Docker takes a conservative approach to cleaning up unused objects (often referred to as “garbage collection”), such as images, containers, volumes, and networks. These objects are generally not removed unless you explicitly ask Docker to do so. This can cause Docker to use extra disk space. For each type of object, Docker provides a
docker.comprunecommand.
docker image prune -fThis will prune (remove trash) only from your docker images, -f switch forces the command not to prompt for input, so it’s convenient to be used in crontab:
0 3 * * 0 docker image prune -fAt 03:00 on Sunday , do the docker image cleanup.