wait-port

Simple binary to wait for a port to open. Useful when writing scripts which need to wait for a server to be availble, creating docker-compose commands which wait for servers to start and general server-side shenanigans. Can also wait for an HTTP endpoint to successfully respond.

• Installation
• Usage
  • Parameters
  • Error Codes
• API
• Developer Guide
  • Debugging
  • Testing
  • Testing the CLI
  • Manpage
  • Releasing
  • Timeouts

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
wait-port@0.1.3

$ ./node_modules/.bin/wait-port 8080
Waiting for localhost:8080.....
Connected!

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:

Error Codes

The following error codes are returned:

API

You can use wait-port programmatically:

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 params object takes the following parameters:

Developer Guide

This module uses:

| Name | Usage | | chalk | Terminal output styling. | | commander.js | Utility for building commandline apps. | | debug | Utility for debug output. | R mocha / nyc | Test runner / coverage. |

Debugging

This module use debug for debug output. Set DEBUG=wait-port to 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 debugger statement 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 link for 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.1 before publishing, as the format can be tricky to work with.

Releasing

Kick out a new release with:

npm version patch # or minor/major
git push --tags
npm publish

Timeouts

The timeout option for waitPort is 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 waitPort promise may take up to interval milliseconds greater than timeout to resolve.