What does it do?
This will provide composer. It is mainly used as a building block for other containers, but you can use this to install or run composer tasks from the container.
The Sources
Docker: https://hub.docker.com/r/willhallonline/composer/ GitHub: https://github.com/willhallonline/docker-composer
Commands
Commands you can run to use this.
Aliases
Aliases you can use from the Docker DevTools aliases.
phpcs-drupal="docker_alias /app willhallonline/composer:alpine phpcs"
phpcbf-drupal="docker_alias /app willhallonline/composer:alpine phpcbf"
Container
docker pull willhallonline/composer:alpine
OR (if you want based on Debian rather than Alpine)
docker pull willhallonline/composer