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http-proxy-middleware

by chimurai

:zap: The one-liner node.js http-proxy middleware for connect, express and browser-sync

7.1K Stars 556 Forks Last release: about 2 months ago (v0.19.2) MIT License 264 Commits 43 Releases

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http-proxy-middleware

Build StatusCoverallsdependency Statusdependency Statuscode style: prettier

Node.js proxying made simple. Configure proxy middleware with ease for connect, express, browser-sync and many more.

Powered by the popular Nodejitsu [

http-proxy

](https://github.com/nodejitsu/node-http-proxy). GitHub stars

⚠️ Note

This page is showing documentation for version v1.x.x (release notes)

If you're looking for v0.x documentation. Go to: https://github.com/chimurai/http-proxy-middleware/tree/v0.21.0#readme

TL;DR

Proxy

/api

requests to

http://www.example.org
// javascript const express = require('express'); const { createProxyMiddleware } = require('http-proxy-middleware'); const app = express(); app.use('/api', createProxyMiddleware({ target: 'http://www.example.org', changeOrigin: true })); app.listen(3000); // http://localhost:3000/api/foo/bar -\> http://www.example.org/api/foo/bar
// typescript import \* as express from 'express'; import { createProxyMiddleware, Filter, Options, RequestHandler } from 'http-proxy-middleware'; const app = express(); app.use('/api', createProxyMiddleware({ target: 'http://www.example.org', changeOrigin: true })); app.listen(3000); // http://localhost:3000/api/foo/bar -\> http://www.example.org/api/foo/bar

All

http-proxy

options can be used, along with some extra

http-proxy-middleware

options.

:bulb: Tip: Set the option

changeOrigin

to

true

for name-based virtual hosted sites.

Table of Contents

$ npm install --save-dev http-proxy-middleware

Core concept

Proxy middleware configuration.

createProxyMiddleware([context,] config)

const { createProxyMiddleware } = require('http-proxy-middleware'); const apiProxy = createProxyMiddleware('/api', { target: 'http://www.example.org' }); // \_\_\_\_/ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_/ // | | // context options // 'apiProxy' is now ready to be used as middleware in a server.
  • context: Determine which requests should be proxied to the target host. (more on context matching)
  • options.target: target host to proxy to. (protocol + host)

(full list of [

http-proxy-middleware

configuration options](https://github.com/chimurai/http-proxy-middleware/blob/master/#options))

createProxyMiddleware(uri [, config])

// shorthand syntax for the example above: const apiProxy = createProxyMiddleware('http://www.example.org/api');

More about the shorthand configuration.

Example

An example with

express

server.

// include dependencies const express = require('express'); const { createProxyMiddleware } = require('http-proxy-middleware'); // proxy middleware options const options = { target: 'http://www.example.org', // target host changeOrigin: true, // needed for virtual hosted sites ws: true, // proxy websockets pathRewrite: { '^/api/old-path': '/api/new-path', // rewrite path '^/api/remove/path': '/path', // remove base path }, router: { // when request.headers.host == 'dev.localhost:3000', // override target 'http://www.example.org' to 'http://localhost:8000' 'dev.localhost:3000': 'http://localhost:8000', }, }; // create the proxy (without context) const exampleProxy = createProxyMiddleware(options); // mount `exampleProxy` in web server const app = express(); app.use('/api', exampleProxy); app.listen(3000);

Context matching

Providing an alternative way to decide which requests should be proxied; In case you are not able to use the server's [

path

parameter](http://expressjs.com/en/4x/api.html#app.use) to mount the proxy or when you need more flexibility.

[RFC 3986

path

](https://tools.ietf.org/html/rfc3986#section-3.3) is used for context matching.

foo://example.com:8042/over/there?name=ferret#nose \_/ \_\_\_\_\_\_\_\_\_\_\_\_\_\_/\_\_\_\_\_\_\_\_\_/ \_\_\_\_\_\_\_\_\_/ \_\_/ | | | | | scheme authority path query fragment
  • path matching*

    • createProxyMiddleware({...})
      • matches any path, all requests will be proxied.
    • createProxyMiddleware('/', {...})
      • matches any path, all requests will be proxied.
    • createProxyMiddleware('/api', {...})
      • matches paths starting with
        /api

multiple path matching

  • createProxyMiddleware(['/api', '/ajax', '/someotherpath'], {...})
    • wildcard path matching

For fine-grained control you can use wildcard matching. Glob pattern matching is done by micromatch. Visit micromatch or glob for more globbing examples.

  • createProxyMiddleware('\*\*', {...})
    matches any path, all requests will be proxied.
  • createProxyMiddleware('\*\*/\*.html', {...})
    matches any path which ends with
    .html
  • createProxyMiddleware('/\*.html', {...})
    matches paths directly under path-absolute
  • createProxyMiddleware('/api/\*\*/\*.html', {...})
    matches requests ending with
    .html
    in the path of
    /api
  • createProxyMiddleware(['/api/\*\*', '/ajax/\*\*'], {...})
    combine multiple patterns
  • createProxyMiddleware(['/api/\*\*', '!\*\*/bad.json'], {...})
    exclusion

Note: In multiple path matching, you cannot use string paths and wildcard paths together.

  • custom matching

For full control you can provide a custom function to determine which requests should be proxied or not.

/\*\* \* @return {Boolean} \*/ const filter = function (pathname, req) { return pathname.match('^/api') && req.method === 'GET'; }; const apiProxy = createProxyMiddleware(filter, { target: 'http://www.example.org', });

Options

http-proxy-middleware options

  • option.pathRewrite: object/function, rewrite target's url path. Object-keys will be used as RegExp to match paths.
// rewrite path pathRewrite: {'^/old/api' : '/new/api'} // remove path pathRewrite: {'^/remove/api' : ''} // add base path pathRewrite: {'^/' : '/basepath/'} // custom rewriting pathRewrite: function (path, req) { return path.replace('/api', '/base/api') } // custom rewriting, returning Promise pathRewrite: async function (path, req) { const should\_add\_something = await httpRequestToDecideSomething(path); if (should\_add\_something) path += "something"; return path; }
  • option.router: object/function, re-target
    option.target
    for specific requests.
// Use `host` and/or `path` to match requests. First match will be used. // The order of the configuration matters. router: { 'integration.localhost:3000' : 'http://localhost:8001', // host only 'staging.localhost:3000' : 'http://localhost:8002', // host only 'localhost:3000/api' : 'http://localhost:8003', // host + path '/rest' : 'http://localhost:8004' // path only } // Custom router function (string target) router: function(req) { return 'http://localhost:8004'; } // Custom router function (target object) router: function(req) { return { protocol: 'https:', // The : is required host: 'localhost', port: 8004 }; } // Asynchronous router function which returns promise router: async function(req) { const url = await doSomeIO(); return url; }
  • option.logLevel*: string, ['debug', 'info', 'warn', 'error', 'silent']. Default:

'info'
  • option.logProvider*: function, modify or replace log provider. Default:

console

.

// simple replace function logProvider(provider) { // replace the default console log provider. return require('winston'); }
// verbose replacement function logProvider(provider) { const logger = new (require('winston').Logger)(); const myCustomProvider = { log: logger.log, debug: logger.debug, info: logger.info, warn: logger.warn, error: logger.error, }; return myCustomProvider; }

http-proxy events

Subscribe to http-proxy events:

  • option.onError: function, subscribe to http-proxy's
    error
    event for custom error handling.
function onError(err, req, res) { res.writeHead(500, { 'Content-Type': 'text/plain', }); res.end('Something went wrong. And we are reporting a custom error message.'); }
  • option.onProxyRes: function, subscribe to http-proxy's
    proxyRes
    event.
function onProxyRes(proxyRes, req, res) { proxyRes.headers['x-added'] = 'foobar'; // add new header to response delete proxyRes.headers['x-removed']; // remove header from response }
  • option.onProxyReq: function, subscribe to http-proxy's
    proxyReq
    event.
function onProxyReq(proxyReq, req, res) { // add custom header to request proxyReq.setHeader('x-added', 'foobar'); // or log the req }
  • option.onProxyReqWs: function, subscribe to http-proxy's
    proxyReqWs
    event.
function onProxyReqWs(proxyReq, req, socket, options, head) { // add custom header proxyReq.setHeader('X-Special-Proxy-Header', 'foobar'); }
  • option.onOpen: function, subscribe to http-proxy's
    open
    event.
function onOpen(proxySocket) { // listen for messages coming FROM the target here proxySocket.on('data', hybiParseAndLogMessage); }
  • option.onClose: function, subscribe to http-proxy's
    close
    event.
function onClose(res, socket, head) { // view disconnected websocket connections console.log('Client disconnected'); }

http-proxy options

The following options are provided by the underlying http-proxy library.

  • option.target: url string to be parsed with the url module
  • option.forward: url string to be parsed with the url module
  • option.agent: object to be passed to http(s).request (see Node's https agent and http agent objects)
  • option.ssl: object to be passed to https.createServer()
  • option.ws: true/false: if you want to proxy websockets
  • option.xfwd: true/false, adds x-forward headers
  • option.secure: true/false, if you want to verify the SSL Certs
  • option.toProxy: true/false, passes the absolute URL as the
    path
    (useful for proxying to proxies)
  • option.prependPath: true/false, Default: true - specify whether you want to prepend the target's path to the proxy path
  • option.ignorePath: true/false, Default: false - specify whether you want to ignore the proxy path of the incoming request (note: you will have to append / manually if required).
  • option.localAddress : Local interface string to bind for outgoing connections
  • option.changeOrigin: true/false, Default: false - changes the origin of the host header to the target URL
  • option.preserveHeaderKeyCase: true/false, Default: false - specify whether you want to keep letter case of response header key
  • option.auth : Basic authentication i.e. 'user:password' to compute an Authorization header.
  • option.hostRewrite: rewrites the location hostname on (301/302/307/308) redirects.
  • option.autoRewrite: rewrites the location host/port on (301/302/307/308) redirects based on requested host/port. Default: false.
  • option.protocolRewrite: rewrites the location protocol on (301/302/307/308) redirects to 'http' or 'https'. Default: null.
  • option.cookieDomainRewrite: rewrites domain of
    set-cookie

    headers. Possible values:

    false
    (default): disable cookie rewriting
    • String: new domain, for example
      cookieDomainRewrite: "new.domain"
      . To remove the domain, use
      cookieDomainRewrite: ""
      .
    • Object: mapping of domains to new domains, use
      "\*"
      to match all domains.
      For example keep one domain unchanged, rewrite one domain and remove other domains:
      json cookieDomainRewrite: { "unchanged.domain": "unchanged.domain", "old.domain": "new.domain", "\*": "" }
  • option.cookiePathRewrite: rewrites path of
    set-cookie

    headers. Possible values:

    false
    (default): disable cookie rewriting
    • String: new path, for example
      cookiePathRewrite: "/newPath/"
      . To remove the path, use
      cookiePathRewrite: ""
      . To set path to root use
      cookiePathRewrite: "/"
      .
    • Object: mapping of paths to new paths, use
      "\*"
      to match all paths. For example, to keep one path unchanged, rewrite one path and remove other paths:
      json cookiePathRewrite: { "/unchanged.path/": "/unchanged.path/", "/old.path/": "/new.path/", "\*": "" }
  • option.headers: object, adds request headers. (Example:
    {host:'www.example.org'}
    )
  • option.proxyTimeout: timeout (in millis) when proxy receives no response from target
  • option.timeout: timeout (in millis) for incoming requests
  • option.followRedirects: true/false, Default: false - specify whether you want to follow redirects
  • option.selfHandleResponse true/false, if set to true, none of the webOutgoing passes are called and it's your responsibility to appropriately return the response by listening and acting on the
    proxyRes
    event
  • option.buffer: stream of data to send as the request body. Maybe you have some middleware that consumes the request stream before proxying it on e.g. If you read the body of a request into a field called 'req.rawbody' you could restream this field in the buffer option:
'use strict'; const streamify = require('stream-array'); const HttpProxy = require('http-proxy'); const proxy = new HttpProxy(); module.exports = (req, res, next) =\> { proxy.web( req, res, { target: 'http://localhost:4003/', buffer: streamify(req.rawBody), }, next ); };

Shorthand

Use the shorthand syntax when verbose configuration is not needed. The

context

and

option.target

will be automatically configured when shorthand is used. Options can still be used if needed.

createProxyMiddleware('http://www.example.org:8000/api'); // createProxyMiddleware('/api', {target: 'http://www.example.org:8000'}); createProxyMiddleware('http://www.example.org:8000/api/books/\*/\*\*.json'); // createProxyMiddleware('/api/books/\*/\*\*.json', {target: 'http://www.example.org:8000'}); createProxyMiddleware('http://www.example.org:8000/api', { changeOrigin: true }); // createProxyMiddleware('/api', {target: 'http://www.example.org:8000', changeOrigin: true});

app.use(path, proxy)

If you want to use the server's

app.use
path

parameter to match requests; Create and mount the proxy without the http-proxy-middleware

context

parameter:

app.use('/api', createProxyMiddleware({ target: 'http://www.example.org', changeOrigin: true }));
app.use

documentation:

WebSocket

// verbose api createProxyMiddleware('/', { target: 'http://echo.websocket.org', ws: true }); // shorthand createProxyMiddleware('http://echo.websocket.org', { ws: true }); // shorter shorthand createProxyMiddleware('ws://echo.websocket.org');

External WebSocket upgrade

In the previous WebSocket examples, http-proxy-middleware relies on a initial http request in order to listen to the http

upgrade

event. If you need to proxy WebSockets without the initial http request, you can subscribe to the server's http

upgrade

event manually.

const wsProxy = createProxyMiddleware('ws://echo.websocket.org', { changeOrigin: true }); const app = express(); app.use(wsProxy); const server = app.listen(3000); server.on('upgrade', wsProxy.upgrade); // 
## Working examples

View and play around with [working examples](https://github.com/chimurai/http-proxy-middleware/tree/master/examples).

Recipes

View the recipes for common use cases.

Compatible servers

http-proxy-middleware

is compatible with the following servers:

Sample implementations can be found in the server recipes.

Tests

Run the test suite:

# install dependencies $ yarn # linting $ yarn lint $ yarn lint:fix # building (compile typescript to js) $ yarn build # unit tests $ yarn test # code coverage $ yarn cover

Changelog

License

The MIT License (MIT)

Copyright (c) 2015-2020 Steven Chim

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