docker wait-for-it
This code demonstrates an example implementation for one of Docker's recommended scripts to manage the startup order for containers, namely the wait-for-it Bash script. It is intended to be used to prevent dependent containers from starting up in a multi-container environment. The script will wait for a TCP connection attempt to succeed before running its command.
To execute the test, change directories to this codebase (/vagrant if using the Vagrantfile) and run the following command:
docker-compose upThis will build the example Docker image and run its "example" container alongside a MariaDB "db" container. The db container takes a few seconds to start and will not accept connections on port 3306 until it is fully ready. The "example" container will wait for "db" to be ready before executing its command. The command will exit with code 0 if it can connect to the database.
This same strategy may be used for web servers and other scenarios where immediate database connectivity is important.