Feature Request: tag old image for easy rollback, prune later

[chatziko]

Hi all and thanks for this awesome tool!

I currently use the -p flag to auto prune images, cause nobody wants to pile old stuff over time. It works well with just one major drawback:

Occasionally an upgrade might severely break some functionalty. A good response is to quickly releauch the old container to restore functionality, then investigate. But with -p the previous image is pruned, so I need to figure out what exactly version was running before the update, which is not always easy. And even if I manage to find it, I have to re-pull it, which delays the fix (and it's not even guaranteed that the previous image still exists in the repository).

So I propose something along the following lines:

• dockcheck, instead of pruning old images, it tags them with a clear tag, say dockcheck-update-2025-01-01_10:32.
• now if I want to rollback it's very easy, I'll just select the tag I want.
• then future updates can prune the image based on the tag timestamp, say after one week or something.

I think it's a simple and clean idea that could be useful to a lot of users.