_lua_file

syntax: rewritebylua_file <path-to-lua-script-file>

context: http, server, location, location if

phase: rewrite tail

Equivalent to rewrite_by_lua, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or, as from the

v0.5.0rc32

release, the LuaJIT bytecode to be executed.

Nginx variables can be used in the

<path-to-lua-script-file></path-to-lua-script-file>

string to provide flexibility. This however carries some risks and is not ordinarily recommended.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

When the Lua code cache is turned on (by default), the user code is loaded once at the first request and cached and the Nginx config must be reloaded each time the Lua source file is modified. The Lua code cache can be temporarily disabled during development by switching lua_code_cache

off

in

nginx.conf

to avoid reloading Nginx.

The

rewrite\_by\_lua\_file

code will always run at the end of the

rewrite

request-processing phase unless rewrite_by_lua_no_postpone is turned on.

Nginx variables are supported in the file path for dynamic dispatch just as in content_by_lua_file.

Back to TOC

access_by_lua

syntax: accessbylua <lua-script-str>

context: http, server, location, location if

phase: access tail

NOTE Use of this directive is discouraged following the

v0.9.17

release. Use the access_by_lua_block directive instead.

Acts as an access phase handler and executes Lua code string specified in

<lua-script-str></lua-script-str>

for every request. The Lua code may make API calls and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox).

Note that this handler always runs after the standard ngx_http_access_module. So the following will work as expected:

location / { deny 192.168.1.1; allow 192.168.1.0/24; allow 10.1.1.0/16; deny all; access\_by\_lua ' local res = ngx.location.capture("/mysql", { ... }) ... '; # proxy\_pass/fastcgi\_pass/... }

That is, if a client IP address is in the blacklist, it will be denied before the MySQL query for more complex authentication is executed by access_by_lua.

Note that the ngx_auth_request module can be approximated by using access_by_lua:

location / { auth\_request /auth; # proxy\_pass/fastcgi\_pass/postgres\_pass/... }

can be implemented in ngx_lua as:

location / { access\_by\_lua ' local res = ngx.location.capture("/auth") if res.status == ngx.HTTP\_OK then return end if res.status == ngx.HTTP\_FORBIDDEN then ngx.exit(res.status) end ngx.exit(ngx.HTTP\_INTERNAL\_SERVER\_ERROR) '; # proxy\_pass/fastcgi\_pass/postgres\_pass/... }

As with other access phase handlers, access_by_lua will not run in subrequests.

Note that when calling

ngx.exit(ngx.OK)

within a access_by_lua handler, the Nginx request processing control flow will still continue to the content handler. To terminate the current request from within a access_by_lua handler, call ngx.exit with status >= 200 (

ngx.HTTP\_OK

) and status < 300 (

ngx.HTTP\_SPECIAL\_RESPONSE

) for successful quits and

ngx.exit(ngx.HTTP\_INTERNAL\_SERVER\_ERROR)

(or its friends) for failures.

Starting from the

v0.9.20

release, you can use the access_by_lua_no_postponedirective to control when to run this handler inside the "access" request-processing phase of Nginx.

Back to TOC

access_by_lua_block

syntax: accessbylua_block { lua-script }

context: http, server, location, location if

phase: access tail

Similar to the access_by_lua directive except that this directive inlines the Lua source directly inside a pair of curly braces (

{}

) instead of in an Nginx string literal (which requires special character escaping).

For instance,

access\_by\_lua\_block { do\_something("hello, world!\nhiya\n") }

This directive was first introduced in the

v0.9.17

release.

Back to TOC

access_by_lua_file

syntax: accessbylua_file <path-to-lua-script-file>

context: http, server, location, location if

phase: access tail

Equivalent to access_by_lua, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or, as from the

v0.5.0rc32

release, the LuaJIT bytecode to be executed.

Nginx variables can be used in the

<path-to-lua-script-file></path-to-lua-script-file>

string to provide flexibility. This however carries some risks and is not ordinarily recommended.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

When the Lua code cache is turned on (by default), the user code is loaded once at the first request and cached and the Nginx config must be reloaded each time the Lua source file is modified. The Lua code cache can be temporarily disabled during development by switching lua_code_cache

off

in

nginx.conf

to avoid repeatedly reloading Nginx.

Nginx variables are supported in the file path for dynamic dispatch just as in content_by_lua_file.

Back to TOC

header_filter_by_lua

syntax: headerfilterby_lua <lua-script-str>

context: http, server, location, location if

phase: output-header-filter

NOTE Use of this directive is discouraged following the

v0.9.17

release. Use the header_filter_by_lua_block directive instead.

Uses Lua code specified in

<lua-script-str></lua-script-str>

to define an output header filter.

Note that the following API functions are currently disabled within this context:

Here is an example of overriding a response header (or adding one if absent) in our Lua header filter:

location / { proxy\_pass http://mybackend; header\_filter\_by\_lua 'ngx.header.Foo = "blah"'; }

This directive was first introduced in the

v0.2.1rc20

release.

Back to TOC

header_filter_by_lua_block

syntax: headerfilterbyluablock { lua-script }

context: http, server, location, location if

phase: output-header-filter

Similar to the header_filter_by_lua directive except that this directive inlines the Lua source directly inside a pair of curly braces (

{}

) instead of in an Nginx string literal (which requires special character escaping).

For instance,

header\_filter\_by\_lua\_block { ngx.header["content-length"] = nil }

This directive was first introduced in the

v0.9.17

release.

Back to TOC

header_filter_by_lua_file

syntax: headerfilterbyluafile <path-to-lua-script-file>

context: http, server, location, location if

phase: output-header-filter

Equivalent to header_filter_by_lua, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or as from the

v0.5.0rc32

release, the LuaJIT bytecode to be executed.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

This directive was first introduced in the

v0.2.1rc20

release.

Back to TOC

body_filter_by_lua

syntax: bodyfilterby_lua <lua-script-str>

context: http, server, location, location if

phase: output-body-filter

NOTE Use of this directive is discouraged following the

v0.9.17

release. Use the body_filter_by_lua_block directive instead.

Uses Lua code specified in

<lua-script-str></lua-script-str>

to define an output body filter.

The input data chunk is passed via ngx.arg[1] (as a Lua string value) and the "eof" flag indicating the end of the response body data stream is passed via ngx.arg[2] (as a Lua boolean value).

Behind the scene, the "eof" flag is just the

last\_buf

(for main requests) or

last\_in\_chain

(for subrequests) flag of the Nginx chain link buffers. (Before the

v0.7.14

release, the "eof" flag does not work at all in subrequests.)

The output data stream can be aborted immediately by running the following Lua statement:

return ngx.ERROR

This will truncate the response body and usually result in incomplete and also invalid responses.

The Lua code can pass its own modified version of the input data chunk to the downstream Nginx output body filters by overriding ngx.arg[1] with a Lua string or a Lua table of strings. For example, to transform all the lowercase letters in the response body, we can just write:

location / { proxy\_pass http://mybackend; body\_filter\_by\_lua 'ngx.arg[1] = string.upper(ngx.arg[1])'; }

When setting

nil

or an empty Lua string value to

ngx.arg[1]

, no data chunk will be passed to the downstream Nginx output filters at all.

Likewise, new "eof" flag can also be specified by setting a boolean value to ngx.arg[2]. For example,

location /t { echo hello world; echo hiya globe; body\_filter\_by\_lua ' local chunk = ngx.arg[1] if string.match(chunk, "hello") then ngx.arg[2] = true -- new eof return end -- just throw away any remaining chunk data ngx.arg[1] = nil '; }

Then

GET /t

will just return the output

hello world

That is, when the body filter sees a chunk containing the word "hello", then it will set the "eof" flag to true immediately, resulting in truncated but still valid responses.

When the Lua code may change the length of the response body, then it is required to always clear out the

Content-Length

response header (if any) in a header filter to enforce streaming output, as in

location /foo { # fastcgi\_pass/proxy\_pass/... header\_filter\_by\_lua\_block { ngx.header.content\_length = nil } body\_filter\_by\_lua 'ngx.arg[1] = string.len(ngx.arg[1]) .. "\\n"'; }

Note that the following API functions are currently disabled within this context due to the limitations in Nginx output filter's current implementation:

Nginx output filters may be called multiple times for a single request because response body may be delivered in chunks. Thus, the Lua code specified by in this directive may also run multiple times in the lifetime of a single HTTP request.

This directive was first introduced in the

v0.5.0rc32

release.

Back to TOC

body_filter_by_lua_block

syntax: bodyfilterbyluablock { lua-script-str }

context: http, server, location, location if

phase: output-body-filter

Similar to the body_filter_by_lua directive except that this directive inlines the Lua source directly inside a pair of curly braces (

{}

) instead of in an Nginx string literal (which requires special character escaping).

For instance,

body\_filter\_by\_lua\_block { local data, eof = ngx.arg[1], ngx.arg[2] }

This directive was first introduced in the

v0.9.17

release.

Back to TOC

body_filter_by_lua_file

syntax: bodyfilterbyluafile <path-to-lua-script-file>

context: http, server, location, location if

phase: output-body-filter

Equivalent to body_filter_by_lua, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or, as from the

v0.5.0rc32

release, the LuaJIT bytecode to be executed.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

This directive was first introduced in the

v0.5.0rc32

release.

Back to TOC

log_by_lua

syntax: logbylua <lua-script-str>

context: http, server, location, location if

phase: log

NOTE Use of this directive is discouraged following the

v0.9.17

release. Use the log_by_lua_block directive instead.

Runs the Lua source code inlined as the

<lua-script-str></lua-script-str>

at the

log

request processing phase. This does not replace the current access logs, but runs before.

Note that the following API functions are currently disabled within this context:

Here is an example of gathering average data for $upstream_response_time:

lua\_shared\_dict log\_dict 5M; server { location / { proxy\_pass http://mybackend; log\_by\_lua ' local log\_dict = ngx.shared.log\_dict local upstream\_time = tonumber(ngx.var.upstream\_response\_time) local sum = log\_dict:get("upstream\_time-sum") or 0 sum = sum + upstream\_time log\_dict:set("upstream\_time-sum", sum) local newval, err = log\_dict:incr("upstream\_time-nb", 1) if not newval and err == "not found" then log\_dict:add("upstream\_time-nb", 0) log\_dict:incr("upstream\_time-nb", 1) end '; } location = /status { content\_by\_lua\_block { local log\_dict = ngx.shared.log\_dict local sum = log\_dict:get("upstream\_time-sum") local nb = log\_dict:get("upstream\_time-nb") if nb and sum then ngx.say("average upstream response time: ", sum / nb, " (", nb, " reqs)") else ngx.say("no data yet") end } } }

This directive was first introduced in the

v0.5.0rc31

release.

Back to TOC

log_by_lua_block

syntax: logbylua_block { lua-script }

context: http, server, location, location if

phase: log

Similar to the log_by_lua directive except that this directive inlines the Lua source directly inside a pair of curly braces (

{}

) instead of in an Nginx string literal (which requires special character escaping).

For instance,

log\_by\_lua\_block { print("I need no extra escaping here, for example: \r\nblah") }

This directive was first introduced in the

v0.9.17

release.

Back to TOC

log_by_lua_file

syntax: logbylua_file <path-to-lua-script-file>

context: http, server, location, location if

phase: log

Equivalent to log_by_lua, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or, as from the

v0.5.0rc32

release, the LuaJIT bytecode to be executed.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

This directive was first introduced in the

v0.5.0rc31

release.

Back to TOC

balancer_by_lua_block

syntax: balancerbylua_block { lua-script }

context: upstream

phase: content

This directive runs Lua code as an upstream balancer for any upstream entities defined by the

upstream {}

configuration block.

For instance,

upstream foo { server 127.0.0.1; balancer\_by\_lua\_block { -- use Lua to do something interesting here -- as a dynamic balancer } } server { location / { proxy\_pass http://foo; } }

The resulting Lua load balancer can work with any existing Nginx upstream modules like ngx_proxy andngx_fastcgi.

Also, the Lua load balancer can work with the standard upstream connection pool mechanism, i.e., the standard keepalive directive. Just ensure that the keepalive directive is used after this

balancer\_by\_lua\_block

directive in a single

upstream {}

configuration block.

The Lua load balancer can totally ignore the list of servers defined in the

upstream {}

block and select peer from a completely dynamic server list (even changing per request) via thengx.balancer module from the lua-resty-core library.

The Lua code handler registered by this directive might get called more than once in a single downstream request when the Nginx upstream mechanism retries the request on conditions specified by directives like the proxy_next_upstreamdirective.

This Lua code execution context does not support yielding, so Lua APIs that may yield (like cosockets and "light threads") are disabled in this context. One can usually work around this limitation by doing such operations in an earlier phase handler (likeaccess_by_lua*) and passing along the result into this context via the ngx.ctx table.

This directive was first introduced in the

v0.10.0

release.

Back to TOC

balancer_by_lua_file

syntax: balancerbylua_file <path-to-lua-script-file>

context: upstream

phase: content

Equivalent to balancer_by_lua_block, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or, as from the

v0.5.0rc32

release, the LuaJIT bytecode to be executed.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

This directive was first introduced in the

v0.10.0

release.

Back to TOC

lua_need_request_body

syntax: luaneedrequest_body <on|off>

default: off

context: http, server, location, location if

phase: depends on usage

Determines whether to force the request body data to be read before running rewrite/access/access_by_lua* or not. The Nginx core does not read the client request body by default and if request body data is required, then this directive should be turned

on

or the ngx.req.read_body function should be called within the Lua code.

To read the request body data within the $request_body variable,client_body_buffer_size must have the same value as client_max_body_size. Because when the content length exceeds client_body_buffer_size but less than client_max_body_size, Nginx will buffer the data into a temporary file on the disk, which will lead to empty value in the $request_body variable.

If the current location includes rewrite_by_lua* directives, then the request body will be read just before the rewrite_by_lua* code is run (and also at the

rewrite

phase). Similarly, if only content_by_lua is specified, the request body will not be read until the content handler's Lua code is about to run (i.e., the request body will be read during the content phase).

It is recommended however, to use the ngx.req.read_body and ngx.req.discard_body functions for finer control over the request body reading process instead.

This also applies to access_by_lua*.

Back to TOC

ssl_certificate_by_lua_block

syntax: sslcertificatebyluablock { lua-script }

context: server

phase: right-before-SSL-handshake

This directive runs user Lua code when Nginx is about to start the SSL handshake for the downstream SSL (https) connections.

It is particularly useful for setting the SSL certificate chain and the corresponding private key on a per-request basis. It is also useful to load such handshake configurations nonblockingly from the remote (for example, with the cosocket API). And one can also do per-request OCSP stapling handling in pure Lua here as well.

Another typical use case is to do SSL handshake traffic control nonblockingly in this context, with the help of the lua-resty-limit-traffic#readmelibrary, for example.

One can also do interesting things with the SSL handshake requests from the client side, like rejecting old SSL clients using the SSLv3 protocol or even below selectively.

The ngx.ssland ngx.ocsp Lua modules provided by the lua-resty-corelibrary are particularly useful in this context. You can use the Lua API offered by these two Lua modules to manipulate the SSL certificate chain and private key for the current SSL connection being initiated.

This Lua handler does not run at all, however, when Nginx/OpenSSL successfully resumes the SSL session via SSL session IDs or TLS session tickets for the current SSL connection. In other words, this Lua handler only runs when Nginx has to initiate a full SSL handshake.

Below is a trivial example using thengx.ssl module at the same time:

server { listen 443 ssl; server\_name test.com; ssl\_certificate\_by\_lua\_block { print("About to initiate a new SSL handshake!") } location / { root html; } }

See more complicated examples in the ngx.ssland ngx.ocspLua modules' official documentation.

Uncaught Lua exceptions in the user Lua code immediately abort the current SSL session, so does thengx.exit call with an error code like

ngx.ERROR

.

This Lua code execution context does support yielding, so Lua APIs that may yield (like cosockets, sleeping, and "light threads") are enabled in this context.

Note, however, you still need to configure the ssl_certificate andssl_certificate_keydirectives even though you will not use this static certificate and private key at all. This is because the NGINX core requires their appearance otherwise you are seeing the following error while starting NGINX:

nginx: [emerg] no ssl configured for the server

This directive requires OpenSSL 1.0.2e or greater.

If you are using the official pre-built packages forOpenResty 1.9.7.2 or later, then everything should work out of the box.

If you are not using one of the OpenSSL packages provided byOpenResty, you will need to apply patches to OpenSSL in order to use this directive:

https://openresty.org/en/openssl-patches.html

Similarly, if you are not using the Nginx core shipped withOpenResty 1.9.7.2 or later, you will need to apply patches to the standard Nginx core:

https://openresty.org/en/nginx-ssl-patches.html

This directive was first introduced in the

v0.10.0

release.

Back to TOC

ssl_certificate_by_lua_file

syntax: sslcertificatebyluafile <path-to-lua-script-file>

context: server

phase: right-before-SSL-handshake

Equivalent to ssl_certificate_by_lua_block, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or, as from the

v0.5.0rc32

release, the LuaJIT bytecode to be executed.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

This directive was first introduced in the

v0.10.0

release.

Back to TOC

ssl_session_fetch_by_lua_block

syntax: sslsessionfetchbylua_block { lua-script }

context: http

phase: right-before-SSL-handshake

This directive runs Lua code to look up and load the SSL session (if any) according to the session ID provided by the current SSL handshake request for the downstream.

The Lua API for obtaining the current session ID and loading a cached SSL session data is provided in the ngx.ssl.sessionLua module shipped with the lua-resty-corelibrary.

Lua APIs that may yield, like ngx.sleep and cosockets, are enabled in this context.

This hook, together with the ssl_session_store_by_lua* hook, can be used to implement distributed caching mechanisms in pure Lua (based on the cosocket API, for example). If a cached SSL session is found and loaded into the current SSL connection context, SSL session resumption can then get immediately initiated and bypass the full SSL handshake process which is very expensive in terms of CPU time.

Please note that TLS session tickets are very different and it is the clients' responsibility to cache the SSL session state when session tickets are used. SSL session resumptions based on TLS session tickets would happen automatically without going through this hook (nor thessl_session_store_by_lua* hook). This hook is mainly for older or less capable SSL clients that can only do SSL sessions by session IDs.

When ssl_certificate_by_lua* is specified at the same time, this hook usually runs before ssl_certificate_by_lua*. When the SSL session is found and successfully loaded for the current SSL connection, SSL session resumption will happen and thus bypass the ssl_certificate_by_lua*hook completely. In this case, Nginx also bypasses the ssl_session_store_by_lua*hook, for obvious reasons.

To easily test this hook locally with a modern web browser, you can temporarily put the following line in your https server block to disable the TLS session ticket support:

ssl\_session\_tickets off;

But do not forget to comment this line out before publishing your site to the world.

If you are using the official pre-built packages for OpenResty1.11.2.1 or later, then everything should work out of the box.

If you are not using one of the OpenSSL packages provided byOpenResty, you will need to apply patches to OpenSSL in order to use this directive:

https://openresty.org/en/openssl-patches.html

Similarly, if you are not using the Nginx core shipped withOpenResty 1.11.2.1 or later, you will need to apply patches to the standard Nginx core:

https://openresty.org/en/nginx-ssl-patches.html

This directive was first introduced in the

v0.10.6

release.

Note that this directive can only be used in the http context starting with the

v0.10.7

release since SSL session resumption happens before server name dispatch.

Back to TOC

ssl_session_fetch_by_lua_file

syntax: sslsessionfetchbylua_file <path-to-lua-script-file>

context: http

phase: right-before-SSL-handshake

Equivalent to ssl_session_fetch_by_lua_block, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or rather, the LuaJIT bytecode to be executed.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

This directive was first introduced in the

v0.10.6

release.

Note that: this directive is only allowed to used in http context from the

v0.10.7

release (because SSL session resumption happens before server name dispatch).

Back to TOC

ssl_session_store_by_lua_block

syntax: sslsessionstorebylua_block { lua-script }

context: http

phase: right-after-SSL-handshake

This directive runs Lua code to fetch and save the SSL session (if any) according to the session ID provided by the current SSL handshake request for the downstream. The saved or cached SSL session data can be used for future SSL connections to resume SSL sessions without going through the full SSL handshake process (which is very expensive in terms of CPU time).

Lua APIs that may yield, like ngx.sleep and cosockets, are disabled in this context. You can still, however, use the ngx.timer.at API to create 0-delay timers to save the SSL session data asynchronously to external services (like

redis

or

memcached

).

The Lua API for obtaining the current session ID and the associated session state data is provided in the ngx.ssl.sessionLua module shipped with the lua-resty-corelibrary.

To easily test this hook locally with a modern web browser, you can temporarily put the following line in your https server block to disable the TLS session ticket support:

ssl\_session\_tickets off;

But do not forget to comment this line out before publishing your site to the world.

This directive was first introduced in the

v0.10.6

release.

Note that: this directive is only allowed to used in http context from the

v0.10.7

release (because SSL session resumption happens before server name dispatch).

Back to TOC

ssl_session_store_by_lua_file

syntax: sslsessionstorebylua_file <path-to-lua-script-file>

context: http

phase: right-after-SSL-handshake

Equivalent to ssl_session_store_by_lua_block, except that the file specified by

<path-to-lua-script-file></path-to-lua-script-file>

contains the Lua code, or rather, the LuaJIT bytecode to be executed.

When a relative path like

foo/bar.lua

is given, they will be turned into the absolute path relative to the

server prefix

path determined by the

-p PATH

command-line option while starting the Nginx server.

This directive was first introduced in the

v0.10.6

release.

Note that: this directive is only allowed to used in http context from the

v0.10.7

release (because SSL session resumption happens before server name dispatch).

Back to TOC

lua_shared_dict

syntax: luashareddict <name> <size>

default: no

context: http

phase: depends on usage

Declares a shared memory zone,

<name></name>

, to serve as storage for the shm based Lua dictionary

ngx.shared.<name></name>

.

Shared memory zones are always shared by all the Nginx worker processes in the current Nginx server instance.

The

<size></size>

argument accepts size units such as

k

and

m

:

http { lua\_shared\_dict dogs 10m; ... }

The hard-coded minimum size is 8KB while the practical minimum size depends on actual user data set (some people start with 12KB).

See ngx.shared.DICT for details.

This directive was first introduced in the

v0.3.1rc22

release.

Back to TOC

lua_socket_connect_timeout

syntax: luasocketconnect_timeout <time>

default: luasocketconnect_timeout 60s

context: http, server, location

This directive controls the default timeout value used in TCP/unix-domain socket object's connect method and can be overridden by the settimeout or settimeouts methods.

The

<time></time>

argument can be an integer, with an optional time unit, like

s

(second),

ms

(millisecond),

m

(minute). The default time unit is

s

, i.e., "second". The default setting is

60s

.

This directive was first introduced in the

v0.5.0rc1

release.

Back to TOC

lua_socket_send_timeout

syntax: luasocketsend_timeout <time>

default: luasocketsend_timeout 60s

context: http, server, location

Controls the default timeout value used in TCP/unix-domain socket object's send method and can be overridden by the settimeout or settimeouts methods.

The

<time></time>

argument can be an integer, with an optional time unit, like

s

(second),

ms

(millisecond),

m

(minute). The default time unit is

s

, i.e., "second". The default setting is

60s

.

This directive was first introduced in the

v0.5.0rc1

release.

Back to TOC

lua_socket_send_lowat

syntax: luasocketsend_lowat <size>

default: luasocketsend_lowat 0

context: http, server, location

Controls the

lowat

(low water) value for the cosocket send buffer.

Back to TOC

lua_socket_read_timeout

syntax: luasocketread_timeout <time>

default: luasocketread_timeout 60s

context: http, server, location

phase: depends on usage

This directive controls the default timeout value used in TCP/unix-domain socket object's receive method and iterator functions returned by the receiveuntil method. This setting can be overridden by the settimeout or settimeouts methods.

The

<time></time>

argument can be an integer, with an optional time unit, like

s

(second),

ms

(millisecond),

m

(minute). The default time unit is

s

, i.e., "second". The default setting is

60s

.

This directive was first introduced in the

v0.5.0rc1

release.

Back to TOC

lua_socket_buffer_size

syntax: luasocketbuffer_size <size>

default: luasocketbuffer_size 4k/8k

context: http, server, location

Specifies the buffer size used by cosocket reading operations.

This buffer does not have to be that big to hold everything at the same time because cosocket supports 100% non-buffered reading and parsing. So even

1

byte buffer size should still work everywhere but the performance could be terrible.

This directive was first introduced in the

v0.5.0rc1

release.

Back to TOC

lua_socket_pool_size

syntax: luasocketpool_size <size>

default: luasocketpool_size 30

context: http, server, location

Specifies the size limit (in terms of connection count) for every cosocket connection pool associated with every remote server (i.e., identified by either the host-port pair or the unix domain socket file path).

Default to 30 connections for every pool.

When the connection pool exceeds the available size limit, the least recently used (idle) connection already in the pool will be closed to make room for the current connection.

Note that the cosocket connection pool is per Nginx worker process rather than per Nginx server instance, so size limit specified here also applies to every single Nginx worker process.

This directive was first introduced in the

v0.5.0rc1

release.

Back to TOC

lua_socket_keepalive_timeout

syntax: luasocketkeepalive_timeout <time>

default: luasocketkeepalive_timeout 60s

context: http, server, location

This directive controls the default maximal idle time of the connections in the cosocket built-in connection pool. When this timeout reaches, idle connections will be closed and removed from the pool. This setting can be overridden by cosocket objects' setkeepalive method.

The

<time></time>

argument can be an integer, with an optional time unit, like

s

(second),

ms

(millisecond),

m

(minute). The default time unit is

s

, i.e., "second". The default setting is

60s

.

This directive was first introduced in the

v0.5.0rc1

release.

Back to TOC

lua_socket_log_errors

syntax: luasocketlog_errors on|off

default: luasocketlog_errors on

context: http, server, location

This directive can be used to toggle error logging when a failure occurs for the TCP or UDP cosockets. If you are already doing proper error handling and logging in your Lua code, then it is recommended to turn this directive off to prevent data flushing in your Nginx error log files (which is usually rather expensive).

This directive was first introduced in the

v0.5.13

release.

Back to TOC

lua_ssl_ciphers

syntax: luasslciphers <ciphers>

default: luasslciphers DEFAULT

context: http, server, location

Specifies the enabled ciphers for requests to a SSL/TLS server in the tcpsock:sslhandshake method. The ciphers are specified in the format understood by the OpenSSL library.

The full list can be viewed using the “openssl ciphers” command.

This directive was first introduced in the

v0.9.11

release.

Back to TOC

lua_ssl_crl

syntax: luasslcrl <file>

default: no

context: http, server, location

Specifies a file with revoked certificates (CRL) in the PEM format used to verify the certificate of the SSL/TLS server in the tcpsock:sslhandshake method.

This directive was first introduced in the

v0.9.11

release.

Back to TOC

lua_ssl_protocols

syntax: luasslprotocols [SSLv2] [SSLv3] [TLSv1] [TLSv1.1] [TLSv1.2] [TLSv1.3]

default: luasslprotocols SSLv3 TLSv1 TLSv1.1 TLSv1.2

context: http, server, location

Enables the specified protocols for requests to a SSL/TLS server in the tcpsock:sslhandshake method.

The support for the

TLSv1.3

parameter requires version

v0.10.12

and OpenSSL 1.1.1.

This directive was first introduced in the

v0.9.11

release.

Back to TOC

lua_ssl_trusted_certificate

syntax: luassltrusted_certificate <file>

default: no

context: http, server, location

Specifies a file path with trusted CA certificates in the PEM format used to verify the certificate of the SSL/TLS server in the tcpsock:sslhandshake method.

This directive was first introduced in the

v0.9.11

release.

See also lua_ssl_verify_depth.

Back to TOC

lua_ssl_verify_depth

syntax: luasslverify_depth <number>

default: luasslverify_depth 1

context: http, server, location

Sets the verification depth in the server certificates chain.

This directive was first introduced in the

v0.9.11

release.

See also lua_ssl_trusted_certificate.

Back to TOC

lua_http10_buffering

syntax: luahttp10buffering on|off

default: luahttp10buffering on

context: http, server, location, location-if

Enables or disables automatic response buffering for HTTP 1.0 (or older) requests. This buffering mechanism is mainly used for HTTP 1.0 keep-alive which relies on a proper

Content-Length

response header.

If the Lua code explicitly sets a

Content-Length

response header before sending the headers (either explicitly via ngx.send_headers or implicitly via the first ngx.say or ngx.print call), then the HTTP 1.0 response buffering will be disabled even when this directive is turned on.

To output very large response data in a streaming fashion (via the ngx.flush call, for example), this directive MUST be turned off to minimize memory usage.

This directive is turned

on

by default.

This directive was first introduced in the

v0.5.0rc19

release.

Back to TOC

rewrite_by_lua_no_postpone

syntax: rewritebyluanopostpone on|off

default: rewritebyluanopostpone off

context: http

Controls whether or not to disable postponing rewrite_by_lua* directives to run at the end of the

rewrite

request-processing phase. By default, this directive is turned off and the Lua code is postponed to run at the end of the

rewrite

phase.

This directive was first introduced in the

v0.5.0rc29

release.

Back to TOC

access_by_lua_no_postpone

syntax: accessbyluanopostpone on|off

default: accessbyluanopostpone off

context: http

Controls whether or not to disable postponing access_by_lua* directives to run at the end of the

access

request-processing phase. By default, this directive is turned off and the Lua code is postponed to run at the end of the

access

phase.

This directive was first introduced in the

v0.9.20

release.

Back to TOC

lua_transform_underscores_in_response_headers

syntax: luatransformunderscoresinresponse_headers on|off

default: luatransformunderscoresinresponse_headers on

context: http, server, location, location-if

Controls whether to transform underscores (

\_

) in the response header names specified in the ngx.header.HEADER API to hypens (

-

).

This directive was first introduced in the

v0.5.0rc32

release.

Back to TOC

lua_check_client_abort

syntax: luacheckclient_abort on|off

default: luacheckclient_abort off

context: http, server, location, location-if

This directive controls whether to check for premature client connection abortion.

When this directive is on, the ngx_lua module will monitor the premature connection close event on the downstream connections and when there is such an event, it will call the user Lua function callback (registered by ngx.on_abort) or just stop and clean up all the Lua "light threads" running in the current request's request handler when there is no user callback function registered.

According to the current implementation, however, if the client closes the connection before the Lua code finishes reading the request body data via ngx.req.socket, then ngx_lua will neither stop all the running "light threads" nor call the user callback (if ngx.on_abort has been called). Instead, the reading operation on ngx.req.socket will just return the error message "client aborted" as the second return value (the first return value is surely

nil

).

When TCP keepalive is disabled, it is relying on the client side to close the socket gracefully (by sending a

FIN

packet or something like that). For (soft) real-time web applications, it is highly recommended to configure the TCP keepalive support in your system's TCP stack implementation in order to detect "half-open" TCP connections in time.

For example, on Linux, you can configure the standard listen directive in your

nginx.conf

file like this:

listen 80 so\_keepalive=2s:2s:8;

On FreeBSD, you can only tune the system-wide configuration for TCP keepalive, for example:

# sysctl net.inet.tcp.keepintvl=2000 # sysctl net.inet.tcp.keepidle=2000

This directive was first introduced in the

v0.7.4

release.

See also ngx.on_abort.

Back to TOC

lua_max_pending_timers

syntax: luamaxpending_timers <count>

default: luamaxpending_timers 1024

context: http

Controls the maximum number of pending timers allowed.

Pending timers are those timers that have not expired yet.

When exceeding this limit, the ngx.timer.at call will immediately return

nil

and the error string "too many pending timers".

This directive was first introduced in the

v0.8.0

release.

Back to TOC

lua_max_running_timers

syntax: luamaxrunning_timers <count>

default: luamaxrunning_timers 256

context: http

Controls the maximum number of "running timers" allowed.

Running timers are those timers whose user callback functions are still running.

When exceeding this limit, Nginx will stop running the callbacks of newly expired timers and log an error message "N lua_max_running_timers are not enough" where "N" is the current value of this directive.

This directive was first introduced in the

v0.8.0

release.

Back to TOC

lua_sa_restart

syntax: luasarestart on|off

default: luasarestart on

context: http

When enabled, this module will set the

SA\_RESTART

flag on Nginx workers signal dispositions.

This allows Lua I/O primitives to not be interrupted by Nginx's handling of various signals.

This directive was first introduced in the

v0.10.14

release.

Back to TOC

Nginx API for Lua

Back to TOC

Introduction

The various

\*\_by\_lua

,

\*\_by\_lua\_block

and

\*\_by\_lua\_file

configuration directives serve as gateways to the Lua API within the

nginx.conf

file. The Nginx Lua API described below can only be called within the user Lua code run in the context of these configuration directives.

The API is exposed to Lua in the form of two standard packages

ngx

and

ndk

. These packages are in the default global scope within ngx_lua and are always available within ngx_lua directives.

The packages can be introduced into external Lua modules like this:

local say = ngx.say local \_M = {} function \_M.foo(a) say(a) end return \_M

Use of the package.seeall flag is strongly discouraged due to its various bad side-effects.

It is also possible to directly require the packages in external Lua modules:

local ngx = require "ngx" local ndk = require "ndk"

The ability to require these packages was introduced in the

v0.2.1rc19

release.

Network I/O operations in user code should only be done through the Nginx Lua API calls as the Nginx event loop may be blocked and performance drop off dramatically otherwise. Disk operations with relatively small amount of data can be done using the standard Lua

io

library but huge file reading and writing should be avoided wherever possible as they may block the Nginx process significantly. Delegating all network and disk I/O operations to Nginx's subrequests (via the ngx.location.capture method and similar) is strongly recommended for maximum performance.

Back to TOC

ngx.arg

syntax: val = ngx.arg[index]

context: setbylua*, bodyfilterby_lua*

When this is used in the context of the set_by_lua* directives, this table is read-only and holds the input arguments to the config directives:

value = ngx.arg[n]

Here is an example

location /foo { set $a 32; set $b 56; set\_by\_lua $sum 'return tonumber(ngx.arg[1]) + tonumber(ngx.arg[2])' $a $b; echo $sum; }

that writes out

88

, the sum of

32

and

56

.

When this table is used in the context of body_filter_by_lua*, the first element holds the input data chunk to the output filter code and the second element holds the boolean flag for the "eof" flag indicating the end of the whole output data stream.

The data chunk and "eof" flag passed to the downstream Nginx output filters can also be overridden by assigning values directly to the corresponding table elements. When setting

nil

or an empty Lua string value to

ngx.arg[1]

, no data chunk will be passed to the downstream Nginx output filters at all.

Back to TOC

ngx.var.VARIABLE

syntax: ngx.var.VAR_NAME

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*

Read and write Nginx variable values.

value = ngx.var.some\_nginx\_variable\_name ngx.var.some\_nginx\_variable\_name = value

Note that only already defined Nginx variables can be written to. For example:

location /foo { set $my\_var ''; # this line is required to create $my\_var at config time content\_by\_lua\_block { ngx.var.my\_var = 123; ... } }

That is, Nginx variables cannot be created on-the-fly.

Some special Nginx variables like

$args

and

$limit\_rate

can be assigned a value, many others are not, like

$query\_string

,

$arg\_PARAMETER

, and

$http\_NAME

.

Nginx regex group capturing variables

$1

,

$2

,

$3

, and etc, can be read by this interface as well, by writing

ngx.var[1]

,

ngx.var[2]

,

ngx.var[3]

, and etc.

Setting

ngx.var.Foo

to a

nil

value will unset the

$Foo

Nginx variable.

ngx.var.args = nil

CAUTION When reading from an Nginx variable, Nginx will allocate memory in the per-request memory pool which is freed only at request termination. So when you need to read from an Nginx variable repeatedly in your Lua code, cache the Nginx variable value to your own Lua variable, for example,

local val = ngx.var.some\_var --- use the val repeatedly later

to prevent (temporary) memory leaking within the current request's lifetime. Another way of caching the result is to use the ngx.ctx table.

Undefined Nginx variables are evaluated to

nil

while uninitialized (but defined) Nginx variables are evaluated to an empty Lua string.

This API requires a relatively expensive metamethod call and it is recommended to avoid using it on hot code paths.

Back to TOC

Core constants

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, *logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

ngx.OK (0) ngx.ERROR (-1) ngx.AGAIN (-2) ngx.DONE (-4) ngx.DECLINED (-5)

Note that only three of these constants are utilized by the Nginx API for Lua (i.e., ngx.exit accepts

ngx.OK

,

ngx.ERROR

, and

ngx.DECLINED

as input).

ngx.null

The

ngx.null

constant is a

NULL

light userdata usually used to represent nil values in Lua tables etc and is similar to the lua-cjson library's

cjson.null

constant. This constant was first introduced in the

v0.5.0rc5

release.

The

ngx.DECLINED

constant was first introduced in the

v0.5.0rc19

release.

Back to TOC

HTTP method constants

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

ngx.HTTP\_GET ngx.HTTP\_HEAD ngx.HTTP\_PUT ngx.HTTP\_POST ngx.HTTP\_DELETE ngx.HTTP\_OPTIONS (added in the v0.5.0rc24 release) ngx.HTTP\_MKCOL (added in the v0.8.2 release) ngx.HTTP\_COPY (added in the v0.8.2 release) ngx.HTTP\_MOVE (added in the v0.8.2 release) ngx.HTTP\_PROPFIND (added in the v0.8.2 release) ngx.HTTP\_PROPPATCH (added in the v0.8.2 release) ngx.HTTP\_LOCK (added in the v0.8.2 release) ngx.HTTP\_UNLOCK (added in the v0.8.2 release) ngx.HTTP\_PATCH (added in the v0.8.2 release) ngx.HTTP\_TRACE (added in the v0.8.2 release)

These constants are usually used in ngx.location.capture and ngx.location.capture_multi method calls.

Back to TOC

HTTP status constants

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

value = ngx.HTTP\_CONTINUE (100) (first added in the v0.9.20 release) value = ngx.HTTP\_SWITCHING\_PROTOCOLS (101) (first added in the v0.9.20 release) value = ngx.HTTP\_OK (200) value = ngx.HTTP\_CREATED (201) value = ngx.HTTP\_ACCEPTED (202) (first added in the v0.9.20 release) value = ngx.HTTP\_NO\_CONTENT (204) (first added in the v0.9.20 release) value = ngx.HTTP\_PARTIAL\_CONTENT (206) (first added in the v0.9.20 release) value = ngx.HTTP\_SPECIAL\_RESPONSE (300) value = ngx.HTTP\_MOVED\_PERMANENTLY (301) value = ngx.HTTP\_MOVED\_TEMPORARILY (302) value = ngx.HTTP\_SEE\_OTHER (303) value = ngx.HTTP\_NOT\_MODIFIED (304) value = ngx.HTTP\_TEMPORARY\_REDIRECT (307) (first added in the v0.9.20 release) value = ngx.HTTP\_PERMANENT\_REDIRECT (308) value = ngx.HTTP\_BAD\_REQUEST (400) value = ngx.HTTP\_UNAUTHORIZED (401) value = ngx.HTTP\_PAYMENT\_REQUIRED (402) (first added in the v0.9.20 release) value = ngx.HTTP\_FORBIDDEN (403) value = ngx.HTTP\_NOT\_FOUND (404) value = ngx.HTTP\_NOT\_ALLOWED (405) value = ngx.HTTP\_NOT\_ACCEPTABLE (406) (first added in the v0.9.20 release) value = ngx.HTTP\_REQUEST\_TIMEOUT (408) (first added in the v0.9.20 release) value = ngx.HTTP\_CONFLICT (409) (first added in the v0.9.20 release) value = ngx.HTTP\_GONE (410) value = ngx.HTTP\_UPGRADE\_REQUIRED (426) (first added in the v0.9.20 release) value = ngx.HTTP\_TOO\_MANY\_REQUESTS (429) (first added in the v0.9.20 release) value = ngx.HTTP\_CLOSE (444) (first added in the v0.9.20 release) value = ngx.HTTP\_ILLEGAL (451) (first added in the v0.9.20 release) value = ngx.HTTP\_INTERNAL\_SERVER\_ERROR (500) value = ngx.HTTP\_METHOD\_NOT\_IMPLEMENTED (501) value = ngx.HTTP\_BAD\_GATEWAY (502) (first added in the v0.9.20 release) value = ngx.HTTP\_SERVICE\_UNAVAILABLE (503) value = ngx.HTTP\_GATEWAY\_TIMEOUT (504) (first added in the v0.3.1rc38 release) value = ngx.HTTP\_VERSION\_NOT\_SUPPORTED (505) (first added in the v0.9.20 release) value = ngx.HTTP\_INSUFFICIENT\_STORAGE (507) (first added in the v0.9.20 release)

Back to TOC

Nginx log level constants

context: initbylua*, initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

ngx.STDERR ngx.EMERG ngx.ALERT ngx.CRIT ngx.ERR ngx.WARN ngx.NOTICE ngx.INFO ngx.DEBUG

These constants are usually used by the ngx.log method.

Back to TOC

print

syntax: print(...)

context: initbylua*, initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Writes argument values into the Nginx

error.log

file with the

ngx.NOTICE

log level.

It is equivalent to

ngx.log(ngx.NOTICE, ...)

Lua

nil

arguments are accepted and result in literal

"nil"

strings while Lua booleans result in literal

"true"

or

"false"

strings. And the

ngx.null

constant will yield the

"null"

string output.

There is a hard coded

2048

byte limitation on error message lengths in the Nginx core. This limit includes trailing newlines and leading time stamps. If the message size exceeds this limit, Nginx will truncate the message text accordingly. This limit can be manually modified by editing the

NGX\_MAX\_ERROR\_STR

macro definition in the

src/core/ngx\_log.h

file in the Nginx source tree.

Back to TOC

ngx.ctx

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerby_lua*

This table can be used to store per-request Lua context data and has a life time identical to the current request (as with the Nginx variables).

Consider the following example,

location /test { rewrite\_by\_lua\_block { ngx.ctx.foo = 76 } access\_by\_lua\_block { ngx.ctx.foo = ngx.ctx.foo + 3 } content\_by\_lua\_block { ngx.say(ngx.ctx.foo) } }

Then

GET /test

will yield the output

79

That is, the

ngx.ctx.foo

entry persists across the rewrite, access, and content phases of a request.

Every request, including subrequests, has its own copy of the table. For example:

location /sub { content\_by\_lua\_block { ngx.say("sub pre: ", ngx.ctx.blah) ngx.ctx.blah = 32 ngx.say("sub post: ", ngx.ctx.blah) } } location /main { content\_by\_lua\_block { ngx.ctx.blah = 73 ngx.say("main pre: ", ngx.ctx.blah) local res = ngx.location.capture("/sub") ngx.print(res.body) ngx.say("main post: ", ngx.ctx.blah) } }

Then

GET /main

will give the output

main pre: 73 sub pre: nil sub post: 32 main post: 73

Here, modification of the

ngx.ctx.blah

entry in the subrequest does not affect the one in the parent request. This is because they have two separate versions of

ngx.ctx.blah

.

Internal redirection will destroy the original request

ngx.ctx

data (if any) and the new request will have an empty

ngx.ctx

table. For instance,

location /new { content\_by\_lua\_block { ngx.say(ngx.ctx.foo) } } location /orig { content\_by\_lua\_block { ngx.ctx.foo = "hello" ngx.exec("/new") } }

Then

GET /orig

will give

nil

rather than the original

"hello"

value.

Arbitrary data values, including Lua closures and nested tables, can be inserted into this "magic" table. It also allows the registration of custom meta methods.

Overriding

ngx.ctx

with a new Lua table is also supported, for example,

ngx.ctx = { foo = 32, bar = 54 }

When being used in the context of init_worker_by_lua*, this table just has the same lifetime of the current Lua handler.

The

ngx.ctx

lookup requires relatively expensive metamethod calls and it is much slower than explicitly passing per-request data along by your own function arguments. So do not abuse this API for saving your own function arguments because it usually has quite some performance impact.

Because of the metamethod magic, never "local" the

ngx.ctx

table outside your Lua function scope on the Lua module level due to worker-level data sharing. For example, the following is bad:

-- mymodule.lua local \_M = {} -- the following line is bad since ngx.ctx is a per-request -- data while this ctx variable is on the Lua module level -- and thus is per-nginx-worker. local ctx = ngx.ctx function \_M.main() ctx.foo = "bar" end return \_M

Use the following instead:

-- mymodule.lua local \_M = {} function \_M.main(ctx) ctx.foo = "bar" end return \_M

That is, let the caller pass the

ctx

table explicitly via a function argument.

Back to TOC

ngx.location.capture

syntax: res = ngx.location.capture(uri, options?)

context: rewritebylua*, accessbylua*, contentbylua*

Issues a synchronous but still non-blocking Nginx Subrequest using

uri

.

Nginx's subrequests provide a powerful way to make non-blocking internal requests to other locations configured with disk file directory or any other Nginx C modules like

ngx\_proxy

,

ngx\_fastcgi

,

ngx\_memc

,

ngx\_postgres

,

ngx\_drizzle

, and even ngx_lua itself and etc etc etc.

Also note that subrequests just mimic the HTTP interface but there is no extra HTTP/TCP traffic nor IPC involved. Everything works internally, efficiently, on the C level.

Subrequests are completely different from HTTP 301/302 redirection (via ngx.redirect) and internal redirection (via ngx.exec).

You should always read the request body (by either calling ngx.req.read_body or configuring lua_need_request_body on) before initiating a subrequest.

This API function (as well as ngx.location.capture_multi) always buffers the whole response body of the subrequest in memory. Thus, you should use cosocketsand streaming processing instead if you have to handle large subrequest responses.

Here is a basic example:

res = ngx.location.capture(uri)

Returns a Lua table with 4 slots:

res.status

,

res.header

,

res.body

, and

res.truncated

.

res.status

holds the response status code for the subrequest response.

res.header

holds all the response headers of the subrequest and it is a normal Lua table. For multi-value response headers, the value is a Lua (array) table that holds all the values in the order that they appear. For instance, if the subrequest response headers contain the following lines:

Set-Cookie: a=3 Set-Cookie: foo=bar Set-Cookie: baz=blah

Then

res.header["Set-Cookie"]

will be evaluated to the table value

{"a=3", "foo=bar", "baz=blah"}

.

res.body

holds the subrequest's response body data, which might be truncated. You always need to check the

res.truncated

boolean flag to see if

res.body

contains truncated data. The data truncation here can only be caused by those unrecoverable errors in your subrequests like the cases that the remote end aborts the connection prematurely in the middle of the response body data stream or a read timeout happens when your subrequest is receiving the response body data from the remote.

URI query strings can be concatenated to URI itself, for instance,

res = ngx.location.capture('/foo/bar?a=3&b=4')

Named locations like

@foo

are not allowed due to a limitation in the Nginx core. Use normal locations combined with the

internal

directive to prepare internal-only locations.

An optional option table can be fed as the second argument, which supports the options:

  • method
    specify the subrequest's request method, which only accepts constants like
    ngx.HTTP\_POST
    .
  • body
    specify the subrequest's request body (string value only).
  • args
    specify the subrequest's URI query arguments (both string value and Lua tables are accepted)
  • ctx
    specify a Lua table to be the ngx.ctx table for the subrequest. It can be the current request's ngx.ctx table, which effectively makes the parent and its subrequest to share exactly the same context table. This option was first introduced in the
    v0.3.1rc25
    release.
  • vars
    take a Lua table which holds the values to set the specified Nginx variables in the subrequest as this option's value. This option was first introduced in the
    v0.3.1rc31
    release.
  • copy\_all\_vars
    specify whether to copy over all the Nginx variable values of the current request to the subrequest in question. modifications of the Nginx variables in the subrequest will not affect the current (parent) request. This option was first introduced in the
    v0.3.1rc31
    release.
  • share\_all\_vars
    specify whether to share all the Nginx variables of the subrequest with the current (parent) request. modifications of the Nginx variables in the subrequest will affect the current (parent) request. Enabling this option may lead to hard-to-debug issues due to bad side-effects and is considered bad and harmful. Only enable this option when you completely know what you are doing.
  • always\_forward\_body
    when set to true, the current (parent) request's request body will always be forwarded to the subrequest being created if the
    body
    option is not specified. The request body read by either ngx.req.read_body() or lua_need_request_body on will be directly forwarded to the subrequest without copying the whole request body data when creating the subrequest (no matter the request body data is buffered in memory buffers or temporary files). By default, this option is
    false
    and when the
    body
    option is not specified, the request body of the current (parent) request is only forwarded when the subrequest takes the
    PUT
    or
    POST
    request method.

Issuing a POST subrequest, for example, can be done as follows

res = ngx.location.capture( '/foo/bar', { method = ngx.HTTP\_POST, body = 'hello, world' } )

See HTTP method constants methods other than POST. The

method

option is

ngx.HTTP\_GET

by default.

The

args

option can specify extra URI arguments, for instance,

ngx.location.capture('/foo?a=1', { args = { b = 3, c = ':' } } )

is equivalent to

ngx.location.capture('/foo?a=1&b=3&c=%3a')

that is, this method will escape argument keys and values according to URI rules and concatenate them together into a complete query string. The format for the Lua table passed as the

args

argument is identical to the format used in the ngx.encode_args method.

The

args

option can also take plain query strings:

ngx.location.capture('/foo?a=1', { args = 'b=3&c=%3a' } )

This is functionally identical to the previous examples.

The

share\_all\_vars

option controls whether to share Nginx variables among the current request and its subrequests. If this option is set to

true

, then the current request and associated subrequests will share the same Nginx variable scope. Hence, changes to Nginx variables made by a subrequest will affect the current request.

Care should be taken in using this option as variable scope sharing can have unexpected side effects. The

args

,

vars

, or

copy\_all\_vars

options are generally preferable instead.

This option is set to

false

by default

location /other { set $dog "$dog world"; echo "$uri dog: $dog"; } location /lua { set $dog 'hello'; content\_by\_lua\_block { res = ngx.location.capture("/other", { share\_all\_vars = true }); ngx.print(res.body) ngx.say(ngx.var.uri, ": ", ngx.var.dog) } }

Accessing location

/lua

gives

/other dog: hello world /lua: hello world

The

copy\_all\_vars

option provides a copy of the parent request's Nginx variables to subrequests when such subrequests are issued. Changes made to these variables by such subrequests will not affect the parent request or any other subrequests sharing the parent request's variables.

location /other { set $dog "$dog world"; echo "$uri dog: $dog"; } location /lua { set $dog 'hello'; content\_by\_lua\_block { res = ngx.location.capture("/other", { copy\_all\_vars = true }); ngx.print(res.body) ngx.say(ngx.var.uri, ": ", ngx.var.dog) } }

Request

GET /lua

will give the output

/other dog: hello world /lua: hello

Note that if both

share\_all\_vars

and

copy\_all\_vars

are set to true, then

share\_all\_vars

takes precedence.

In addition to the two settings above, it is possible to specify values for variables in the subrequest using the

vars

option. These variables are set after the sharing or copying of variables has been evaluated, and provides a more efficient method of passing specific values to a subrequest over encoding them as URL arguments and unescaping them in the Nginx config file.

location /other { content\_by\_lua\_block { ngx.say("dog = ", ngx.var.dog) ngx.say("cat = ", ngx.var.cat) } } location /lua { set $dog ''; set $cat ''; content\_by\_lua\_block { res = ngx.location.capture("/other", { vars = { dog = "hello", cat = 32 }}); ngx.print(res.body) } }

Accessing

/lua

will yield the output

dog = hello cat = 32

The

ctx

option can be used to specify a custom Lua table to serve as the ngx.ctx table for the subrequest.

location /sub { content\_by\_lua\_block { ngx.ctx.foo = "bar"; } } location /lua { content\_by\_lua\_block { local ctx = {} res = ngx.location.capture("/sub", { ctx = ctx }) ngx.say(ctx.foo); ngx.say(ngx.ctx.foo); } }

Then request

GET /lua

gives

bar nil

It is also possible to use this

ctx

option to share the same ngx.ctx table between the current (parent) request and the subrequest:

location /sub { content\_by\_lua\_block { ngx.ctx.foo = "bar"; } } location /lua { content\_by\_lua\_block { res = ngx.location.capture("/sub", { ctx = ngx.ctx }) ngx.say(ngx.ctx.foo); } }

Request

GET /lua

yields the output

bar

Note that subrequests issued by ngx.location.capture inherit all the request headers of the current request by default and that this may have unexpected side effects on the subrequest responses. For example, when using the standard

ngx\_proxy

module to serve subrequests, an "Accept-Encoding: gzip" header in the main request may result in gzipped responses that cannot be handled properly in Lua code. Original request headers should be ignored by settingproxy_pass_request_headers to

off

in subrequest locations.

When the

body

option is not specified and the

always\_forward\_body

option is false (the default value), the

POST

and

PUT

subrequests will inherit the request bodies of the parent request (if any).

There is a hard-coded upper limit on the number of subrequests possible for every main request. In older versions of Nginx, the limit was

50

concurrent subrequests and in more recent versions, Nginx

1.9.5

onwards, the same limit is changed to limit the depth of recursive subrequests. When this limit is exceeded, the following error message is added to the

error.log

file:

[error] 13983#0: \*1 subrequests cycle while processing "/uri"

The limit can be manually modified if required by editing the definition of the

NGX\_HTTP\_MAX\_SUBREQUESTS

macro in the

nginx/src/http/ngx\_http\_request.h

file in the Nginx source tree.

Please also refer to restrictions on capturing locations configured by subrequest directives of other modules.

Back to TOC

ngx.location.capture_multi

syntax: res1, res2, ... = ngx.location.capture_multi({ {uri, options?}, {uri, options?}, ... })

context: rewritebylua*, accessbylua*, contentbylua*

Just like ngx.location.capture, but supports multiple subrequests running in parallel.

This function issues several parallel subrequests specified by the input table and returns their results in the same order. For example,

res1, res2, res3 = ngx.location.capture\_multi{ { "/foo", { args = "a=3&b=4" } }, { "/bar" }, { "/baz", { method = ngx.HTTP\_POST, body = "hello" } }, } if res1.status == ngx.HTTP\_OK then ... end if res2.body == "BLAH" then ... end

This function will not return until all the subrequests terminate. The total latency is the longest latency of the individual subrequests rather than the sum.

Lua tables can be used for both requests and responses when the number of subrequests to be issued is not known in advance:

-- construct the requests table local reqs = {} table.insert(reqs, { "/mysql" }) table.insert(reqs, { "/postgres" }) table.insert(reqs, { "/redis" }) table.insert(reqs, { "/memcached" }) -- issue all the requests at once and wait until they all return local resps = { ngx.location.capture\_multi(reqs) } -- loop over the responses table for i, resp in ipairs(resps) do -- process the response table "resp" end

The ngx.location.capture function is just a special form of this function. Logically speaking, the ngx.location.capture can be implemented like this

ngx.location.capture = function (uri, args) return ngx.location.capture\_multi({ {uri, args} }) end

Please also refer to restrictions on capturing locations configured by subrequest directives of other modules.

Back to TOC

ngx.status

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*

Read and write the current request's response status. This should be called before sending out the response headers.

ngx.status = ngx.HTTP\_CREATED status = ngx.status

Setting

ngx.status

after the response header is sent out has no effect but leaving an error message in your Nginx's error log file:

attempt to set ngx.status after sending out response headers

Back to TOC

ngx.header.HEADER

syntax: ngx.header.HEADER = VALUE

syntax: value = ngx.header.HEADER

context: rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*

Set, add to, or clear the current request's

HEADER

response header that is to be sent.

Underscores (

\_

) in the header names will be replaced by hyphens (

-

) by default. This transformation can be turned off via the lua_transform_underscores_in_response_headers directive.

The header names are matched case-insensitively.

-- equivalent to ngx.header["Content-Type"] = 'text/plain' ngx.header.content\_type = 'text/plain'; ngx.header["X-My-Header"] = 'blah blah';

Multi-value headers can be set this way:

ngx.header['Set-Cookie'] = {'a=32; path=/', 'b=4; path=/'}

will yield

Set-Cookie: a=32; path=/ Set-Cookie: b=4; path=/

in the response headers.

Only Lua tables are accepted (Only the last element in the table will take effect for standard headers such as

Content-Type

that only accept a single value).

ngx.header.content\_type = {'a', 'b'}

is equivalent to

ngx.header.content\_type = 'b'

Setting a slot to

nil

effectively removes it from the response headers:

ngx.header["X-My-Header"] = nil;

The same applies to assigning an empty table:

ngx.header["X-My-Header"] = {};

Setting

ngx.header.HEADER

after sending out response headers (either explicitly with ngx.send_headers or implicitly with ngx.print and similar) will log an error message.

Reading

ngx.header.HEADER

will return the value of the response header named

HEADER

.

Underscores (

\_

) in the header names will also be replaced by dashes (

-

) and the header names will be matched case-insensitively. If the response header is not present at all,

nil

will be returned.

This is particularly useful in the context of header_filter_by_lua*, for example,

location /test { set $footer ''; proxy\_pass http://some-backend; header\_filter\_by\_lua\_block { if ngx.header["X-My-Header"] == "blah" then ngx.var.footer = "some value" end } echo\_after\_body $footer; }

For multi-value headers, all of the values of header will be collected in order and returned as a Lua table. For example, response headers

Foo: bar Foo: baz

will result in

{"bar", "baz"}

to be returned when reading

ngx.header.Foo

.

Note that

ngx.header

is not a normal Lua table and as such, it is not possible to iterate through it using the Lua

ipairs

function.

Note: this function throws a Lua error if

HEADER

or

VALUE

contain unsafe characters (control characters).

For reading request headers, use the ngx.req.get_headers function instead.

Back to TOC

ngx.resp.get_headers

syntax: headers, err = ngx.resp.getheaders(maxheaders?, raw?)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, balancerbylua*

Returns a Lua table holding all the current response headers for the current request.

local h, err = ngx.resp.get\_headers() if err == "truncated" then -- one can choose to ignore or reject the current response here end for k, v in pairs(h) do ... end

This function has the same signature as ngx.req.get_headers except getting response headers instead of request headers.

Note that a maximum of 100 response headers are parsed by default (including those with the same name) and that additional response headers are silently discarded to guard against potential denial of service attacks. Since

v0.10.13

, when the limit is exceeded, it will return a second value which is the string

"truncated"

.

This API was first introduced in the

v0.9.5

release.

Back to TOC

ngx.req.is_internal

syntax: isinternal = ngx.req.isinternal()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*

Returns a boolean indicating whether the current request is an "internal request", i.e., a request initiated from inside the current Nginx server instead of from the client side.

Subrequests are all internal requests and so are requests after internal redirects.

This API was first introduced in the

v0.9.20

release.

Back to TOC

ngx.req.start_time

syntax: secs = ngx.req.start_time()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*

Returns a floating-point number representing the timestamp (including milliseconds as the decimal part) when the current request was created.

The following example emulates the

$request\_time

variable value (provided by ngx_http_log_module) in pure Lua:

local request\_time = ngx.now() - ngx.req.start\_time()

This function was first introduced in the

v0.7.7

release.

See also ngx.now and ngx.update_time.

Back to TOC

ngx.req.http_version

syntax: num = ngx.req.http_version()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterby_lua*

Returns the HTTP version number for the current request as a Lua number.

Current possible values are 2.0, 1.0, 1.1, and 0.9. Returns

nil

for unrecognized values.

This method was first introduced in the

v0.7.17

release.

Back to TOC

ngx.req.raw_header

syntax: str = ngx.req.rawheader(norequest_line?)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterby_lua*

Returns the original raw HTTP protocol header received by the Nginx server.

By default, the request line and trailing

CR LF

terminator will also be included. For example,

ngx.print(ngx.req.raw\_header())

gives something like this:

GET /t HTTP/1.1 Host: localhost Connection: close Foo: bar

You can specify the optional

no\_request\_line

argument as a

true

value to exclude the request line from the result. For example,

ngx.print(ngx.req.raw\_header(true))

outputs something like this:

Host: localhost Connection: close Foo: bar

This method was first introduced in the

v0.7.17

release.

This method does not work in HTTP/2 requests yet.

Back to TOC

ngx.req.get_method

syntax: methodname = ngx.req.getmethod()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, balancerbylua*, logbylua*

Retrieves the current request's request method name. Strings like

"GET"

and

"POST"

are returned instead of numerical method constants.

If the current request is an Nginx subrequest, then the subrequest's method name will be returned.

This method was first introduced in the

v0.5.6

release.

See also ngx.req.set_method.

Back to TOC

ngx.req.set_method

syntax: ngx.req.setmethod(methodid)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterby_lua*

Overrides the current request's request method with the

method\_id

argument. Currently only numerical method constants are supported, like

ngx.HTTP\_POST

and

ngx.HTTP\_GET

.

If the current request is an Nginx subrequest, then the subrequest's method will be overridden.

This method was first introduced in the

v0.5.6

release.

See also ngx.req.get_method.

Back to TOC

ngx.req.set_uri

syntax: ngx.req.set_uri(uri, jump?, binary?)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*

Rewrite the current request's (parsed) URI by the

uri

argument. The

uri

argument must be a Lua string and cannot be of zero length, or a Lua exception will be thrown.

The optional boolean

jump

argument can trigger location rematch (or location jump) as ngx_http_rewrite_module's rewrite directive, that is, when

jump

is

true

(default to

false

), this function will never return and it will tell Nginx to try re-searching locations with the new URI value at the later

post-rewrite

phase and jumping to the new location.

Location jump will not be triggered otherwise, and only the current request's URI will be modified, which is also the default behavior. This function will return but with no returned values when the

jump

argument is

false

or absent altogether.

For example, the following Nginx config snippet

rewrite ^ /foo last;

can be coded in Lua like this:

ngx.req.set\_uri("/foo", true)

Similarly, Nginx config

rewrite ^ /foo break;

can be coded in Lua as

ngx.req.set\_uri("/foo", false)

or equivalently,

ngx.req.set\_uri("/foo")

The

jump

argument can only be set to

true

in rewrite_by_lua*. Use of jump in other contexts is prohibited and will throw out a Lua exception.

A more sophisticated example involving regex substitutions is as follows

location /test { rewrite\_by\_lua\_block { local uri = ngx.re.sub(ngx.var.uri, "^/test/(.\*)", "/$1", "o") ngx.req.set\_uri(uri) } proxy\_pass http://my\_backend; }

which is functionally equivalent to

location /test { rewrite ^/test/(.\*) /$1 break; proxy\_pass http://my\_backend; }

Note: this function throws a Lua error if the

uri

argument contains unsafe characters (control characters).

Note that it is not possible to use this interface to rewrite URI arguments and that ngx.req.set_uri_args should be used for this instead. For instance, Nginx config

rewrite ^ /foo?a=3? last;

can be coded as

ngx.req.set\_uri\_args("a=3") ngx.req.set\_uri("/foo", true)

or

ngx.req.set\_uri\_args({a = 3}) ngx.req.set\_uri("/foo", true)

Starting from

0.10.16

of this module, this function accepts an optional boolean

binary

argument to allow arbitrary binary URI data. By default, this

binary

argument is false and this function will throw out a Lua error such as the one below when the

uri

argument contains any control characters (ASCII Code 0 ~ 0x08, 0x0A ~ 0x1F and 0x7F).

[error] 23430#23430: \*1 lua entry thread aborted: runtime error: content\_by\_lua(nginx.conf:44):3: ngx.req.set\_uri unsafe byte "0x00" in "\x00foo" (maybe you want to set the 'binary' argument?)

This interface was first introduced in the

v0.3.1rc14

release.

Back to TOC

ngx.req.set_uri_args

syntax: ngx.req.seturiargs(args)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*

Rewrite the current request's URI query arguments by the

args

argument. The

args

argument can be either a Lua string, as in

ngx.req.set\_uri\_args("a=3&b=hello%20world")

or a Lua table holding the query arguments' key-value pairs, as in

ngx.req.set\_uri\_args({ a = 3, b = "hello world" })

In the former case, i.e., when the whole query-string is provided directly, the input Lua string should already be well-formed with the URI encoding. For security considerations, this method will automatically escape any control and whitespace characters (ASCII code 0x00 ~ 0x20 and 0x7F) in the Lua string.

In the latter case, this method will escape argument keys and values according to the URI escaping rule.

Multi-value arguments are also supported:

ngx.req.set\_uri\_args({ a = 3, b = {5, 6} })

which will result in a query string like

a=3&b=5&b=6

.

This interface was first introduced in the

v0.3.1rc13

release.

See also ngx.req.set_uri.

Back to TOC

ngx.req.get_uri_args

syntax: args, err = ngx.req.geturiargs(max_args?)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, balancerbylua*

Returns a Lua table holding all the current request URL query arguments.

location = /test { content\_by\_lua\_block { local args, err = ngx.req.get\_uri\_args() if err == "truncated" then -- one can choose to ignore or reject the current request here end for key, val in pairs(args) do if type(val) == "table" then ngx.say(key, ": ", table.concat(val, ", ")) else ngx.say(key, ": ", val) end end } }

Then

GET /test?foo=bar&bar=baz&bar=blah

will yield the response body

foo: bar bar: baz, blah

Multiple occurrences of an argument key will result in a table value holding all the values for that key in order.

Keys and values are unescaped according to URI escaping rules. In the settings above,

GET /test?a%20b=1%61+2

will yield:

a b: 1a 2

Arguments without the

=<value></value>

parts are treated as boolean arguments.

GET /test?foo&bar

will yield:

foo: true bar: true

That is, they will take Lua boolean values

true

. However, they are different from arguments taking empty string values.

GET /test?foo=&bar=

will give something like

foo: bar:

Empty key arguments are discarded.

GET /test?=hello&=world

will yield an empty output for instance.

Updating query arguments via the Nginx variable

$args

(or

ngx.var.args

in Lua) at runtime is also supported:

ngx.var.args = "a=3&b=42" local args, err = ngx.req.get\_uri\_args()

Here the

args

table will always look like

{a = 3, b = 42}

regardless of the actual request query string.

Note that a maximum of 100 request arguments are parsed by default (including those with the same name) and that additional request arguments are silently discarded to guard against potential denial of service attacks. Since

v0.10.13

, when the limit is exceeded, it will return a second value which is the string

"truncated"

.

However, the optional

max\_args

function argument can be used to override this limit:

local args, err = ngx.req.get\_uri\_args(10) if err == "truncated" then -- one can choose to ignore or reject the current request here end

This argument can be set to zero to remove the limit and to process all request arguments received:

local args, err = ngx.req.get\_uri\_args(0)

Removing the

max\_args

cap is strongly discouraged.

Back to TOC

ngx.req.get_post_args

syntax: args, err = ngx.req.getpostargs(max_args?)

context: rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*

Returns a Lua table holding all the current request POST query arguments (of the MIME type

application/x-www-form-urlencoded

). Call ngx.req.read_body to read the request body first or turn on the lua_need_request_body directive to avoid errors.

location = /test { content\_by\_lua\_block { ngx.req.read\_body() local args, err = ngx.req.get\_post\_args() if err == "truncated" then -- one can choose to ignore or reject the current request here end if not args then ngx.say("failed to get post args: ", err) return end for key, val in pairs(args) do if type(val) == "table" then ngx.say(key, ": ", table.concat(val, ", ")) else ngx.say(key, ": ", val) end end } }

Then

# Post request with the body 'foo=bar&bar=baz&bar=blah' $ curl --data 'foo=bar&bar=baz&bar=blah' localhost/test

will yield the response body like

foo: bar bar: baz, blah

Multiple occurrences of an argument key will result in a table value holding all of the values for that key in order.

Keys and values will be unescaped according to URI escaping rules.

With the settings above,

# POST request with body 'a%20b=1%61+2' $ curl -d 'a%20b=1%61+2' localhost/test

will yield:

a b: 1a 2

Arguments without the

=<value></value>

parts are treated as boolean arguments.

POST /test

with the request body

foo&bar

will yield:

foo: true bar: true

That is, they will take Lua boolean values

true

. However, they are different from arguments taking empty string values.

POST /test

with request body

foo=&bar=

will return something like

foo: bar:

Empty key arguments are discarded.

POST /test

with body

=hello&=world

will yield empty outputs for instance.

Note that a maximum of 100 request arguments are parsed by default (including those with the same name) and that additional request arguments are silently discarded to guard against potential denial of service attacks. Since

v0.10.13

, when the limit is exceeded, it will return a second value which is the string

"truncated"

.

However, the optional

max\_args

function argument can be used to override this limit:

local args, err = ngx.req.get\_post\_args(10) if err == "truncated" then -- one can choose to ignore or reject the current request here end

This argument can be set to zero to remove the limit and to process all request arguments received:

local args, err = ngx.req.get\_post\_args(0)

Removing the

max\_args

cap is strongly discouraged.

Back to TOC

ngx.req.get_headers

syntax: headers, err = ngx.req.getheaders(maxheaders?, raw?)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*

Returns a Lua table holding all the current request headers.

local h, err = ngx.req.get\_headers() if err == "truncated" then -- one can choose to ignore or reject the current request here end for k, v in pairs(h) do ... end

To read an individual header:

ngx.say("Host: ", ngx.req.get\_headers()["Host"])

Note that the ngx.var.HEADER API call, which uses core $http_HEADER variables, may be more preferable for reading individual request headers.

For multiple instances of request headers such as:

Foo: foo Foo: bar Foo: baz

the value of

ngx.req.get\_headers()["Foo"]

will be a Lua (array) table such as:

{"foo", "bar", "baz"}

Note that a maximum of 100 request headers are parsed by default (including those with the same name) and that additional request headers are silently discarded to guard against potential denial of service attacks. Since

v0.10.13

, when the limit is exceeded, it will return a second value which is the string

"truncated"

.

However, the optional

max\_headers

function argument can be used to override this limit:

local headers, err = ngx.req.get\_headers(10) if err == "truncated" then -- one can choose to ignore or reject the current request here end

This argument can be set to zero to remove the limit and to process all request headers received:

local headers, err = ngx.req.get\_headers(0)

Removing the

max\_headers

cap is strongly discouraged.

Since the

0.6.9

release, all the header names in the Lua table returned are converted to the pure lower-case form by default, unless the

raw

argument is set to

true

(default to

false

).

Also, by default, an

\_\_index

metamethod is added to the resulting Lua table and will normalize the keys to a pure lowercase form with all underscores converted to dashes in case of a lookup miss. For example, if a request header

My-Foo-Header

is present, then the following invocations will all pick up the value of this header correctly:

ngx.say(headers.my\_foo\_header) ngx.say(headers["My-Foo-Header"]) ngx.say(headers["my-foo-header"])

The

\_\_index

metamethod will not be added when the

raw

argument is set to

true

.

Back to TOC

ngx.req.set_header

syntax: ngx.req.setheader(headername, header_value)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*

Set the current request's request header named

header\_name

to value

header\_value

, overriding any existing ones.

The input Lua string

header\_name

and

header\_value

should already be well-formed with the URI encoding. For security considerations, this method will automatically escape " ", """, "(", ")", ",", "/", ":", ";", "?", "<", "=", ">", "?", "@", "[", "]", "", "{", "}", 0x00-0x1F, 0x7F-0xFF in

header\_name

and automatically escape "0x00-0x08, 0x0A-0x0F, 0x7F in

header\_value

.

By default, all the subrequests subsequently initiated by ngx.location.capture and ngx.location.capture_multi will inherit the new header.

Here is an example of setting the

Content-Type

header:

ngx.req.set\_header("Content-Type", "text/css")

The

header\_value

can take an array list of values, for example,

ngx.req.set\_header("Foo", {"a", "abc"})

will produce two new request headers:

Foo: a Foo: abc

and old

Foo

headers will be overridden if there is any.

When the

header\_value

argument is

nil

, the request header will be removed. So

ngx.req.set\_header("X-Foo", nil)

is equivalent to

ngx.req.clear\_header("X-Foo")

Note: this function throws a Lua error if

header\_name

or

header\_value

contain unsafe characters (control characters).

Back to TOC

ngx.req.clear_header

syntax: ngx.req.clearheader(headername)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*

Clears the current request's request header named

header\_name

. None of the current request's existing subrequests will be affected but subsequently initiated subrequests will inherit the change by default.

Back to TOC

ngx.req.read_body

syntax: ngx.req.read_body()

context: rewritebylua*, accessbylua*, contentbylua*

Reads the client request body synchronously without blocking the Nginx event loop.

ngx.req.read\_body() local args = ngx.req.get\_post\_args()

If the request body is already read previously by turning on lua_need_request_body or by using other modules, then this function does not run and returns immediately.

If the request body has already been explicitly discarded, either by the ngx.req.discard_body function or other modules, this function does not run and returns immediately.

In case of errors, such as connection errors while reading the data, this method will throw out a Lua exception or terminate the current request with a 500 status code immediately.

The request body data read using this function can be retrieved later via ngx.req.get_body_data or, alternatively, the temporary file name for the body data cached to disk using ngx.req.get_body_file. This depends on

  1. whether the current request body is already larger than the client_body_buffer_size,
  2. and whether client_body_in_file_only has been switched on.

In cases where current request may have a request body and the request body data is not required, The ngx.req.discard_body function must be used to explicitly discard the request body to avoid breaking things under HTTP 1.1 keepalive or HTTP 1.1 pipelining.

This function was first introduced in the

v0.3.1rc17

release.

Back to TOC

ngx.req.discard_body

syntax: ngx.req.discard_body()

context: rewritebylua*, accessbylua*, contentbylua*

Explicitly discard the request body, i.e., read the data on the connection and throw it away immediately (without using the request body by any means).

This function is an asynchronous call and returns immediately.

If the request body has already been read, this function does nothing and returns immediately.

This function was first introduced in the

v0.3.1rc17

release.

See also ngx.req.read_body.

Back to TOC

ngx.req.get_body_data

syntax: data = ngx.req.getbodydata()

context: rewritebylua*, accessbylua*, contentbylua*, logbylua*

Retrieves in-memory request body data. It returns a Lua string rather than a Lua table holding all the parsed query arguments. Use the ngx.req.get_post_args function instead if a Lua table is required.

This function returns

nil

if

  1. the request body has not been read,
  2. the request body has been read into disk temporary files,
  3. or the request body has zero size.

If the request body has not been read yet, call ngx.req.read_body first (or turn on lua_need_request_body to force this module to read the request body. This is not recommended however).

If the request body has been read into disk files, try calling the ngx.req.get_body_file function instead.

To force in-memory request bodies, try setting client_body_buffer_size to the same size value in client_max_body_size.

Note that calling this function instead of using

ngx.var.request\_body

or

ngx.var.echo\_request\_body

is more efficient because it can save one dynamic memory allocation and one data copy.

This function was first introduced in the

v0.3.1rc17

release.

See also ngx.req.get_body_file.

Back to TOC

ngx.req.get_body_file

syntax: filename = ngx.req.getbody_file()

context: rewritebylua*, accessbylua*, contentbylua*

Retrieves the file name for the in-file request body data. Returns

nil

if the request body has not been read or has been read into memory.

The returned file is read only and is usually cleaned up by Nginx's memory pool. It should not be manually modified, renamed, or removed in Lua code.

If the request body has not been read yet, call ngx.req.read_body first (or turn on lua_need_request_body to force this module to read the request body. This is not recommended however).

If the request body has been read into memory, try calling the ngx.req.get_body_data function instead.

To force in-file request bodies, try turning on client_body_in_file_only.

This function was first introduced in the

v0.3.1rc17

release.

See also ngx.req.get_body_data.

Back to TOC

ngx.req.set_body_data

syntax: ngx.req.setbodydata(data)

context: rewritebylua*, accessbylua*, contentbylua*

Set the current request's request body using the in-memory data specified by the

data

argument.

If the request body has not been read yet, call ngx.req.read_body first (or turn on lua_need_request_body to force this module to read the request body. This is not recommended however). Additionally, the request body must not have been previously discarded by ngx.req.discard_body.

Whether the previous request body has been read into memory or buffered into a disk file, it will be freed or the disk file will be cleaned up immediately, respectively.

This function was first introduced in the

v0.3.1rc18

release.

See also ngx.req.set_body_file.

Back to TOC

ngx.req.set_body_file

syntax: ngx.req.setbodyfile(filename, autoclean?)

context: rewritebylua*, accessbylua*, contentbylua*

Set the current request's request body using the in-file data specified by the

file\_name

argument.

If the request body has not been read yet, call ngx.req.read_body first (or turn on lua_need_request_body to force this module to read the request body. This is not recommended however). Additionally, the request body must not have been previously discarded by ngx.req.discard_body.

If the optional

auto\_clean

argument is given a

true

value, then this file will be removed at request completion or the next time this function or ngx.req.set_body_data are called in the same request. The

auto\_clean

is default to

false

.

Please ensure that the file specified by the

file\_name

argument exists and is readable by an Nginx worker process by setting its permission properly to avoid Lua exception errors.

Whether the previous request body has been read into memory or buffered into a disk file, it will be freed or the disk file will be cleaned up immediately, respectively.

This function was first introduced in the

v0.3.1rc18

release.

See also ngx.req.set_body_data.

Back to TOC

ngx.req.init_body

syntax: ngx.req.initbody(buffersize?)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*

Creates a new blank request body for the current request and inializes the buffer for later request body data writing via the ngx.req.append_body and ngx.req.finish_body APIs.

If the

buffer\_size

argument is specified, then its value will be used for the size of the memory buffer for body writing with ngx.req.append_body. If the argument is omitted, then the value specified by the standard client_body_buffer_size directive will be used instead.

When the data can no longer be hold in the memory buffer for the request body, then the data will be flushed onto a temporary file just like the standard request body reader in the Nginx core.

It is important to always call the ngx.req.finish_body after all the data has been appended onto the current request body. Also, when this function is used together with ngx.req.socket, it is required to call ngx.req.socket before this function, or you will get the "request body already exists" error message.

The usage of this function is often like this:

ngx.req.init\_body(128 \* 1024) -- buffer is 128KB for chunk in next\_data\_chunk() do ngx.req.append\_body(chunk) -- each chunk can be 4KB end ngx.req.finish\_body()

This function can be used with ngx.req.append_body, ngx.req.finish_body, and ngx.req.socket to implement efficient input filters in pure Lua (in the context of rewrite_by_lua* or access_by_lua*), which can be used with other Nginx content handler or upstream modules like ngx_http_proxy_module and ngx_http_fastcgi_module.

This function was first introduced in the

v0.5.11

release.

Back to TOC

ngx.req.append_body

syntax: ngx.req.appendbody(datachunk)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*

Append new data chunk specified by the

data\_chunk

argument onto the existing request body created by the ngx.req.init_body call.

When the data can no longer be hold in the memory buffer for the request body, then the data will be flushed onto a temporary file just like the standard request body reader in the Nginx core.

It is important to always call the ngx.req.finish_body after all the data has been appended onto the current request body.

This function can be used with ngx.req.init_body, ngx.req.finish_body, and ngx.req.socket to implement efficient input filters in pure Lua (in the context of rewrite_by_lua* or access_by_lua*), which can be used with other Nginx content handler or upstream modules like ngx_http_proxy_module and ngx_http_fastcgi_module.

This function was first introduced in the

v0.5.11

release.

See also ngx.req.init_body.

Back to TOC

ngx.req.finish_body

syntax: ngx.req.finish_body()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*

Completes the construction process of the new request body created by the ngx.req.init_body and ngx.req.append_body calls.

This function can be used with ngx.req.init_body, ngx.req.append_body, and ngx.req.socket to implement efficient input filters in pure Lua (in the context of rewrite_by_lua* or access_by_lua*), which can be used with other Nginx content handler or upstream modules like ngx_http_proxy_module and ngx_http_fastcgi_module.

This function was first introduced in the

v0.5.11

release.

See also ngx.req.init_body.

Back to TOC

ngx.req.socket

syntax: tcpsock, err = ngx.req.socket()

syntax: tcpsock, err = ngx.req.socket(raw)

context: rewritebylua*, accessbylua*, contentbylua*

Returns a read-only cosocket object that wraps the downstream connection. Only receive, receiveany and receiveuntil methods are supported on this object.

In case of error,

nil

will be returned as well as a string describing the error.

The socket object returned by this method is usually used to read the current request's body in a streaming fashion. Do not turn on the lua_need_request_body directive, and do not mix this call with ngx.req.read_body and ngx.req.discard_body.

If any request body data has been pre-read into the Nginx core request header buffer, the resulting cosocket object will take care of this to avoid potential data loss resulting from such pre-reading. Chunked request bodies are not yet supported in this API.

Since the

v0.9.0

release, this function accepts an optional boolean

raw

argument. When this argument is

true

, this function returns a full-duplex cosocket object wrapping around the raw downstream connection socket, upon which you can call the receive, receiveany, receiveuntil, and send methods.

When the

raw

argument is

true

, it is required that no pending data from any previous ngx.say, ngx.print, or ngx.send_headers calls exists. So if you have these downstream output calls previously, you should call ngx.flush(true) before calling

ngx.req.socket(true)

to ensure that there is no pending output data. If the request body has not been read yet, then this "raw socket" can also be used to read the request body.

You can use the "raw request socket" returned by

ngx.req.socket(true)

to implement fancy protocols like WebSocket, or just emit your own raw HTTP response header or body data. You can refer to the lua-resty-websocket library for a real world example.

This function was first introduced in the

v0.5.0rc1

release.

Back to TOC

ngx.exec

syntax: ngx.exec(uri, args?)

context: rewritebylua*, accessbylua*, contentbylua*

Does an internal redirect to

uri

with

args

and is similar to the echo_exec directive of the echo-nginx-module.

ngx.exec('/some-location'); ngx.exec('/some-location', 'a=3&b=5&c=6'); ngx.exec('/some-location?a=3&b=5', 'c=6');

The optional second

args

can be used to specify extra URI query arguments, for example:

ngx.exec("/foo", "a=3&b=hello%20world")

Alternatively, a Lua table can be passed for the

args

argument for ngx_lua to carry out URI escaping and string concatenation.

ngx.exec("/foo", { a = 3, b = "hello world" })

The result is exactly the same as the previous example.

The format for the Lua table passed as the

args

argument is identical to the format used in the ngx.encode_args method.

Named locations are also supported but the second

args

argument will be ignored if present and the querystring for the new target is inherited from the referring location (if any).

GET /foo/file.php?a=hello

will return "hello" and not "goodbye" in the example below

location /foo { content\_by\_lua\_block { ngx.exec("@bar", "a=goodbye"); } } location @bar { content\_by\_lua\_block { local args = ngx.req.get\_uri\_args() for key, val in pairs(args) do if key == "a" then ngx.say(val) end end } }

Note that the

ngx.exec

method is different from ngx.redirect in that it is purely an internal redirect and that no new external HTTP traffic is involved.

Also note that this method call terminates the processing of the current request and that it must be called before ngx.send_headers or explicit response body outputs by either ngx.print or ngx.say.

It is recommended that a coding style that combines this method call with the

return

statement, i.e.,

return ngx.exec(...)

be adopted when this method call is used in contexts other than header_filter_by_lua* to reinforce the fact that the request processing is being terminated.

Back to TOC

ngx.redirect

syntax: ngx.redirect(uri, status?)

context: rewritebylua*, accessbylua*, contentbylua*

Issue an

HTTP 301

or

302

redirection to

uri

.

Note: this function throws a Lua error if the

uri

argument contains unsafe characters (control characters).

The optional

status

parameter specifies the HTTP status code to be used. The following status codes are supported right now:

301
  • 302
    (default)
  • 303
  • 307
  • 308

It is

302

(

ngx.HTTP\_MOVED\_TEMPORARILY

) by default.

Here is an example assuming the current server name is

localhost

and that it is listening on port 1984:

return ngx.redirect("/foo")

which is equivalent to

return ngx.redirect("/foo", ngx.HTTP\_MOVED\_TEMPORARILY)

Redirecting arbitrary external URLs is also supported, for example:

return ngx.redirect("http://www.google.com")

We can also use the numerical code directly as the second

status

argument:

return ngx.redirect("/foo", 301)

This method is similar to the rewrite directive with the

redirect

modifier in the standardngx_http_rewrite_module, for example, this

nginx.conf

snippet

rewrite ^ /foo? redirect; # nginx config

is equivalent to the following Lua code

return ngx.redirect('/foo'); -- Lua code

while

rewrite ^ /foo? permanent; # nginx config

is equivalent to

return ngx.redirect('/foo', ngx.HTTP\_MOVED\_PERMANENTLY) -- Lua code

URI arguments can be specified as well, for example:

return ngx.redirect('/foo?a=3&b=4')

Note that this method call terminates the processing of the current request and that it must be called before ngx.send_headers or explicit response body outputs by either ngx.print or ngx.say.

It is recommended that a coding style that combines this method call with the

return

statement, i.e.,

return ngx.redirect(...)

be adopted when this method call is used in contexts other than header_filter_by_lua* to reinforce the fact that the request processing is being terminated.

Back to TOC

ngx.send_headers

syntax: ok, err = ngx.send_headers()

context: rewritebylua*, accessbylua*, contentbylua*

Explicitly send out the response headers.

Since

v0.8.3

this function returns

1

on success, or returns

nil

and a string describing the error otherwise.

Note that there is normally no need to manually send out response headers as ngx_lua will automatically send headers out before content is output with ngx.say or ngx.print or when content_by_lua* exits normally.

Back to TOC

ngx.headers_sent

syntax: value = ngx.headers_sent

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*

Returns

true

if the response headers have been sent (by ngx_lua), and

false

otherwise.

This API was first introduced in ngx_lua v0.3.1rc6.

Back to TOC

ngx.print

syntax: ok, err = ngx.print(...)

context: rewritebylua*, accessbylua*, contentbylua*

Emits arguments concatenated to the HTTP client (as response body). If response headers have not been sent, this function will send headers out first and then output body data.

Since

v0.8.3

this function returns

1

on success, or returns

nil

and a string describing the error otherwise.

Lua

nil

values will output

"nil"

strings and Lua boolean values will output

"true"

and

"false"

literal strings respectively.

Nested arrays of strings are permitted and the elements in the arrays will be sent one by one:

local table = { "hello, ", {"world: ", true, " or ", false, {": ", nil}} } ngx.print(table)

will yield the output

hello, world: true or false: nil

Non-array table arguments will cause a Lua exception to be thrown.

The

ngx.null

constant will yield the

"null"

string output.

This is an asynchronous call and will return immediately without waiting for all the data to be written into the system send buffer. To run in synchronous mode, call

ngx.flush(true)

after calling

ngx.print

. This can be particularly useful for streaming output. See ngx.flush for more details.

Please note that both

ngx.print

and ngx.say will always invoke the whole Nginx output body filter chain, which is an expensive operation. So be careful when calling either of these two in a tight loop; buffer the data yourself in Lua and save the calls.

Back to TOC

ngx.say

syntax: ok, err = ngx.say(...)

context: rewritebylua*, accessbylua*, contentbylua*

Just as ngx.print but also emit a trailing newline.

Back to TOC

ngx.log

syntax: ngx.log(log_level, ...)

context: initbylua*, initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Log arguments concatenated to error.log with the given logging level.

Lua

nil

arguments are accepted and result in literal

"nil"

string while Lua booleans result in literal

"true"

or

"false"

string outputs. And the

ngx.null

constant will yield the

"null"

string output.

The

log\_level

argument can take constants like

ngx.ERR

and

ngx.WARN

. Check out Nginx log level constants for details.

There is a hard coded

2048

byte limitation on error message lengths in the Nginx core. This limit includes trailing newlines and leading time stamps. If the message size exceeds this limit, Nginx will truncate the message text accordingly. This limit can be manually modified by editing the

NGX\_MAX\_ERROR\_STR

macro definition in the

src/core/ngx\_log.h

file in the Nginx source tree.

Back to TOC

ngx.flush

syntax: ok, err = ngx.flush(wait?)

context: rewritebylua*, accessbylua*, contentbylua*

Flushes response output to the client.

ngx.flush

accepts an optional boolean

wait

argument (Default:

false

) first introduced in the

v0.3.1rc34

release. When called with the default argument, it issues an asynchronous call (Returns immediately without waiting for output data to be written into the system send buffer). Calling the function with the

wait

argument set to

true

switches to synchronous mode.

In synchronous mode, the function will not return until all output data has been written into the system send buffer or until the send_timeout setting has expired. Note that using the Lua coroutine mechanism means that this function does not block the Nginx event loop even in the synchronous mode.

When

ngx.flush(true)

is called immediately after ngx.print or ngx.say, it causes the latter functions to run in synchronous mode. This can be particularly useful for streaming output.

Note that

ngx.flush

is not functional when in the HTTP 1.0 output buffering mode. See HTTP 1.0 support.

Since

v0.8.3

this function returns

1

on success, or returns

nil

and a string describing the error otherwise.

Back to TOC

ngx.exit

syntax: ngx.exit(status)

context: rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

When

status \>= 200

(i.e.,

ngx.HTTP\_OK

and above), it will interrupt the execution of the current request and return status code to Nginx.

When

status == 0

(i.e.,

ngx.OK

), it will only quit the current phase handler (or the content handler if the content_by_lua* directive is used) and continue to run later phases (if any) for the current request.

The

status

argument can be

ngx.OK

,

ngx.ERROR

,

ngx.HTTP\_NOT\_FOUND

,

ngx.HTTP\_MOVED\_TEMPORARILY

, or other HTTP status constants.

To return an error page with custom contents, use code snippets like this:

ngx.status = ngx.HTTP\_GONE ngx.say("This is our own content") -- to cause quit the whole request rather than the current phase handler ngx.exit(ngx.HTTP\_OK)

The effect in action:

$ curl -i http://localhost/test HTTP/1.1 410 Gone Server: nginx/1.0.6 Date: Thu, 15 Sep 2011 00:51:48 GMT Content-Type: text/plain Transfer-Encoding: chunked Connection: keep-alive This is our own content

Number literals can be used directly as the argument, for instance,

ngx.exit(501)

Note that while this method accepts all HTTP status constants as input, it only accepts

ngx.OK

and

ngx.ERROR

of the core constants.

Also note that this method call terminates the processing of the current request and that it is recommended that a coding style that combines this method call with the

return

statement, i.e.,

return ngx.exit(...)

be used to reinforce the fact that the request processing is being terminated.

When being used in the contexts of header_filter_by_lua*, balancer_by_lua*, andssl_session_store_by_lua*,

ngx.exit()

is an asynchronous operation and will return immediately. This behavior may change in future and it is recommended that users always use

return

in combination as suggested above.

Back to TOC

ngx.eof

syntax: ok, err = ngx.eof()

context: rewritebylua*, accessbylua*, contentbylua*

Explicitly specify the end of the response output stream. In the case of HTTP 1.1 chunked encoded output, it will just trigger the Nginx core to send out the "last chunk".

When you disable the HTTP 1.1 keep-alive feature for your downstream connections, you can rely on well written HTTP clients to close the connection actively for you when you call this method. This trick can be used do back-ground jobs without letting the HTTP clients to wait on the connection, as in the following example:

location = /async { keepalive\_timeout 0; content\_by\_lua\_block { ngx.say("got the task!") ngx.eof() -- well written HTTP clients will close the connection at this point -- access MySQL, PostgreSQL, Redis, Memcached, and etc here... } }

But if you create subrequests to access other locations configured by Nginx upstream modules, then you should configure those upstream modules to ignore client connection abortions if they are not by default. For example, by default the standard ngx_http_proxy_module will terminate both the subrequest and the main request as soon as the client closes the connection, so it is important to turn on the proxy_ignore_client_abort directive in your location block configured by ngx_http_proxy_module:

proxy\_ignore\_client\_abort on;

A better way to do background jobs is to use the ngx.timer.at API.

Since

v0.8.3

this function returns

1

on success, or returns

nil

and a string describing the error otherwise.

Back to TOC

ngx.sleep

syntax: ngx.sleep(seconds)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Sleeps for the specified seconds without blocking. One can specify time resolution up to 0.001 seconds (i.e., one millisecond).

Behind the scene, this method makes use of the Nginx timers.

Since the

0.7.20

release, The

0

time argument can also be specified.

This method was introduced in the

0.5.0rc30

release.

Back to TOC

ngx.escape_uri

syntax: newstr = ngx.escape_uri(str, type?)

context: initbylua*, initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Since

v0.10.16

, this function accepts an optional

type

argument. It accepts the following values (defaults to

2

):

0

: escapes

str

as a full URI. And the characters

(space),

#

,

%

,

?

, 0x00 ~ 0x1F, 0x7F ~ 0xFF will be escaped.

2

: escape

str

as a URI component. All characters except alphabetic characters, digits,

-

,

.

,

\_

,

~

will be encoded as

%XX

.

Back to TOC

ngx.unescape_uri

syntax: newstr = ngx.unescape_uri(str)

context: initbylua*, initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*

Unescape

str

as an escaped URI component.

For example,

ngx.say(ngx.unescape\_uri("b%20r56+7"))

gives the output

b r56 7

Back to TOC

ngx.encode_args

syntax: str = ngx.encode_args(table)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificateby_lua*

Encode the Lua table to a query args string according to the URI encoded rules.

For example,

ngx.encode\_args({foo = 3, ["b r"] = "hello world"})

yields

foo=3&b%20r=hello%20world

The table keys must be Lua strings.

Multi-value query args are also supported. Just use a Lua table for the argument's value, for example:

ngx.encode\_args({baz = {32, "hello"}})

gives

baz=32&baz=hello

If the value table is empty and the effect is equivalent to the

nil

value.

Boolean argument values are also supported, for instance,

ngx.encode\_args({a = true, b = 1})

yields

a&b=1

If the argument value is

false

, then the effect is equivalent to the

nil

value.

This method was first introduced in the

v0.3.1rc27

release.

Back to TOC

ngx.decode_args

syntax: table, err = ngx.decodeargs(str, maxargs?)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Decodes a URI encoded query-string into a Lua table. This is the inverse function of ngx.encode_args.

The optional

max\_args

argument can be used to specify the maximum number of arguments parsed from the

str

argument. By default, a maximum of 100 request arguments are parsed (including those with the same name) and that additional URI arguments are silently discarded to guard against potential denial of service attacks. Since

v0.10.13

, when the limit is exceeded, it will return a second value which is the string

"truncated"

.

This argument can be set to zero to remove the limit and to process all request arguments received:

local args = ngx.decode\_args(str, 0)

Removing the

max\_args

cap is strongly discouraged.

This method was introduced in the

v0.5.0rc29

.

Back to TOC

ngx.encode_base64

syntax: newstr = ngx.encodebase64(str, nopadding?)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Encodes

str

to a base64 digest.

Since the

0.9.16

release, an optional boolean-typed

no\_padding

argument can be specified to control whether the base64 padding should be appended to the resulting digest (default to

false

, i.e., with padding enabled).

Back to TOC

ngx.decode_base64

syntax: newstr = ngx.decode_base64(str)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Decodes the

str

argument as a base64 digest to the raw form. Returns

nil

if

str

is not well formed.

Back to TOC

ngx.crc32_short

syntax: intval = ngx.crc32_short(str)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Calculates the CRC-32 (Cyclic Redundancy Code) digest for the

str

argument.

This method performs better on relatively short

str

inputs (i.e., less than 30 ~ 60 bytes), as compared to ngx.crc32_long. The result is exactly the same as ngx.crc32_long.

Behind the scene, it is just a thin wrapper around the

ngx\_crc32\_short

function defined in the Nginx core.

This API was first introduced in the

v0.3.1rc8

release.

Back to TOC

ngx.crc32_long

syntax: intval = ngx.crc32_long(str)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Calculates the CRC-32 (Cyclic Redundancy Code) digest for the

str

argument.

This method performs better on relatively long

str

inputs (i.e., longer than 30 ~ 60 bytes), as compared to ngx.crc32_short. The result is exactly the same as ngx.crc32_short.

Behind the scene, it is just a thin wrapper around the

ngx\_crc32\_long

function defined in the Nginx core.

This API was first introduced in the

v0.3.1rc8

release.

Back to TOC

ngx.hmac_sha1

syntax: digest = ngx.hmacsha1(secretkey, str)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Computes the HMAC-SHA1 digest of the argument

str

and turns the result using the secret key

<secret_key></secret_key>

.

The raw binary form of the

HMAC-SHA1

digest will be generated, use ngx.encode_base64, for example, to encode the result to a textual representation if desired.

For example,

local key = "thisisverysecretstuff" local src = "some string we want to sign" local digest = ngx.hmac\_sha1(key, src) ngx.say(ngx.encode\_base64(digest))

yields the output

R/pvxzHC4NLtj7S+kXFg/NePTmk=

This API requires the OpenSSL library enabled in the Nginx build (usually by passing the

--with-http\_ssl\_module

option to the

./configure

script).

This function was first introduced in the

v0.3.1rc29

release.

Back to TOC

ngx.md5

syntax: digest = ngx.md5(str)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Returns the hexadecimal representation of the MD5 digest of the

str

argument.

For example,

location = /md5 { content\_by\_lua\_block { ngx.say(ngx.md5("hello")) } }

yields the output

5d41402abc4b2a76b9719d911017c592

See ngx.md5_bin if the raw binary MD5 digest is required.

Back to TOC

ngx.md5_bin

syntax: digest = ngx.md5_bin(str)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Returns the binary form of the MD5 digest of the

str

argument.

See ngx.md5 if the hexadecimal form of the MD5 digest is required.

Back to TOC

ngx.sha1_bin

syntax: digest = ngx.sha1_bin(str)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Returns the binary form of the SHA-1 digest of the

str

argument.

This function requires SHA-1 support in the Nginx build. (This usually just means OpenSSL should be installed while building Nginx).

This function was first introduced in the

v0.5.0rc6

.

Back to TOC

ngx.quote_sql_str

syntax: quotedvalue = ngx.quotesqlstr(rawvalue)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Returns a quoted SQL string literal according to the MySQL quoting rules.

Back to TOC

ngx.today

syntax: str = ngx.today()

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Returns current date (in the format

yyyy-mm-dd

) from the Nginx cached time (no syscall involved unlike Lua's date library).

This is the local time.

Back to TOC

ngx.time

syntax: secs = ngx.time()

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Returns the elapsed seconds from the epoch for the current time stamp from the Nginx cached time (no syscall involved unlike Lua's date library).

Updates of the Nginx time cache can be forced by calling ngx.update_time first.

Back to TOC

ngx.now

syntax: secs = ngx.now()

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Returns a floating-point number for the elapsed time in seconds (including milliseconds as the decimal part) from the epoch for the current time stamp from the Nginx cached time (no syscall involved unlike Lua's date library).

You can forcibly update the Nginx time cache by calling ngx.update_time first.

This API was first introduced in

v0.3.1rc32

.

Back to TOC

ngx.update_time

syntax: ngx.update_time()

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Forcibly updates the Nginx current time cache. This call involves a syscall and thus has some overhead, so do not abuse it.

This API was first introduced in

v0.3.1rc32

.

Back to TOC

ngx.localtime

syntax: str = ngx.localtime()

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Returns the current time stamp (in the format

yyyy-mm-dd hh:mm:ss

) of the Nginx cached time (no syscall involved unlike Lua's os.date function).

This is the local time.

Back to TOC

ngx.utctime

syntax: str = ngx.utctime()

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Returns the current time stamp (in the format

yyyy-mm-dd hh:mm:ss

) of the Nginx cached time (no syscall involved unlike Lua's os.date function).

This is the UTC time.

Back to TOC

ngx.cookie_time

syntax: str = ngx.cookie_time(sec)

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Returns a formatted string can be used as the cookie expiration time. The parameter

sec

is the time stamp in seconds (like those returned from ngx.time).

ngx.say(ngx.cookie\_time(1290079655)) -- yields "Thu, 18-Nov-10 11:27:35 GMT"

Back to TOC

ngx.http_time

syntax: str = ngx.http_time(sec)

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Returns a formated string can be used as the http header time (for example, being used in

Last-Modified

header). The parameter

sec

is the time stamp in seconds (like those returned from ngx.time).

ngx.say(ngx.http\_time(1290079655)) -- yields "Thu, 18 Nov 2010 11:27:35 GMT"

Back to TOC

ngx.parse_http_time

syntax: sec = ngx.parsehttptime(str)

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Parse the http time string (as returned by ngx.http_time) into seconds. Returns the seconds or

nil

if the input string is in bad forms.

local time = ngx.parse\_http\_time("Thu, 18 Nov 2010 11:27:35 GMT") if time == nil then ... end

Back to TOC

ngx.is_subrequest

syntax: value = ngx.is_subrequest

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*

Returns

true

if the current request is an Nginx subrequest, or

false

otherwise.

Back to TOC

ngx.re.match

syntax: captures, err = ngx.re.match(subject, regex, options?, ctx?, res_table?)

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Matches the

subject

string using the Perl compatible regular expression

regex

with the optional

options

.

Only the first occurrence of the match is returned, or

nil

if no match is found. In case of errors, like seeing a bad regular expression or exceeding the PCRE stack limit,

nil

and a string describing the error will be returned.

When a match is found, a Lua table

captures

is returned, where

captures[0]

holds the whole substring being matched, and

captures[1]

holds the first parenthesized sub-pattern's capturing,

captures[2]

the second, and so on.

local m, err = ngx.re.match("hello, 1234", "[0-9]+") if m then -- m[0] == "1234" else if err then ngx.log(ngx.ERR, "error: ", err) return end ngx.say("match not found") end
local m, err = ngx.re.match("hello, 1234", "([0-9])[0-9]+") -- m[0] == "1234" -- m[1] == "1"

Named captures are also supported since the

v0.7.14

release and are returned in the same Lua table as key-value pairs as the numbered captures.

local m, err = ngx.re.match("hello, 1234", "([0-9])(?<remaining>[0-9]+)")
 -- m[0] == "1234"
 -- m[1] == "1"
 -- m[2] == "234"
 -- m["remaining"] == "234"
</remaining>

Unmatched subpatterns will have

false

values in their

captures

table fields.

local m, err = ngx.re.match("hello, world", "(world)|(hello)|(?<named>howdy)")
 -- m[0] == "hello"
 -- m[1] == false
 -- m[2] == "hello"
 -- m[3] == false
 -- m["named"] == false
</named>

Specify

options

to control how the match operation will be performed. The following option characters are supported:

a anchored mode (only match from the beginning) d enable the DFA mode (or the longest token match semantics). this requires PCRE 6.0+ or else a Lua exception will be thrown. first introduced in ngx\_lua v0.3.1rc30. D enable duplicate named pattern support. This allows named subpattern names to be repeated, returning the captures in an array-like Lua table. for example, local m = ngx.re.match("hello, world", "(?<named>\w+), (?<named>\w+)",
                                       "D")
                -- m["named"] == {"hello", "world"}
              this option was first introduced in the v0.7.14 release.
              this option requires at least PCRE 8.12.

i case insensitive mode (similar to Perl's /i modifier)

j enable PCRE JIT compilation, this requires PCRE 8.21+ which
              must be built with the --enable-jit option. for optimum performance,
              this option should always be used together with the 'o' option.
              first introduced in ngx_lua v0.3.1rc30.

J enable the PCRE Javascript compatible mode. this option was
              first introduced in the v0.7.14 release. this option requires
              at least PCRE 8.12.

m multi-line mode (similar to Perl's /m modifier)

o compile-once mode (similar to Perl's /o modifier),
              to enable the worker-process-level compiled-regex cache

s single-line mode (similar to Perl's /s modifier)

u UTF-8 mode. this requires PCRE to be built with
              the --enable-utf8 option or else a Lua exception will be thrown.

U similar to "u" but disables PCRE's UTF-8 validity check on
              the subject string. first introduced in ngx_lua v0.8.1.

x extended mode (similar to Perl's /x modifier)
</named></named>

These options can be combined:

local m, err = ngx.re.match("hello, world", "HEL LO", "ix") -- m[0] == "hello"
local m, err = ngx.re.match("hello, 美好生活", "HELLO, (.{2})", "iu") -- m[0] == "hello, 美好" -- m[1] == "美好"

The

o

option is useful for performance tuning, because the regex pattern in question will only be compiled once, cached in the worker-process level, and shared among all requests in the current Nginx worker process. The upper limit of the regex cache can be tuned via the lua_regex_cache_max_entries directive.

The optional fourth argument,

ctx

, can be a Lua table holding an optional

pos

field. When the

pos

field in the

ctx

table argument is specified,

ngx.re.match

will start matching from that offset (starting from 1). Regardless of the presence of the

pos

field in the

ctx

table,

ngx.re.match

will always set this

pos

field to the position after the substring matched by the whole pattern in case of a successful match. When match fails, the

ctx

table will be left intact.

local ctx = {} local m, err = ngx.re.match("1234, hello", "[0-9]+", "", ctx) -- m[0] = "1234" -- ctx.pos == 5
local ctx = { pos = 2 } local m, err = ngx.re.match("1234, hello", "[0-9]+", "", ctx) -- m[0] = "234" -- ctx.pos == 5

The

ctx

table argument combined with the

a

regex modifier can be used to construct a lexer atop

ngx.re.match

.

Note that, the

options

argument is not optional when the

ctx

argument is specified and that the empty Lua string (

""

) must be used as placeholder for

options

if no meaningful regex options are required.

This method requires the PCRE library enabled in Nginx (Known Issue With Special Escaping Sequences).

To confirm that PCRE JIT is enabled, activate the Nginx debug log by adding the

--with-debug

option to Nginx or OpenResty's

./configure

script. Then, enable the "debug" error log level in

error\_log

directive. The following message will be generated if PCRE JIT is enabled:

pcre JIT compiling result: 1

Starting from the

0.9.4

release, this function also accepts a 5th argument,

res\_table

, for letting the caller supply the Lua table used to hold all the capturing results. Starting from

0.9.6

, it is the caller's responsibility to ensure this table is empty. This is very useful for recycling Lua tables and saving GC and table allocation overhead.

This feature was introduced in the

v0.2.1rc11

release.

Back to TOC

ngx.re.find

syntax: from, to, err = ngx.re.find(subject, regex, options?, ctx?, nth?)

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Similar to ngx.re.match but only returns the beginning index (

from

) and end index (

to

) of the matched substring. The returned indexes are 1-based and can be fed directly into the string.sub API function to obtain the matched substring.

In case of errors (like bad regexes or any PCRE runtime errors), this API function returns two

nil

values followed by a string describing the error.

If no match is found, this function just returns a

nil

value.

Below is an example:

local s = "hello, 1234" local from, to, err = ngx.re.find(s, "([0-9]+)", "jo") if from then ngx.say("from: ", from) ngx.say("to: ", to) ngx.say("matched: ", string.sub(s, from, to)) else if err then ngx.say("error: ", err) return end ngx.say("not matched!") end

This example produces the output

from: 8 to: 11 matched: 1234

Because this API function does not create new Lua strings nor new Lua tables, it is much faster than ngx.re.match. It should be used wherever possible.

Since the

0.9.3

release, an optional 5th argument,

nth

, is supported to specify which (submatch) capture's indexes to return. When

nth

is 0 (which is the default), the indexes for the whole matched substring is returned; when

nth

is 1, then the 1st submatch capture's indexes are returned; when

nth

is 2, then the 2nd submatch capture is returned, and so on. When the specified submatch does not have a match, then two

nil

values will be returned. Below is an example for this:

local str = "hello, 1234" local from, to = ngx.re.find(str, "([0-9])([0-9]+)", "jo", nil, 2) if from then ngx.say("matched 2nd submatch: ", string.sub(str, from, to)) -- yields "234" end

This API function was first introduced in the

v0.9.2

release.

Back to TOC

ngx.re.gmatch

syntax: iterator, err = ngx.re.gmatch(subject, regex, options?)

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Similar to ngx.re.match, but returns a Lua iterator instead, so as to let the user programmer iterate all the matches over the

<subject></subject>

string argument with the PCRE

regex

.

In case of errors, like seeing an ill-formed regular expression,

nil

and a string describing the error will be returned.

Here is a small example to demonstrate its basic usage:

local iterator, err = ngx.re.gmatch("hello, world!", "([a-z]+)", "i") if not iterator then ngx.log(ngx.ERR, "error: ", err) return end local m m, err = iterator() -- m[0] == m[1] == "hello" if err then ngx.log(ngx.ERR, "error: ", err) return end m, err = iterator() -- m[0] == m[1] == "world" if err then ngx.log(ngx.ERR, "error: ", err) return end m, err = iterator() -- m == nil if err then ngx.log(ngx.ERR, "error: ", err) return end

More often we just put it into a Lua loop:

local it, err = ngx.re.gmatch("hello, world!", "([a-z]+)", "i") if not it then ngx.log(ngx.ERR, "error: ", err) return end while true do local m, err = it() if err then ngx.log(ngx.ERR, "error: ", err) return end if not m then -- no match found (any more) break end -- found a match ngx.say(m[0]) ngx.say(m[1]) end

The optional

options

argument takes exactly the same semantics as the ngx.re.match method.

The current implementation requires that the iterator returned should only be used in a single request. That is, one should not assign it to a variable belonging to persistent namespace like a Lua package.

This method requires the PCRE library enabled in Nginx (Known Issue With Special Escaping Sequences).

This feature was first introduced in the

v0.2.1rc12

release.

Back to TOC

ngx.re.sub

syntax: newstr, n, err = ngx.re.sub(subject, regex, replace, options?)

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Substitutes the first match of the Perl compatible regular expression

regex

on the

subject

argument string with the string or function argument

replace

. The optional

options

argument has exactly the same meaning as in ngx.re.match.

This method returns the resulting new string as well as the number of successful substitutions. In case of failures, like syntax errors in the regular expressions or the

<replace></replace>

string argument, it will return

nil

and a string describing the error.

When the

replace

is a string, then it is treated as a special template for string replacement. For example,

local newstr, n, err = ngx.re.sub("hello, 1234", "([0-9])[0-9]", "[$0][$1]") if not newstr then ngx.log(ngx.ERR, "error: ", err) return end -- newstr == "hello, [12][1]34" -- n == 1

where

$0

referring to the whole substring matched by the pattern and

$1

referring to the first parenthesized capturing substring.

Curly braces can also be used to disambiguate variable names from the background string literals:

local newstr, n, err = ngx.re.sub("hello, 1234", "[0-9]", "${0}00") -- newstr == "hello, 100234" -- n == 1

Literal dollar sign characters (

$

) in the

replace

string argument can be escaped by another dollar sign, for instance,

local newstr, n, err = ngx.re.sub("hello, 1234", "[0-9]", "$$") -- newstr == "hello, $234" -- n == 1

Do not use backlashes to escape dollar signs; it will not work as expected.

When the

replace

argument is of type "function", then it will be invoked with the "match table" as the argument to generate the replace string literal for substitution. The "match table" fed into the

replace

function is exactly the same as the return value of ngx.re.match. Here is an example:

local func = function (m) return "[" .. m[0] .. "][" .. m[1] .. "]" end local newstr, n, err = ngx.re.sub("hello, 1234", "( [0-9] ) [0-9]", func, "x") -- newstr == "hello, [12][1]34" -- n == 1

The dollar sign characters in the return value of the

replace

function argument are not special at all.

This method requires the PCRE library enabled in Nginx (Known Issue With Special Escaping Sequences).

This feature was first introduced in the

v0.2.1rc13

release.

Back to TOC

ngx.re.gsub

syntax: newstr, n, err = ngx.re.gsub(subject, regex, replace, options?)

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Just like ngx.re.sub, but does global substitution.

Here is some examples:

local newstr, n, err = ngx.re.gsub("hello, world", "([a-z])[a-z]+", "[$0,$1]", "i") if not newstr then ngx.log(ngx.ERR, "error: ", err) return end -- newstr == "[hello,h], [world,w]" -- n == 2
local func = function (m) return "[" .. m[0] .. "," .. m[1] .. "]" end local newstr, n, err = ngx.re.gsub("hello, world", "([a-z])[a-z]+", func, "i") -- newstr == "[hello,h], [world,w]" -- n == 2

This method requires the PCRE library enabled in Nginx (Known Issue With Special Escaping Sequences).

This feature was first introduced in the

v0.2.1rc15

release.

Back to TOC

ngx.shared.DICT

syntax: dict = ngx.shared.DICT

syntax: dict = ngx.shared[name_var]

context: initbylua*, initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Fetching the shm-based Lua dictionary object for the shared memory zone named

DICT

defined by the lua_shared_dict directive.

Shared memory zones are always shared by all the Nginx worker processes in the current Nginx server instance.

The resulting object

dict

has the following methods:

All these methods are atomic operations, that is, safe from concurrent accesses from multiple Nginx worker processes for the same

lua\_shared\_dict

zone.

Here is an example:

http { lua\_shared\_dict dogs 10m; server { location /set { content\_by\_lua\_block { local dogs = ngx.shared.dogs dogs:set("Jim", 8) ngx.say("STORED") } } location /get { content\_by\_lua\_block { local dogs = ngx.shared.dogs ngx.say(dogs:get("Jim")) } } } }

Let us test it:

$ curl localhost/set STORED $ curl localhost/get 8 $ curl localhost/get 8

The number

8

will be consistently output when accessing

/get

regardless of how many Nginx workers there are because the

dogs

dictionary resides in the shared memory and visible to all of the worker processes.

The shared dictionary will retain its contents through a server config reload (either by sending the

HUP

signal to the Nginx process or by using the

-s reload

command-line option).

The contents in the dictionary storage will be lost, however, when the Nginx server quits.

This feature was first introduced in the

v0.3.1rc22

release.

Back to TOC

ngx.shared.DICT.get

syntax: value, flags = ngx.shared.DICT:get(key)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Retrieving the value in the dictionary ngx.shared.DICT for the key

key

. If the key does not exist or has expired, then

nil

will be returned.

In case of errors,

nil

and a string describing the error will be returned.

The value returned will have the original data type when they were inserted into the dictionary, for example, Lua booleans, numbers, or strings.

The first argument to this method must be the dictionary object itself, for example,

local cats = ngx.shared.cats local value, flags = cats.get(cats, "Marry")

or use Lua's syntactic sugar for method calls:

local cats = ngx.shared.cats local value, flags = cats:get("Marry")

These two forms are fundamentally equivalent.

If the user flags is

0

(the default), then no flags value will be returned.

This feature was first introduced in the

v0.3.1rc22

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.get_stale

syntax: value, flags, stale = ngx.shared.DICT:get_stale(key)

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Similar to the get method but returns the value even if the key has already expired.

Returns a 3rd value,

stale

, indicating whether the key has expired or not.

Note that the value of an expired key is not guaranteed to be available so one should never rely on the availability of expired items.

This method was first introduced in the

0.8.6

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.set

syntax: success, err, forcible = ngx.shared.DICT:set(key, value, exptime?, flags?)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Unconditionally sets a key-value pair into the shm-based dictionary ngx.shared.DICT. Returns three values:

  • success
    : boolean value to indicate whether the key-value pair is stored or not.
  • err
    : textual error message, can be
    "no memory"
    .
  • forcible
    : a boolean value to indicate whether other valid items have been removed forcibly when out of storage in the shared memory zone.

The

value

argument inserted can be Lua booleans, numbers, strings, or

nil

. Their value type will also be stored into the dictionary and the same data type can be retrieved later via the get method.

The optional

exptime

argument specifies expiration time (in seconds) for the inserted key-value pair. The time resolution is

0.001

seconds. If the

exptime

takes the value

0

(which is the default), then the item will never expire.

The optional

flags

argument specifies a user flags value associated with the entry to be stored. It can also be retrieved later with the value. The user flags is stored as an unsigned 32-bit integer internally. Defaults to

0

. The user flags argument was first introduced in the

v0.5.0rc2

release.

When it fails to allocate memory for the current key-value item, then

set

will try removing existing items in the storage according to the Least-Recently Used (LRU) algorithm. Note that, LRU takes priority over expiration time here. If up to tens of existing items have been removed and the storage left is still insufficient (either due to the total capacity limit specified by lua_shared_dict or memory segmentation), then the

err

return value will be

no memory

and

success

will be

false

.

If the sizes of items in the dictionary are not multiples or even powers of a certain value (like 2), it is easier to encounter

no memory

error because of memory fragmentation. It is recommended to use different dictionaries for different sizes of items.

When you encounter

no memory

error, you can also evict more least-recently-used items by retrying this method call more times to to make room for the current item.

If this method succeeds in storing the current item by forcibly removing other not-yet-expired items in the dictionary via LRU, the

forcible

return value will be

true

. If it stores the item without forcibly removing other valid items, then the return value

forcible

will be

false

.

The first argument to this method must be the dictionary object itself, for example,

local cats = ngx.shared.cats local succ, err, forcible = cats.set(cats, "Marry", "it is a nice cat!")

or use Lua's syntactic sugar for method calls:

local cats = ngx.shared.cats local succ, err, forcible = cats:set("Marry", "it is a nice cat!")

These two forms are fundamentally equivalent.

This feature was first introduced in the

v0.3.1rc22

release.

Please note that while internally the key-value pair is set atomically, the atomicity does not go across the method call boundary.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.safe_set

syntax: ok, err = ngx.shared.DICT:safe_set(key, value, exptime?, flags?)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Similar to the set method, but never overrides the (least recently used) unexpired items in the store when running out of storage in the shared memory zone. In this case, it will immediately return

nil

and the string "no memory".

This feature was first introduced in the

v0.7.18

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.add

syntax: success, err, forcible = ngx.shared.DICT:add(key, value, exptime?, flags?)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Just like the set method, but only stores the key-value pair into the dictionary ngx.shared.DICT if the key does not exist.

If the

key

argument already exists in the dictionary (and not expired for sure), the

success

return value will be

false

and the

err

return value will be

"exists"

.

This feature was first introduced in the

v0.3.1rc22

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.safe_add

syntax: ok, err = ngx.shared.DICT:safe_add(key, value, exptime?, flags?)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Similar to the add method, but never overrides the (least recently used) unexpired items in the store when running out of storage in the shared memory zone. In this case, it will immediately return

nil

and the string "no memory".

This feature was first introduced in the

v0.7.18

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.replace

syntax: success, err, forcible = ngx.shared.DICT:replace(key, value, exptime?, flags?)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Just like the set method, but only stores the key-value pair into the dictionary ngx.shared.DICT if the key does exist.

If the

key

argument does not exist in the dictionary (or expired already), the

success

return value will be

false

and the

err

return value will be

"not found"

.

This feature was first introduced in the

v0.3.1rc22

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.delete

syntax: ngx.shared.DICT:delete(key)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Unconditionally removes the key-value pair from the shm-based dictionary ngx.shared.DICT.

It is equivalent to

ngx.shared.DICT:set(key, nil)

.

This feature was first introduced in the

v0.3.1rc22

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.incr

syntax: newval, err, forcible? = ngx.shared.DICT:incr(key, value, init?, init_ttl?)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

optional requirement:

resty.core.shdict

or

resty.core

Increments the (numerical) value for

key

in the shm-based dictionary ngx.shared.DICT by the step value

value

. Returns the new resulting number if the operation is successfully completed or

nil

and an error message otherwise.

When the key does not exist or has already expired in the shared dictionary,

  1. if the
    init
    argument is not specified or takes the value
    nil
    , this method will return
    nil
    and the error string
    "not found"
    , or
  2. if the
    init
    argument takes a number value, this method will create a new
    key
    with the value
    init + value
    .

Like the add method, it also overrides the (least recently used) unexpired items in the store when running out of storage in the shared memory zone.

The optional

init\_ttl

argument specifies expiration time (in seconds) of the value when it is initialized via the

init

argument. The time resolution is

0.001

seconds. If

init\_ttl

takes the value

0

(which is the default), then the item will never expire. This argument cannot be provided without providing the

init

argument as well, and has no effect if the value already exists (e.g., if it was previously inserted via set or the likes).

Note: Usage of the

init\_ttl

argument requires the

resty.core.shdict

or

resty.core

modules from the lua-resty-core library. Example:

require "resty.core" local cats = ngx.shared.cats local newval, err = cats:incr("black\_cats", 1, 0, 0.1) print(newval) -- 1 ngx.sleep(0.2) local val, err = cats:get("black\_cats") print(val) -- nil

The

forcible

return value will always be

nil

when the

init

argument is not specified.

If this method succeeds in storing the current item by forcibly removing other not-yet-expired items in the dictionary via LRU, the

forcible

return value will be

true

. If it stores the item without forcibly removing other valid items, then the return value

forcible

will be

false

.

If the original value is not a valid Lua number in the dictionary, it will return

nil

and

"not a number"

.

The

value

argument and

init

argument can be any valid Lua numbers, like negative numbers or floating-point numbers.

This method was first introduced in the

v0.3.1rc22

release.

The optional

init

parameter was first added in the

v0.10.6

release.

The optional

init\_ttl

parameter was introduced in the

v0.10.12rc2

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.lpush

syntax: length, err = ngx.shared.DICT:lpush(key, value)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Inserts the specified (numerical or string)

value

at the head of the list named

key

in the shm-based dictionary ngx.shared.DICT. Returns the number of elements in the list after the push operation.

If

key

does not exist, it is created as an empty list before performing the push operation. When the

key

already takes a value that is not a list, it will return

nil

and

"value not a list"

.

It never overrides the (least recently used) unexpired items in the store when running out of storage in the shared memory zone. In this case, it will immediately return

nil

and the string "no memory".

This feature was first introduced in the

v0.10.6

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.rpush

syntax: length, err = ngx.shared.DICT:rpush(key, value)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Similar to the lpush method, but inserts the specified (numerical or string)

value

at the tail of the list named

key

.

This feature was first introduced in the

v0.10.6

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.lpop

syntax: val, err = ngx.shared.DICT:lpop(key)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Removes and returns the first element of the list named

key

in the shm-based dictionary ngx.shared.DICT.

If

key

does not exist, it will return

nil

. When the

key

already takes a value that is not a list, it will return

nil

and

"value not a list"

.

This feature was first introduced in the

v0.10.6

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.rpop

syntax: val, err = ngx.shared.DICT:rpop(key)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Removes and returns the last element of the list named

key

in the shm-based dictionary ngx.shared.DICT.

If

key

does not exist, it will return

nil

. When the

key

already takes a value that is not a list, it will return

nil

and

"value not a list"

.

This feature was first introduced in the

v0.10.6

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.llen

syntax: len, err = ngx.shared.DICT:llen(key)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Returns the number of elements in the list named

key

in the shm-based dictionary ngx.shared.DICT.

If key does not exist, it is interpreted as an empty list and 0 is returned. When the

key

already takes a value that is not a list, it will return

nil

and

"value not a list"

.

This feature was first introduced in the

v0.10.6

release.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.ttl

syntax: ttl, err = ngx.shared.DICT:ttl(key)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

requires:

resty.core.shdict

or

resty.core

Retrieves the remaining TTL (time-to-live in seconds) of a key-value pair in the shm-based dictionary ngx.shared.DICT. Returns the TTL as a number if the operation is successfully completed or

nil

and an error message otherwise.

If the key does not exist (or has already expired), this method will return

nil

and the error string

"not found"

.

The TTL is originally determined by the

exptime

argument of the set, add, replace (and the likes) methods. It has a time resolution of

0.001

seconds. A value of

0

means that the item will never expire.

Example:

require "resty.core" local cats = ngx.shared.cats local succ, err = cats:set("Marry", "a nice cat", 0.5) ngx.sleep(0.2) local ttl, err = cats:ttl("Marry") ngx.say(ttl) -- 0.3

This feature was first introduced in the

v0.10.11

release.

Note: This method requires the

resty.core.shdict

or

resty.core

modules from the lua-resty-core library.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.expire

syntax: success, err = ngx.shared.DICT:expire(key, exptime)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

requires:

resty.core.shdict

or

resty.core

Updates the

exptime

(in second) of a key-value pair in the shm-based dictionary ngx.shared.DICT. Returns a boolean indicating success if the operation completes or

nil

and an error message otherwise.

If the key does not exist, this method will return

nil

and the error string

"not found"

.

The

exptime

argument has a resolution of

0.001

seconds. If

exptime

is

0

, then the item will never expire.

Example:

require "resty.core" local cats = ngx.shared.cats local succ, err = cats:set("Marry", "a nice cat", 0.1) succ, err = cats:expire("Marry", 0.5) ngx.sleep(0.2) local val, err = cats:get("Marry") ngx.say(val) -- "a nice cat"

This feature was first introduced in the

v0.10.11

release.

Note: This method requires the

resty.core.shdict

or

resty.core

modules from the lua-resty-core library.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.flush_all

syntax: ngx.shared.DICT:flush_all()

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Flushes out all the items in the dictionary. This method does not actually free up all the memory blocks in the dictionary but just marks all the existing items as expired.

This feature was first introduced in the

v0.5.0rc17

release.

See also ngx.shared.DICT.flush_expired and ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.flush_expired

syntax: flushed = ngx.shared.DICT:flushexpired(maxcount?)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Flushes out the expired items in the dictionary, up to the maximal number specified by the optional

max\_count

argument. When the

max\_count

argument is given

0

or not given at all, then it means unlimited. Returns the number of items that have actually been flushed.

Unlike the flush_all method, this method actually frees up the memory used by the expired items.

This feature was first introduced in the

v0.6.3

release.

See also ngx.shared.DICT.flush_all and ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.get_keys

syntax: keys = ngx.shared.DICT:getkeys(maxcount?)

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Fetch a list of the keys from the dictionary, up to

<max_count></max_count>

.

By default, only the first 1024 keys (if any) are returned. When the

<max_count></max_count>

argument is given the value

0

, then all the keys will be returned even there is more than 1024 keys in the dictionary.

CAUTION Avoid calling this method on dictionaries with a very large number of keys as it may lock the dictionary for significant amount of time and block Nginx worker processes trying to access the dictionary.

This feature was first introduced in the

v0.7.3

release.

Back to TOC

ngx.shared.DICT.capacity

syntax: capacity_bytes = ngx.shared.DICT:capacity()

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

requires:

resty.core.shdict

or

resty.core

Retrieves the capacity in bytes for the shm-based dictionary ngx.shared.DICT declared with the lua_shared_dict directive.

Example:

require "resty.core.shdict" local cats = ngx.shared.cats local capacity\_bytes = cats:capacity()

This feature was first introduced in the

v0.10.11

release.

Note: This method requires the

resty.core.shdict

or

resty.core

modules from the lua-resty-core library.

This feature requires at least Nginx core version

0.7.3

.

See also ngx.shared.DICT.

Back to TOC

ngx.shared.DICT.free_space

syntax: freepagebytes = ngx.shared.DICT:free_space()

context: initbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

requires:

resty.core.shdict

or

resty.core

Retrieves the free page size in bytes for the shm-based dictionary ngx.shared.DICT.

Note: The memory for ngx.shared.DICT is allocated via the Nginx slab allocator which has each slot for data size ranges like 8, 916, 1732, ..., 10252048, 2048~ bytes. And pages are assigned to a slot if there is no room in already assigned pages for the slot.

So even if the return value of the

free\_space

method is zero, there may be room in already assigned pages, so you may successfully set a new key value pair to the shared dict without getting

true

for

forcible

or non nil

err

from the

ngx.shared.DICT.set

.

On the other hand, if already assigned pages for a slot are full and a new key value pair is added to the slot and there is no free page, you may get

true

for

forcible

or non nil

err

from the

ngx.shared.DICT.set

method.

Example:

require "resty.core.shdict" local cats = ngx.shared.cats local free\_page\_bytes = cats:free\_space()

This feature was first introduced in the

v0.10.11

release.

Note: This method requires the

resty.core.shdict

or

resty.core

modules from the lua-resty-core library.

This feature requires at least Nginx core version

1.11.7

.

See also ngx.shared.DICT.

Back to TOC

ngx.socket.udp

syntax: udpsock = ngx.socket.udp()

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Creates and returns a UDP or datagram-oriented unix domain socket object (also known as one type of the "cosocket" objects). The following methods are supported on this object:

It is intended to be compatible with the UDP API of the LuaSocket library but is 100% nonblocking out of the box.

This feature was first introduced in the

v0.5.7

release.

See also ngx.socket.tcp.

Back to TOC

udpsock:setpeername

syntax: ok, err = udpsock:setpeername(host, port)

syntax: ok, err = udpsock:setpeername("unix:/path/to/unix-domain.socket")

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Attempts to connect a UDP socket object to a remote server or to a datagram unix domain socket file. Because the datagram protocol is actually connection-less, this method does not really establish a "connection", but only just set the name of the remote peer for subsequent read/write operations.

Both IP addresses and domain names can be specified as the

host

argument. In case of domain names, this method will use Nginx core's dynamic resolver to parse the domain name without blocking and it is required to configure the resolver directive in the

nginx.conf

file like this:

resolver 8.8.8.8; # use Google's public DNS nameserver

If the nameserver returns multiple IP addresses for the host name, this method will pick up one randomly.

In case of error, the method returns

nil

followed by a string describing the error. In case of success, the method returns

1

.

Here is an example for connecting to a UDP (memcached) server:

location /test { resolver 8.8.8.8; content\_by\_lua\_block { local sock = ngx.socket.udp() local ok, err = sock:setpeername("my.memcached.server.domain", 11211) if not ok then ngx.say("failed to connect to memcached: ", err) return end ngx.say("successfully connected to memcached!") sock:close() } }

Since the

v0.7.18

release, connecting to a datagram unix domain socket file is also possible on Linux:

local sock = ngx.socket.udp() local ok, err = sock:setpeername("unix:/tmp/some-datagram-service.sock") if not ok then ngx.say("failed to connect to the datagram unix domain socket: ", err) return end -- do something after connect -- such as sock:send or sock:receive

assuming the datagram service is listening on the unix domain socket file

/tmp/some-datagram-service.sock

and the client socket will use the "autobind" feature on Linux.

Calling this method on an already connected socket object will cause the original connection to be closed first.

This method was first introduced in the

v0.5.7

release.

Back to TOC

udpsock:send

syntax: ok, err = udpsock:send(data)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Sends data on the current UDP or datagram unix domain socket object.

In case of success, it returns

1

. Otherwise, it returns

nil

and a string describing the error.

The input argument

data

can either be a Lua string or a (nested) Lua table holding string fragments. In case of table arguments, this method will copy all the string elements piece by piece to the underlying Nginx socket send buffers, which is usually optimal than doing string concatenation operations on the Lua land.

This feature was first introduced in the

v0.5.7

release.

Back to TOC

udpsock:receive

syntax: data, err = udpsock:receive(size?)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Receives data from the UDP or datagram unix domain socket object with an optional receive buffer size argument,

size

.

This method is a synchronous operation and is 100% nonblocking.

In case of success, it returns the data received; in case of error, it returns

nil

with a string describing the error.

If the

size

argument is specified, then this method will use this size as the receive buffer size. But when this size is greater than

8192

, then

8192

will be used instead.

If no argument is specified, then the maximal buffer size,

8192

is assumed.

Timeout for the reading operation is controlled by the lua_socket_read_timeout config directive and the settimeout method. And the latter takes priority. For example:

sock:settimeout(1000) -- one second timeout local data, err = sock:receive() if not data then ngx.say("failed to read a packet: ", err) return end ngx.say("successfully read a packet: ", data)

It is important here to call the settimeout method before calling this method.

This feature was first introduced in the

v0.5.7

release.

Back to TOC

udpsock:close

syntax: ok, err = udpsock:close()

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Closes the current UDP or datagram unix domain socket. It returns the

1

in case of success and returns

nil

with a string describing the error otherwise.

Socket objects that have not invoked this method (and associated connections) will be closed when the socket object is released by the Lua GC (Garbage Collector) or the current client HTTP request finishes processing.

This feature was first introduced in the

v0.5.7

release.

Back to TOC

udpsock:settimeout

syntax: udpsock:settimeout(time)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Set the timeout value in milliseconds for subsequent socket operations (like receive).

Settings done by this method takes priority over those config directives, like lua_socket_read_timeout.

This feature was first introduced in the

v0.5.7

release.

Back to TOC

ngx.socket.stream

Just an alias to ngx.socket.tcp. If the stream-typed cosocket may also connect to a unix domain socket, then this API name is preferred.

This API function was first added to the

v0.10.1

release.

Back to TOC

ngx.socket.tcp

syntax: tcpsock = ngx.socket.tcp()

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Creates and returns a TCP or stream-oriented unix domain socket object (also known as one type of the "cosocket" objects). The following methods are supported on this object:

It is intended to be compatible with the TCP API of the LuaSocket library but is 100% nonblocking out of the box. Also, we introduce some new APIs to provide more functionalities.

The cosocket object created by this API function has exactly the same lifetime as the Lua handler creating it. So never pass the cosocket object to any other Lua handler (including ngx.timer callback functions) and never share the cosocket object between different Nginx requests.

For every cosocket object's underlying connection, if you do not explicitly close it (via close) or put it back to the connection pool (via setkeepalive), then it is automatically closed when one of the following two events happens:

  • the current request handler completes, or
  • the Lua cosocket object value gets collected by the Lua GC.

Fatal errors in cosocket operations always automatically close the current connection (note that, read timeout error is the only error that is not fatal), and if you call close on a closed connection, you will get the "closed" error.

Starting from the

0.9.9

release, the cosocket object here is full-duplex, that is, a reader "light thread" and a writer "light thread" can operate on a single cosocket object simultaneously (both "light threads" must belong to the same Lua handler though, see reasons above). But you cannot have two "light threads" both reading (or writing or connecting) the same cosocket, otherwise you might get an error like "socket busy reading" when calling the methods of the cosocket object.

This feature was first introduced in the

v0.5.0rc1

release.

See also ngx.socket.udp.

Back to TOC

tcpsock:connect

syntax: ok, err = tcpsock:connect(host, port, options_table?)

syntax: ok, err = tcpsock:connect("unix:/path/to/unix-domain.socket", options_table?)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Attempts to connect a TCP socket object to a remote server or to a stream unix domain socket file without blocking.

Before actually resolving the host name and connecting to the remote backend, this method will always look up the connection pool for matched idle connections created by previous calls of this method (or the ngx.socket.connect function).

Both IP addresses and domain names can be specified as the

host

argument. In case of domain names, this method will use Nginx core's dynamic resolver to parse the domain name without blocking and it is required to configure the resolver directive in the

nginx.conf

file like this:

resolver 8.8.8.8; # use Google's public DNS nameserver

If the nameserver returns multiple IP addresses for the host name, this method will pick up one randomly.

In case of error, the method returns

nil

followed by a string describing the error. In case of success, the method returns

1

.

Here is an example for connecting to a TCP server:

location /test { resolver 8.8.8.8; content\_by\_lua\_block { local sock = ngx.socket.tcp() local ok, err = sock:connect("www.google.com", 80) if not ok then ngx.say("failed to connect to google: ", err) return end ngx.say("successfully connected to google!") sock:close() } }

Connecting to a Unix Domain Socket file is also possible:

local sock = ngx.socket.tcp() local ok, err = sock:connect("unix:/tmp/memcached.sock") if not ok then ngx.say("failed to connect to the memcached unix domain socket: ", err) return end -- do something after connect -- such as sock:send or sock:receive

assuming memcached (or something else) is listening on the unix domain socket file

/tmp/memcached.sock

.

Timeout for the connecting operation is controlled by the lua_socket_connect_timeout config directive and the settimeout method. And the latter takes priority. For example:

local sock = ngx.socket.tcp() sock:settimeout(1000) -- one second timeout local ok, err = sock:connect(host, port)

It is important here to call the settimeout method before calling this method.

Calling this method on an already connected socket object will cause the original connection to be closed first.

An optional Lua table can be specified as the last argument to this method to specify various connect options:

  • pool

    specify a custom name for the connection pool being used. If omitted, then the connection pool name will be generated from the string template

    "<host>:<port>"</port></host>

    or

    "<unix-socket-path>"</unix-socket-path>

    .

pool\_size

specify the size of the connection pool. If omitted and no

backlog

option was provided, no pool will be created. If omitted but

backlog

was provided, the pool will be created with a default size equal to the value of the lua_socket_pool_sizedirective. The connection pool holds up to

pool\_size

alive connections ready to be reused by subsequent calls to connect, but note that there is no upper limit to the total number of opened connections outside of the pool. If you need to restrict the total number of opened connections, specify the

backlog

option. When the connection pool would exceed its size limit, the least recently used (kept-alive) connection already in the pool will be closed to make room for the current connection. Note that the cosocket connection pool is per Nginx worker process rather than per Nginx server instance, so the size limit specified here also applies to every single Nginx worker process. Also note that the size of the connection pool cannot be changed once it has been created. This option was first introduced in the

v0.10.14

release.

backlog

if specified, this module will limit the total number of opened connections for this pool. No more connections than

pool\_size

can be opened for this pool at any time. If the connection pool is full, subsequent connect operations will be queued into a queue equal to this option's value (the "backlog" queue). If the number of queued connect operations is equal to

backlog

, subsequent connect operations will fail and return

nil

plus the error string

"too many waiting connect operations"

. The queued connect operations will be resumed once the number of connections in the pool is less than

pool\_size

. The queued connect operation will abort once they have been queued for more than

connect\_timeout

, controlled bysettimeouts, and will return

nil

plus the error string

"timeout"

. This option was first introduced in the

v0.10.14

release.

The support for the options table argument was first introduced in the

v0.5.7

release.

This method was first introduced in the

v0.5.0rc1

release.

Back to TOC

tcpsock:sslhandshake

syntax: session, err = tcpsock:sslhandshake(reusedsession?, servername?, sslverify?, sendstatus_req?)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Does SSL/TLS handshake on the currently established connection.

The optional

reused\_session

argument can take a former SSL session userdata returned by a previous

sslhandshake

call for exactly the same target. For short-lived connections, reusing SSL sessions can usually speed up the handshake by one order by magnitude but it is not so useful if the connection pool is enabled. This argument defaults to

nil

. If this argument takes the boolean

false

value, no SSL session userdata would return by this call and only a Lua boolean will be returned as the first return value; otherwise the current SSL session will always be returned as the first argument in case of successes.

The optional

server\_name

argument is used to specify the server name for the new TLS extension Server Name Indication (SNI). Use of SNI can make different servers share the same IP address on the server side. Also, when SSL verification is enabled, this

server\_name

argument is also used to validate the server name specified in the server certificate sent from the remote.

The optional

ssl\_verify

argument takes a Lua boolean value to control whether to perform SSL verification. When set to

true

, the server certificate will be verified according to the CA certificates specified by the lua_ssl_trusted_certificate directive. You may also need to adjust the lua_ssl_verify_depthdirective to control how deep we should follow along the certificate chain. Also, when the

ssl\_verify

argument is true and the

server\_name

argument is also specified, the latter will be used to validate the server name in the server certificate.

The optional

send\_status\_req

argument takes a boolean that controls whether to send the OCSP status request in the SSL handshake request (which is for requesting OCSP stapling).

For connections that have already done SSL/TLS handshake, this method returns immediately.

This method was first introduced in the

v0.9.11

release.

Back to TOC

tcpsock:send

syntax: bytes, err = tcpsock:send(data)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Sends data without blocking on the current TCP or Unix Domain Socket connection.

This method is a synchronous operation that will not return until all the data has been flushed into the system socket send buffer or an error occurs.

In case of success, it returns the total number of bytes that have been sent. Otherwise, it returns

nil

and a string describing the error.

The input argument

data

can either be a Lua string or a (nested) Lua table holding string fragments. In case of table arguments, this method will copy all the string elements piece by piece to the underlying Nginx socket send buffers, which is usually optimal than doing string concatenation operations on the Lua land.

Timeout for the sending operation is controlled by the lua_socket_send_timeout config directive and the settimeout method. And the latter takes priority. For example:

sock:settimeout(1000) -- one second timeout local bytes, err = sock:send(request)

It is important here to call the settimeout method before calling this method.

In case of any connection errors, this method always automatically closes the current connection.

This feature was first introduced in the

v0.5.0rc1

release.

Back to TOC

tcpsock:receive

syntax: data, err, partial = tcpsock:receive(size)

syntax: data, err, partial = tcpsock:receive(pattern?)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Receives data from the connected socket according to the reading pattern or size.

This method is a synchronous operation just like the send method and is 100% nonblocking.

In case of success, it returns the data received; in case of error, it returns

nil

with a string describing the error and the partial data received so far.

If a number-like argument is specified (including strings that look like numbers), then it is interpreted as a size. This method will not return until it reads exactly this size of data or an error occurs.

If a non-number-like string argument is specified, then it is interpreted as a "pattern". The following patterns are supported:

  • '\*a'
    : reads from the socket until the connection is closed. No end-of-line translation is performed;
  • '\*l'
    : reads a line of text from the socket. The line is terminated by a
    Line Feed
    (LF) character (ASCII 10), optionally preceded by a
    Carriage Return
    (CR) character (ASCII 13). The CR and LF characters are not included in the returned line. In fact, all CR characters are ignored by the pattern.

If no argument is specified, then it is assumed to be the pattern

'\*l'

, that is, the line reading pattern.

Timeout for the reading operation is controlled by the lua_socket_read_timeout config directive and the settimeout method. And the latter takes priority. For example:

sock:settimeout(1000) -- one second timeout local line, err, partial = sock:receive() if not line then ngx.say("failed to read a line: ", err) return end ngx.say("successfully read a line: ", line)

It is important here to call the settimeout method before calling this method.

Since the

v0.8.8

release, this method no longer automatically closes the current connection when the read timeout error happens. For other connection errors, this method always automatically closes the connection.

This feature was first introduced in the

v0.5.0rc1

release.

Back to TOC

tcpsock:receiveany

syntax: data, err = tcpsock:receiveany(max)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Returns any data received by the connected socket, at most

max

bytes.

This method is a synchronous operation just like the send method and is 100% nonblocking.

In case of success, it returns the data received; in case of error, it returns

nil

with a string describing the error.

If the received data is more than this size, this method will return with exactly this size of data. The remaining data in the underlying receive buffer could be returned in the next reading operation.

Timeout for the reading operation is controlled by the lua_socket_read_timeout config directive and the settimeouts method. And the latter takes priority. For example:

sock:settimeouts(1000, 1000, 1000) -- one second timeout for connect/read/write local data, err = sock:receiveany(10 \* 1024) -- read any data, at most 10K if not data then ngx.say("failed to read any data: ", err) return end ngx.say("successfully read: ", data)

This method doesn't automatically close the current connection when the read timeout error occurs. For other connection errors, this method always automatically closes the connection.

This feature was first introduced in the

v0.10.14

release.

Back to TOC

tcpsock:receiveuntil

syntax: iterator = tcpsock:receiveuntil(pattern, options?)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

This method returns an iterator Lua function that can be called to read the data stream until it sees the specified pattern or an error occurs.

Here is an example for using this method to read a data stream with the boundary sequence

--abcedhb

:

local reader = sock:receiveuntil("\r\n--abcedhb") local data, err, partial = reader() if not data then ngx.say("failed to read the data stream: ", err) end ngx.say("read the data stream: ", data)

When called without any argument, the iterator function returns the received data right before the specified pattern string in the incoming data stream. So for the example above, if the incoming data stream is

'hello, world! -agentzh\r\n--abcedhb blah blah'

, then the string

'hello, world! -agentzh'

will be returned.

In case of error, the iterator function will return

nil

along with a string describing the error and the partial data bytes that have been read so far.

The iterator function can be called multiple times and can be mixed safely with other cosocket method calls or other iterator function calls.

The iterator function behaves differently (i.e., like a real iterator) when it is called with a

size

argument. That is, it will read that

size

of data on each invocation and will return

nil

at the last invocation (either sees the boundary pattern or meets an error). For the last successful invocation of the iterator function, the

err

return value will be

nil

too. The iterator function will be reset after the last successful invocation that returns

nil

data and

nil

error. Consider the following example:

local reader = sock:receiveuntil("\r\n--abcedhb") while true do local data, err, partial = reader(4) if not data then if err then ngx.say("failed to read the data stream: ", err) break end ngx.say("read done") break end ngx.say("read chunk: [", data, "]") end

Then for the incoming data stream

'hello, world! -agentzh\r\n--abcedhb blah blah'

, we shall get the following output from the sample code above:

read chunk: [hell] read chunk: [o, w] read chunk: [orld] read chunk: [! -a] read chunk: [gent] read chunk: [zh] read done

Note that, the actual data returned might be a little longer than the size limit specified by the

size

argument when the boundary pattern has ambiguity for streaming parsing. Near the boundary of the data stream, the data string actually returned could also be shorter than the size limit.

Timeout for the iterator function's reading operation is controlled by the lua_socket_read_timeout config directive and the settimeout method. And the latter takes priority. For example:

local readline = sock:receiveuntil("\r\n") sock:settimeout(1000) -- one second timeout line, err, partial = readline() if not line then ngx.say("failed to read a line: ", err) return end ngx.say("successfully read a line: ", line)

It is important here to call the settimeout method before calling the iterator function (note that the

receiveuntil

call is irrelevant here).

As from the

v0.5.1

release, this method also takes an optional

options

table argument to control the behavior. The following options are supported:

inclusive

The

inclusive

takes a boolean value to control whether to include the pattern string in the returned data string. Default to

false

. For example,

local reader = tcpsock:receiveuntil("\_END\_", { inclusive = true }) local data = reader() ngx.say(data)

Then for the input data stream

"hello world \_END\_ blah blah blah"

, then the example above will output

hello world \_END\_

, including the pattern string

\_END\_

itself.

Since the

v0.8.8

release, this method no longer automatically closes the current connection when the read timeout error happens. For other connection errors, this method always automatically closes the connection.

This method was first introduced in the

v0.5.0rc1

release.

Back to TOC

tcpsock:close

syntax: ok, err = tcpsock:close()

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Closes the current TCP or stream unix domain socket. It returns the

1

in case of success and returns

nil

with a string describing the error otherwise.

Note that there is no need to call this method on socket objects that have invoked the setkeepalive method because the socket object is already closed (and the current connection is saved into the built-in connection pool).

Socket objects that have not invoked this method (and associated connections) will be closed when the socket object is released by the Lua GC (Garbage Collector) or the current client HTTP request finishes processing.

This feature was first introduced in the

v0.5.0rc1

release.

Back to TOC

tcpsock:settimeout

syntax: tcpsock:settimeout(time)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Set the timeout value in milliseconds for subsequent socket operations (connect, receive, and iterators returned from receiveuntil).

Settings done by this method take priority over those specified via config directives (i.e. lua_socket_connect_timeout, lua_socket_send_timeout, and lua_socket_read_timeout).

Note that this method does not affect the lua_socket_keepalive_timeout setting; the

timeout

argument to the setkeepalive method should be used for this purpose instead.

This feature was first introduced in the

v0.5.0rc1

release.

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tcpsock:settimeouts

syntax: tcpsock:settimeouts(connecttimeout, sendtimeout, read_timeout)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Respectively sets the connect, send, and read timeout thresholds (in milliseconds) for subsequent socket operations (connect, send, receive, and iterators returned from receiveuntil).

Settings done by this method take priority over those specified via config directives (i.e. lua_socket_connect_timeout, lua_socket_send_timeout, and lua_socket_read_timeout).

It is recommended to use settimeouts instead of settimeout.

Note that this method does not affect the lua_socket_keepalive_timeout setting; the

timeout

argument to the setkeepalive method should be used for this purpose instead.

This feature was first introduced in the

v0.10.7

release.

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tcpsock:setoption

syntax: tcpsock:setoption(option, value?)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

This function is added for LuaSocket API compatibility and does nothing for now. Its functionality will be implemented in future.

This feature was first introduced in the

v0.5.0rc1

release.

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tcpsock:setkeepalive

syntax: ok, err = tcpsock:setkeepalive(timeout?, size?)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Puts the current socket's connection immediately into the cosocket built-in connection pool and keep it alive until other connect method calls request it or the associated maximal idle timeout is expired.

The first optional argument,

timeout

, can be used to specify the maximal idle timeout (in milliseconds) for the current connection. If omitted, the default setting in the lua_socket_keepalive_timeout config directive will be used. If the

0

value is given, then the timeout interval is unlimited.

The second optional argument

size

is considered deprecated since the

v0.10.14

release of this module, in favor of the

pool\_size

option of the connect method. Since the

v0.10.14

release, this option will only take effect if the call to connect did not already create a connection pool. When this option takes effect (no connection pool was previously created byconnect), it will specify the size of the connection pool, and create it. If omitted (and no pool was previously created), the default size is the value of the lua_socket_pool_size directive. The connection pool holds up to

size

alive connections ready to be reused by subsequent calls to connect, but note that there is no upper limit to the total number of opened connections outside of the pool. When the connection pool would exceed its size limit, the least recently used (kept-alive) connection already in the pool will be closed to make room for the current connection. Note that the cosocket connection pool is per Nginx worker process rather than per Nginx server instance, so the size limit specified here also applies to every single Nginx worker process. Also note that the size of the connection pool cannot be changed once it has been created. If you need to restrict the total number of opened connections, specify both the

pool\_size

and

backlog

option in the call toconnect.

In case of success, this method returns

1

; otherwise, it returns

nil

and a string describing the error.

When the system receive buffer for the current connection has unread data, then this method will return the "connection in dubious state" error message (as the second return value) because the previous session has unread data left behind for the next session and the connection is not safe to be reused.

This method also makes the current cosocket object enter the "closed" state, so there is no need to manually call the close method on it afterwards.

This feature was first introduced in the

v0.5.0rc1

release.

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tcpsock:getreusedtimes

syntax: count, err = tcpsock:getreusedtimes()

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

This method returns the (successfully) reused times for the current connection. In case of error, it returns

nil

and a string describing the error.

If the current connection does not come from the built-in connection pool, then this method always returns

0

, that is, the connection has never been reused (yet). If the connection comes from the connection pool, then the return value is always non-zero. So this method can also be used to determine if the current connection comes from the pool.

This feature was first introduced in the

v0.5.0rc1

release.

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ngx.socket.connect

syntax: tcpsock, err = ngx.socket.connect(host, port)

syntax: tcpsock, err = ngx.socket.connect("unix:/path/to/unix-domain.socket")

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*

This function is a shortcut for combining ngx.socket.tcp() and the connect() method call in a single operation. It is actually implemented like this:

local sock = ngx.socket.tcp() local ok, err = sock:connect(...) if not ok then return nil, err end return sock

There is no way to use the settimeout method to specify connecting timeout for this method and the lua_socket_connect_timeout directive must be set at configure time instead.

This feature was first introduced in the

v0.5.0rc1

release.

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ngx.get_phase

syntax: str = ngx.get_phase()

context: initbylua*, initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Retrieves the current running phase name. Possible return values are

This API was first introduced in the

v0.5.10

release.

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ngx.thread.spawn

syntax: co = ngx.thread.spawn(func, arg1, arg2, ...)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Spawns a new user "light thread" with the Lua function

func

as well as those optional arguments

arg1

,

arg2

, and etc. Returns a Lua thread (or Lua coroutine) object represents this "light thread".

"Light threads" are just a special kind of Lua coroutines that are scheduled by the ngx_lua module.

Before

ngx.thread.spawn

returns, the

func

will be called with those optional arguments until it returns, aborts with an error, or gets yielded due to I/O operations via the Nginx API for Lua (like tcpsock:receive).

After

ngx.thread.spawn

returns, the newly-created "light thread" will keep running asynchronously usually at various I/O events.

All the Lua code chunks running by rewrite_by_lua, access_by_lua, and content_by_lua are in a boilerplate "light thread" created automatically by ngx_lua. Such boilerplate "light thread" are also called "entry threads".

By default, the corresponding Nginx handler (e.g., rewrite_by_lua handler) will not terminate until

  1. both the "entry thread" and all the user "light threads" terminates,
  2. a "light thread" (either the "entry thread" or a user "light thread") aborts by calling ngx.exit, ngx.exec, ngx.redirect, or ngx.req.set_uri(uri, true), or
  3. the "entry thread" terminates with a Lua error.

When the user "light thread" terminates with a Lua error, however, it will not abort other running "light threads" like the "entry thread" does.

Due to the limitation in the Nginx subrequest model, it is not allowed to abort a running Nginx subrequest in general. So it is also prohibited to abort a running "light thread" that is pending on one ore more Nginx subrequests. You must call ngx.thread.wait to wait for those "light thread" to terminate before quitting the "world". A notable exception here is that you can abort pending subrequests by calling ngx.exit with and only with the status code

ngx.ERROR

(-1),

408

,

444

, or

499

.

The "light threads" are not scheduled in a pre-emptive way. In other words, no time-slicing is performed automatically. A "light thread" will keep running exclusively on the CPU until

  1. a (nonblocking) I/O operation cannot be completed in a single run,
  2. it calls coroutine.yield to actively give up execution, or
  3. it is aborted by a Lua error or an invocation of ngx.exit, ngx.exec, ngx.redirect, or ngx.req.set_uri(uri, true).

For the first two cases, the "light thread" will usually be resumed later by the ngx_lua scheduler unless a "stop-the-world" event happens.

User "light threads" can create "light threads" themselves. And normal user coroutines created by coroutine.create can also create "light threads". The coroutine (be it a normal Lua coroutine or a "light thread") that directly spawns the "light thread" is called the "parent coroutine" for the "light thread" newly spawned.

The "parent coroutine" can call ngx.thread.wait to wait on the termination of its child "light thread".

You can call coroutine.status() and coroutine.yield() on the "light thread" coroutines.

The status of the "light thread" coroutine can be "zombie" if

  1. the current "light thread" already terminates (either successfully or with an error),
  2. its parent coroutine is still alive, and
  3. its parent coroutine is not waiting on it with ngx.thread.wait.

The following example demonstrates the use of coroutine.yield() in the "light thread" coroutines to do manual time-slicing:

local yield = coroutine.yield function f() local self = coroutine.running() ngx.say("f 1") yield(self) ngx.say("f 2") yield(self) ngx.say("f 3") end local self = coroutine.running() ngx.say("0") yield(self) ngx.say("1") ngx.thread.spawn(f) ngx.say("2") yield(self) ngx.say("3") yield(self) ngx.say("4")

Then it will generate the output

0 1 f 1 2 f 2 3 f 3 4

"Light threads" are mostly useful for making concurrent upstream requests in a single Nginx request handler, much like a generalized version of ngx.location.capture_multi that can work with all the Nginx API for Lua. The following example demonstrates parallel requests to MySQL, Memcached, and upstream HTTP services in a single Lua handler, and outputting the results in the order that they actually return (similar to Facebook's BigPipe model):

-- query mysql, memcached, and a remote http service at the same time, -- output the results in the order that they -- actually return the results. local mysql = require "resty.mysql" local memcached = require "resty.memcached" local function query\_mysql() local db = mysql:new() db:connect{ host = "127.0.0.1", port = 3306, database = "test", user = "monty", password = "mypass" } local res, err, errno, sqlstate = db:query("select \* from cats order by id asc") db:set\_keepalive(0, 100) ngx.say("mysql done: ", cjson.encode(res)) end local function query\_memcached() local memc = memcached:new() memc:connect("127.0.0.1", 11211) local res, err = memc:get("some\_key") ngx.say("memcached done: ", res) end local function query\_http() local res = ngx.location.capture("/my-http-proxy") ngx.say("http done: ", res.body) end ngx.thread.spawn(query\_mysql) -- create thread 1 ngx.thread.spawn(query\_memcached) -- create thread 2 ngx.thread.spawn(query\_http) -- create thread 3

This API was first enabled in the

v0.7.0

release.

Back to TOC

ngx.thread.wait

syntax: ok, res1, res2, ... = ngx.thread.wait(thread1, thread2, ...)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Waits on one or more child "light threads" and returns the results of the first "light thread" that terminates (either successfully or with an error).

The arguments

thread1

,

thread2

, and etc are the Lua thread objects returned by earlier calls of ngx.thread.spawn.

The return values have exactly the same meaning as coroutine.resume, that is, the first value returned is a boolean value indicating whether the "light thread" terminates successfully or not, and subsequent values returned are the return values of the user Lua function that was used to spawn the "light thread" (in case of success) or the error object (in case of failure).

Only the direct "parent coroutine" can wait on its child "light thread", otherwise a Lua exception will be raised.

The following example demonstrates the use of

ngx.thread.wait

and ngx.location.capture to emulate ngx.location.capture_multi:

local capture = ngx.location.capture local spawn = ngx.thread.spawn local wait = ngx.thread.wait local say = ngx.say local function fetch(uri) return capture(uri) end local threads = { spawn(fetch, "/foo"), spawn(fetch, "/bar"), spawn(fetch, "/baz") } for i = 1, #threads do local ok, res = wait(threads[i]) if not ok then say(i, ": failed to run: ", res) else say(i, ": status: ", res.status) say(i, ": body: ", res.body) end end

Here it essentially implements the "wait all" model.

And below is an example demonstrating the "wait any" model:

function f() ngx.sleep(0.2) ngx.say("f: hello") return "f done" end function g() ngx.sleep(0.1) ngx.say("g: hello") return "g done" end local tf, err = ngx.thread.spawn(f) if not tf then ngx.say("failed to spawn thread f: ", err) return end ngx.say("f thread created: ", coroutine.status(tf)) local tg, err = ngx.thread.spawn(g) if not tg then ngx.say("failed to spawn thread g: ", err) return end ngx.say("g thread created: ", coroutine.status(tg)) ok, res = ngx.thread.wait(tf, tg) if not ok then ngx.say("failed to wait: ", res) return end ngx.say("res: ", res) -- stop the "world", aborting other running threads ngx.exit(ngx.OK)

And it will generate the following output:

f thread created: running g thread created: running g: hello res: g done

This API was first enabled in the

v0.7.0

release.

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ngx.thread.kill

syntax: ok, err = ngx.thread.kill(thread)

context: rewritebylua*, accessbylua*, contentbylua*, ngx.timer.*, sslcertificatebylua*, sslsessionfetchby_lua*

Kills a running "light thread" created by ngx.thread.spawn. Returns a true value when successful or

nil

and a string describing the error otherwise.

According to the current implementation, only the parent coroutine (or "light thread") can kill a thread. Also, a running "light thread" with pending Nginx subrequests (initiated by ngx.location.capture for example) cannot be killed due to a limitation in the Nginx core.

This API was first enabled in the

v0.9.9

release.

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ngx.on_abort

syntax: ok, err = ngx.on_abort(callback)

context: rewritebylua*, accessbylua*, contentbylua*

Registers a user Lua function as the callback which gets called automatically when the client closes the (downstream) connection prematurely.

Returns

1

if the callback is registered successfully or returns

nil

and a string describing the error otherwise.

All the Nginx API for Lua can be used in the callback function because the function is run in a special "light thread", just as those "light threads" created by ngx.thread.spawn.

The callback function can decide what to do with the client abortion event all by itself. For example, it can simply ignore the event by doing nothing and the current Lua request handler will continue executing without interruptions. And the callback function can also decide to terminate everything by calling ngx.exit, for example,

local function my\_cleanup() -- custom cleanup work goes here, like cancelling a pending DB transaction -- now abort all the "light threads" running in the current request handler ngx.exit(499) end local ok, err = ngx.on\_abort(my\_cleanup) if not ok then ngx.log(ngx.ERR, "failed to register the on\_abort callback: ", err) ngx.exit(500) end

When lua_check_client_abort is set to

off

(which is the default), then this function call will always return the error message "lua_check_client_abort is off".

According to the current implementation, this function can only be called once in a single request handler; subsequent calls will return the error message "duplicate call".

This API was first introduced in the

v0.7.4

release.

See also lua_check_client_abort.

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ngx.timer.at

syntax: hdl, err = ngx.timer.at(delay, callback, userarg1, userarg2, ...)

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Creates an Nginx timer with a user callback function as well as optional user arguments.

The first argument,

delay

, specifies the delay for the timer, in seconds. One can specify fractional seconds like

0.001

to mean 1 millisecond here.

0

delay can also be specified, in which case the timer will immediately expire when the current handler yields execution.

The second argument,

callback

, can be any Lua function, which will be invoked later in a background "light thread" after the delay specified. The user callback will be called automatically by the Nginx core with the arguments

premature

,

user\_arg1

,

user\_arg2

, and etc, where the

premature

argument takes a boolean value indicating whether it is a premature timer expiration or not, and

user\_arg1

,

user\_arg2

, and etc, are those (extra) user arguments specified when calling

ngx.timer.at

as the remaining arguments.

Premature timer expiration happens when the Nginx worker process is trying to shut down, as in an Nginx configuration reload triggered by the

HUP

signal or in an Nginx server shutdown. When the Nginx worker is trying to shut down, one can no longer call

ngx.timer.at

to create new timers with nonzero delays and in that case

ngx.timer.at

will return a "conditional false" value and a string describing the error, that is, "process exiting".

Starting from the

v0.9.3

release, it is allowed to create zero-delay timers even when the Nginx worker process starts shutting down.

When a timer expires, the user Lua code in the timer callback is running in a "light thread" detached completely from the original request creating the timer. So objects with the same lifetime as the request creating them, like cosockets, cannot be shared between the original request and the timer user callback function.

Here is a simple example:

location / { ... log\_by\_lua\_block { local function push\_data(premature, uri, args, status) -- push the data uri, args, and status to the remote -- via ngx.socket.tcp or ngx.socket.udp -- (one may want to buffer the data in Lua a bit to -- save I/O operations) end local ok, err = ngx.timer.at(0, push\_data, ngx.var.uri, ngx.var.args, ngx.header.status) if not ok then ngx.log(ngx.ERR, "failed to create timer: ", err) return end -- other job in log\_by\_lua\_block } }

One can also create infinite re-occurring timers, for instance, a timer getting triggered every

5

seconds, by calling

ngx.timer.at

recursively in the timer callback function. Here is such an example,

local delay = 5 local handler handler = function (premature) -- do some routine job in Lua just like a cron job if premature then return end local ok, err = ngx.timer.at(delay, handler) if not ok then ngx.log(ngx.ERR, "failed to create the timer: ", err) return end -- do something in timer end local ok, err = ngx.timer.at(delay, handler) if not ok then ngx.log(ngx.ERR, "failed to create the timer: ", err) return end -- do other jobs

It is recommended, however, to use the ngx.timer.every API function instead for creating recurring timers since it is more robust.

Because timer callbacks run in the background and their running time will not add to any client request's response time, they can easily accumulate in the server and exhaust system resources due to either Lua programming mistakes or just too much client traffic. To prevent extreme consequences like crashing the Nginx server, there are built-in limitations on both the number of "pending timers" and the number of "running timers" in an Nginx worker process. The "pending timers" here mean timers that have not yet been expired and "running timers" are those whose user callbacks are currently running.

The maximal number of pending timers allowed in an Nginx worker is controlled by the lua_max_pending_timersdirective. The maximal number of running timers is controlled by thelua_max_running_timers directive.

According to the current implementation, each "running timer" will take one (fake) connection record from the global connection record list configured by the standard worker_connections directive in

nginx.conf

. So ensure that theworker_connections directive is set to a large enough value that takes into account both the real connections and fake connections required by timer callbacks (as limited by thelua_max_running_timers directive).

A lot of the Lua APIs for Nginx are enabled in the context of the timer callbacks, like stream/datagram cosockets (ngx.socket.tcp and ngx.socket.udp), shared memory dictionaries (ngx.shared.DICT), user coroutines (coroutine.*), user "light threads" (ngx.thread.*), ngx.exit, ngx.now/ngx.time,ngx.md5/ngx.sha1_bin, are all allowed. But the subrequest API (likengx.location.capture), the ngx.req.* API, the downstream output API (like ngx.say, ngx.print, and ngx.flush) are explicitly disabled in this context.

You can pass most of the standard Lua values (nils, booleans, numbers, strings, tables, closures, file handles, and etc) into the timer callback, either explicitly as user arguments or implicitly as upvalues for the callback closure. There are several exceptions, however: you cannot pass any thread objects returned by coroutine.create and ngx.thread.spawn or any cosocket objects returned by ngx.socket.tcp, ngx.socket.udp, and ngx.req.socket because these objects' lifetime is bound to the request context creating them while the timer callback is detached from the creating request's context (by design) and runs in its own (fake) request context. If you try to share the thread or cosocket objects across the boundary of the creating request, then you will get the "no co ctx found" error (for threads) or "bad request" (for cosockets). It is fine, however, to create all these objects inside your timer callback.

This API was first introduced in the

v0.8.0

release.

Back to TOC

ngx.timer.every

syntax: hdl, err = ngx.timer.every(delay, callback, userarg1, userarg2, ...)

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Similar to the ngx.timer.at API function, but

  1. delay
    cannot be zero,
  2. timer will be created every
    delay
    seconds until the current Nginx worker process starts exiting.

Like ngx.timer.at, the

callback

argument will be called automatically with the arguments

premature

,

user\_arg1

,

user\_arg2

, etc.

When success, returns a "conditional true" value (but not a

true

). Otherwise, returns a "conditional false" value and a string describing the error.

This API also respect the lua_max_pending_timers and lua_max_running_timers.

This API was first introduced in the

v0.10.9

release.

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ngx.timer.running_count

syntax: count = ngx.timer.running_count()

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Returns the number of timers currently running.

This directive was first introduced in the

v0.9.20

release.

Back to TOC

ngx.timer.pending_count

syntax: count = ngx.timer.pending_count()

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

Returns the number of pending timers.

This directive was first introduced in the

v0.9.20

release.

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ngx.config.subsystem

syntax: subsystem = ngx.config.subsystem

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, initbylua*, initworkerby_lua*

This string field indicates the Nginx subsystem the current Lua environment is based on. For this module, this field always takes the string value

"http"

. Forngx_stream_lua_module, however, this field takes the value

"stream"

.

This field was first introduced in the

0.10.1

.

Back to TOC

ngx.config.debug

syntax: debug = ngx.config.debug

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, initbylua*, initworkerby_lua*

This boolean field indicates whether the current Nginx is a debug build, i.e., being built by the

./configure

option

--with-debug

.

This field was first introduced in the

0.8.7

.

Back to TOC

ngx.config.prefix

syntax: prefix = ngx.config.prefix()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, initbylua*, initworkerby_lua*

Returns the Nginx server "prefix" path, as determined by the

-p

command-line option when running the Nginx executable, or the path specified by the

--prefix

command-line option when building Nginx with the

./configure

script.

This function was first introduced in the

0.9.2

.

Back to TOC

ngx.config.nginx_version

syntax: ver = ngx.config.nginx_version

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, initbylua*, initworkerby_lua*

This field take an integral value indicating the version number of the current Nginx core being used. For example, the version number

1.4.3

results in the Lua number 1004003.

This API was first introduced in the

0.9.3

release.

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ngx.config.nginx_configure

syntax: str = ngx.config.nginx_configure()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, initbylua*

This function returns a string for the Nginx

./configure

command's arguments string.

This API was first introduced in the

0.9.5

release.

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ngx.config.ngx_lua_version

syntax: ver = ngx.config.ngxluaversion

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, initbylua*

This field take an integral value indicating the version number of the current

ngx\_lua

module being used. For example, the version number

0.9.3

results in the Lua number 9003.

This API was first introduced in the

0.9.3

release.

Back to TOC

ngx.worker.exiting

syntax: exiting = ngx.worker.exiting()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, initbylua*, initworkerby_lua*

This function returns a boolean value indicating whether the current Nginx worker process already starts exiting. Nginx worker process exiting happens on Nginx server quit or configuration reload (aka HUP reload).

This API was first introduced in the

0.9.3

release.

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ngx.worker.pid

syntax: pid = ngx.worker.pid()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, initbylua*, initworkerby_lua*

This function returns a Lua number for the process ID (PID) of the current Nginx worker process. This API is more efficient than

ngx.var.pid

and can be used in contexts where the ngx.var.VARIABLE API cannot be used (like init_worker_by_lua).

This API was first introduced in the

0.9.5

release.

Back to TOC

ngx.worker.count

syntax: count = ngx.worker.count()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, initbylua*, initworkerby_lua*

Returns the total number of the Nginx worker processes (i.e., the value configured by the worker_processesdirective in

nginx.conf

).

This API was first introduced in the

0.9.20

release.

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ngx.worker.id

syntax: id = ngx.worker.id()

context: setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, initworkerby_lua*

Returns the ordinal number of the current Nginx worker processes (starting from number 0).

So if the total number of workers is

N

, then this method may return a number between 0 and

N - 1

(inclusive).

This function returns meaningful values only for Nginx 1.9.1+. With earlier versions of Nginx, it always returns

nil

.

See also ngx.worker.count.

This API was first introduced in the

0.9.20

release.

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ngx.semaphore

syntax: local semaphore = require "ngx.semaphore"

This is a Lua module that implements a classic-style semaphore API for efficient synchronizations among different "light threads". Sharing the same semaphore among different "light threads" created in different (request) contexts are also supported as long as the "light threads" reside in the same Nginx worker process and the lua_code_cache directive is turned on (which is the default).

This Lua module does not ship with this ngx_lua module itself rather it is shipped with thelua-resty-core library.

Please refer to the documentationfor this

ngx.semaphore

Lua module in lua-resty-corefor more details.

This feature requires at least ngx_lua

v0.10.0

.

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ngx.balancer

syntax: local balancer = require "ngx.balancer"

This is a Lua module that provides a Lua API to allow defining completely dynamic load balancers in pure Lua.

This Lua module does not ship with this ngx_lua module itself rather it is shipped with thelua-resty-core library.

Please refer to the documentationfor this

ngx.balancer

Lua module in lua-resty-corefor more details.

This feature requires at least ngx_lua

v0.10.0

.

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ngx.ssl

syntax: local ssl = require "ngx.ssl"

This Lua module provides API functions to control the SSL handshake process in contexts likessl_certificate_by_lua*.

This Lua module does not ship with this ngx_lua module itself rather it is shipped with thelua-resty-core library.

Please refer to the documentationfor this

ngx.ssl

Lua module for more details.

This feature requires at least ngx_lua

v0.10.0

.

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ngx.ocsp

syntax: local ocsp = require "ngx.ocsp"

This Lua module provides API to perform OCSP queries, OCSP response validations, and OCSP stapling planting.

Usually, this module is used together with the ngx.sslmodule in the context of ssl_certificate_by_lua*.

This Lua module does not ship with this ngx_lua module itself rather it is shipped with thelua-resty-core library.

Please refer to the documentationfor this

ngx.ocsp

Lua module for more details.

This feature requires at least ngx_lua

v0.10.0

.

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ndk.set_var.DIRECTIVE

syntax: res = ndk.setvar.DIRECTIVENAME

context: initworkerbylua*, setbylua*, rewritebylua*, accessbylua*, contentbylua*, headerfilterbylua*, bodyfilterbylua*, logbylua*, ngx.timer.*, balancerbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstorebylua*

This mechanism allows calling other Nginx C modules' directives that are implemented by Nginx Devel Kit (NDK)'s set_var submodule's ndk_set_var_value.

For example, the following set-misc-nginx-module directives can be invoked this way:

For instance,

local res = ndk.set\_var.set\_escape\_uri('a/b'); -- now res == 'a%2fb'

Similarly, the following directives provided by encrypted-session-nginx-module can be invoked from within Lua too:

This feature requires the ngx_devel_kit module.

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coroutine.create

syntax: co = coroutine.create(f)

context: rewritebylua*, accessbylua*, contentbylua*, initbylua*, ngx.timer.*, headerfilterbylua*, bodyfilterbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Creates a user Lua coroutines with a Lua function, and returns a coroutine object.

Similar to the standard Lua coroutine.create API, but works in the context of the Lua coroutines created by ngx_lua.

This API was first usable in the context of init_by_lua* since the

0.9.2

.

This API was first introduced in the

v0.6.0

release.

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coroutine.resume

syntax: ok, ... = coroutine.resume(co, ...)

context: rewritebylua*, accessbylua*, contentbylua*, initbylua*, ngx.timer.*, headerfilterbylua*, bodyfilterbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Resumes the executation of a user Lua coroutine object previously yielded or just created.

Similar to the standard Lua coroutine.resume API, but works in the context of the Lua coroutines created by ngx_lua.

This API was first usable in the context of init_by_lua* since the

0.9.2

.

This API was first introduced in the

v0.6.0

release.

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coroutine.yield

syntax: ... = coroutine.yield(...)

context: rewritebylua*, accessbylua*, contentbylua*, initbylua*, ngx.timer.*, headerfilterbylua*, bodyfilterbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Yields the execution of the current user Lua coroutine.

Similar to the standard Lua coroutine.yield API, but works in the context of the Lua coroutines created by ngx_lua.

This API was first usable in the context of init_by_lua* since the

0.9.2

.

This API was first introduced in the

v0.6.0

release.

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coroutine.wrap

syntax: co = coroutine.wrap(f)

context: rewritebylua*, accessbylua*, contentbylua*, initbylua*, ngx.timer.*, headerfilterbylua*, bodyfilterbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Similar to the standard Lua coroutine.wrap API, but works in the context of the Lua coroutines created by ngx_lua.

This API was first usable in the context of init_by_lua* since the

0.9.2

.

This API was first introduced in the

v0.6.0

release.

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coroutine.running

syntax: co = coroutine.running()

context: rewritebylua*, accessbylua*, contentbylua*, initbylua*, ngx.timer.*, headerfilterbylua*, bodyfilterbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Identical to the standard Lua coroutine.running API.

This API was first usable in the context of init_by_lua* since the

0.9.2

.

This API was first enabled in the

v0.6.0

release.

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coroutine.status

syntax: status = coroutine.status(co)

context: rewritebylua*, accessbylua*, contentbylua*, initbylua*, ngx.timer.*, headerfilterbylua*, bodyfilterbylua*, sslcertificatebylua*, sslsessionfetchbylua*, sslsessionstoreby_lua*

Identical to the standard Lua coroutine.status API.

This API was first usable in the context of init_by_lua* since the

0.9.2

.

This API was first enabled in the

v0.6.0

release.

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Obsolete Sections

This section is just holding obsolete documentation sections that have been either renamed or removed so that existing links over the web are still valid.

Back to TOC

Special PCRE Sequences

This section has been renamed to Special Escaping Sequences.

Back to TOC

Lua/LuaJIT bytecode support

This section has been renamed toLuaJIT bytecode support. As of version

v0.10.16

of this module, the standard Lua interpreter (also known as "PUC-Rio Lua") is not supported anymore.

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