Add "docker image prune" query for moving Container Manager

[Dennis90BW]

Hello Dave,

nice work! very handy script. Maybe you could add a query to clean-up docker images before stopping the Container Manager and start a backup. My backup takes ages because of millions of unnecessary docker subvolume files in the @docker directory. The docker image prune command should do the job. (See: https://docs.docker.com/reference/cli/docker/image/prune/)

[007revad]

Interesting.

My Synology_docker_cleanup script uses the following to delete dangling images:

docker rmi "$(docker images -f "dangling=true" -q)"

but it looks like I could have just used:

docker image prune

On my test Synology I had 5 images and 3 containers and ran docker image prune --all

# docker image prune --all
WARNING! This will remove all images without at least one container associated to them.
Are you sure you want to continue? [y/N] y
Deleted Images:
deleted:
deleted:
deleted:
deleted:
deleted:
deleted:

Total reclaimed space: 0B

It appears to have deleted 6 images, but didn't show which images. I assume 4 of those were dangling images. The 2 unused images totalled 64MB so I'm not sure why it says Total reclaimed space: 0B

I think I'll use docker image prune in the script to just delete dangling images.

[007revad]

I've added "docker image prune" in v3.2.61

https://github.com/007revad/Synology_app_mover/releases/tag/v3.2.61