add support for multi-instances

[mrjk]

I'm proposing this PR to support multi-instances of nautilus-backup. I don't know if the implementation please you. So far, in other projects, there are two main way to accomplish this:

• Use a different label prefix
• Set a new option to filter only containers that match a key

I choose the first one, to avoid confusion since there is already an existing group option. This PR is complete, excepted tests are missing. I can eventually spend some time on writing them if you agree on the general implementation. Otherwise, feel free to make suggestions.

On my side, I'm already running nautical-backup with this patch on my infra, and it is working as expected.

[Minituff]

I like this @mrjk. Bonus points for updating the docs!!

I can see if I can get this merged in soon. Looks like I only need to update the formatting to get the tests to pass. I might add some unit tests as well.

Feel free to add that as well to speed up the process :)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.87%. Comparing base (eea99fd) to head (d6c7ebb).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #398      +/-   ##
==========================================
+ Coverage   90.83%   90.87%   +0.04%     
==========================================
  Files           9        9              
  Lines         884      888       +4     
==========================================
+ Hits          803      807       +4     
  Misses         81       81              

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[mrjk]

Ok, fixed the black issue.

I should really setup your project dev environment, but I'm not (yet) familiar with devcontainers, and last time I tried, setup was very slow, and seems to be stuck somewhere. Also, documentation is not totally clear on that topic. I'll try to update the doc when I'll have success with devcontainers ;)

About unit tests, I'm very bad at it, but I'll try to come with something tho; but I've quite limited time resources right now.