A simple script that waits for a TCP socket to be accepting connections.

Add this to your Gemfile like any other gem:

gem 'wait-for-socket'

.. and then wait for a TCP socket, like MySQL:

bundle exec wait-for-socket --description MySQL --address 127.0.0.1 --port 3306
Waiting for MySQL to become available at 127.0.0.1:3306
....
MySQL ready

.. or postgres:

bundle exec wait-for-socket --description PostgreSQL --address 127.0.0.1 --port 5432
Waiting for PostgreSQL to become available at 127.0.0.1:5432
....
PostgreSQL ready

This is a pretty poor excuse for a rubygem - all it has is a single executable script.

It's bundled into a gem for ease of distriubtion. I've needed this functionality in many ruby applications (particularly in test suites running in docker), and this was the easiest way to share the script.