dwmkerr/ wait-port
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MIT License 
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Description
Simple binary to wait for a port to open. Useful for docker-compose and general server side activities.
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wait-port
Simple binary to wait for a port to open. Useful when writing scripts which need to wait for a server to be available. - Creating
docker-composecommands which wait for servers to start - Wait for an HTTP endpoint to successfully respond - Wait for DNS records to be resolvable - Wait for application servers to start
Installation
Install globally with
npm:
$ npm install -g wait-port
If installing locally, run the binary from the local node modules binary folder:
$ npm install wait-port [email protected]$ ./node_modules/.bin/wait-port 8080 Waiting for localhost:8080..... Connected!
Requires Node 8 or later.
Usage
To wait indefinitely for a port to open, just use:
$ wait-port localhost:3000
To wait for a port to open, but limit to a certain timeout, use:
$ wait-port -t 10000 localhost:3000
To wait for an HTTP endpoint to respond with a 200 class status code, include the
http://protocol:
$ wait-port http://:3000/healthcheck
Parameters
The following parameters are accepted:
| Parameter | Usage | |-----------|-------| |
| Required. The target to test for. Can be just a port, a colon and port (as one would use with httpie or host and port. Examples:8080,
:3000,
127.0.0.1:443. | |
--output, -o| Optional. Output style to use. Can be
dots(default) or
silent(no output). | |
--timeout, -t| Optional. Timeout (in milliseconds). | |
--wait-for-dns| Optional. Do not error if the response is
ENOTFOUND, just keep on waiting (useful if you are waiting for a DNS record to also be created). |
Error Codes
The following error codes are returned:
| Code | Meaning | |------|---------| |
0| The specified port on the host is accepting connections. | |
1| A timeout occurred waiting for the port to open. | |
2| An unknown error occurred waiting for the port to open. The program cannot establish whether the port is open or not. | |
3| The address cannot be found (e.g. no DNS entry, or unresolvable). | |
4| The target (host and port) is invalid. |
API
You can use
wait-portprogrammatically:
const waitPort = require('wait-port');
const params = {
host: 'google.com',
port: 443,
};
waitPort(params)
.then((open) => {
if (open) console.log('The port is now open!');
else console.log('The port did not open before the timeout...');
})
.catch((err) => {
console.err(An unknown error occured while waiting for the port: ${err});
});
The CLI is a very shallow wrapper around this function. The
paramsobject takes the following parameters:
| CLI Parameter | API Parameter | Notes | |---------------|---------------|-------| |
|host| Optional. Defaults to
localhost. | | |
port| Required. Port to wait for. | |
--output|
output| Optional. Defaults to
dots. Output style to use.
silentalso accepted. | |
--timeout, -t|
timeout| Optional. Defaults to
0. Timeout (in milliseconds). If
0, then the operation will never timeout. | |
--wait-for-dns|
waitForDns| Optional. Defaults to
false. |
Developer Guide
This module uses:
| Name | Usage | |------------------------------------------------------------------------------|----------------------------------------| |
chalk| Terminal output styling. | |
commander.js| Utility for building commandline apps. | |
debug| Utility for debug output. | |
mocha/
nyc| Test runner / coverage. |
Debugging
debugfor debug output. Set
DEBUG=wait-portto see detailed diagnostic information:
DEBUG=wait-port wait-for -t 10000 localhost:6234
This will also work for any code which uses the API.
Testing
Run unit tests with
npm test. Coverage is reported to
artifacts/coverage.
Debug unit tests with
npm run debug. Add a
debuggerstatement to the line you are interested in, and consider limiting scope with
.only.
Run tests continuously, watching source with
npm run test:watch.
Testing the CLI
Don't install the package to test the CLI. Instead, in the project folder run
npm link. Now go to whatever folder you want to use the module in and run
npm link wait-port. It will symlink the package and binary. See
npm linkfor more details.
Manpage
Installing the CLI will install the manpage. The manpage is at
./man/wait-port.1. After updating the page, test it with
man ./man/wait-port.1before publishing, as the format can be tricky to work with.
Releasing
Kick out a new release with:
npm run release git push --follow-tags npm publish
standard-versionis used to manage version numbers and the
CHANGELOG.mdfile.
CI/CD
CI runs on CircleCI 2. You can validate the Circle configuration with the following command:
make circleci
Timeouts
The timeout option for
waitPortis used terminate attempts to open the socket after a certain amount of time has passed. Please note that operations can take significantly longer than the timeout. For example:
const promise = waitPort({ port: 9000, interval: 10000 }, 2000);
In this case, the socket will only attempt to connect every ten seconds. So on the first iteration, the timeout is not reached, then another iteration will be scheduled for after ten seconds, meaning the timeout will happen eight seconds later than one might expect.
The
waitPortpromise may take up to
intervalmilliseconds greater than
timeoutto resolve.