TL;DR use any/all of
docker system prune,
docker container prune,
docker image prune,
docker volume prune or
docker network prune to free the according space.
docker system df to look at the disk space used by docker, to see if it is worth it, or to be better informed.
I got this output:
> docker system df TYPE TOTAL ACTIVE SIZE RECLAIMABLE Images 125 12 15.27GB 15.03GB (98%) Containers 53 0 12.6GB 12.6GB (100%) Local Volumes 24 9 344.2MB 295.4MB (85%) Build Cache 169 0 5.8GB 5.8GB
Now that you know, you can free the memory with:
> docker system prune WARNING! This will remove: - all stopped containers - all networks not used by at least one container - all dangling images - all dangling build cache Are you sure you want to continue? [y/N] y Deleted Containers: 0b6aafd9ce1d346bec7470f6042b6e1b30516973e096ef1954ccd823f9bb846a ...
After that no containers to be removed anymore, proof:
> docker container prune WARNING! This will remove all stopped containers. Are you sure you want to continue? [y/N] y Total reclaimed space: 0B
docker image prune --all to gain a lot of disk space with the trade off of removing all your images, which will be downloaded when needed again.