Docker - remove all but last N images

Question

I am trying to build a small script that removes all docker images besides a small "cache" of N last images (for rolling back to one of the last working versions).

Is there an idiomatic way to do this?

Answer 1

You can use the tail command to accomplish this.

Let's say you only want to keep the most recent 5 images. You can tell tail to show you the list starting with the nth line. For 5 images, you would want tail to start on the 6th line:

tail -n +6

Pair this with docker to show a list of your image IDs, which are sorted by most recent, by default.

docker images -q | tail -n +6

You can pass all of that to the remove images command. This assumes you're using the bash shell; if you use a csh-derived shell, you may need different syntax.

docker rmi $(docker images -q | tail -n +6)