A better way for deleting Docker images and containers

In one of my last posts, I described the current (sad) state of managing Docker container and image expiration. Briefly, Docker creates new containers and images for many tasks, but there is no good way to automatically remove them. The best practice seems to be a rather hack-ish bash one-liner.

Since this wasn't particularly satisfying, I decided to do something about it. Here, I present docker-cleanup, a Python application for removing containers and images based on a configurable set of rules.

This is a rules file example:

# Keep currently running containers, delete others if they last finished
# more than a week ago.
KEEP CONTAINER IF Container.State.Running;
DELETE CONTAINER IF Container.State.FinishedAt.before('1 week ago');

# Delete dangling (unnamed and not used by containers) images.
DELETE IMAGE IF Image.Dangling;

Clear, expressive, straight-forward. The rule language can do a whole lot more and provides a readable and intuitive way to define removal policies for images and containers.

Head over to GitHub, give it a try, and let me know what you think!