nixos-version: output configurationRevision

[miallo]

It would be nice to be able to get the configurationRevision of the current system.

This allows the user to figure out more information about the generation.

Motivation for this change

It might also be used for #105910 to show additional information for generations in the list of all generations so that the user can have a better understanding of which generation is what.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable: => could not find relevant tests
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.05 Release Notes (or backporting 21.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[RaitoBezarius]

So sorry it did not get any attention, can you fix the conflicts? I'm interested into getting this merged.

[miallo]

So sorry it did not get any attention, can you fix the conflicts? I'm interested into getting this merged.

Absolutely no problem :) I rebased it and switched it from --configurationRevision to --configuration-revision, since that feels a lot better from my perspective

[RaitoBezarius]

LGTM.

[ncfavier]

This is kind of awful, but probably fine for now. I think nixos-version would make a good candidate for __structuredAttrs once #175649 lands in master.

[miallo]

I also did not particularly like it - I am happy to take a look into __structuredAttrs - should this included in this PR?

[ncfavier]

No, that's fine. __structuredAttrs wouldn't really help anyway since the structured attrs are only available at build time.

[miallo]

@RaitoBezarius @ncfavier Do you know who can merge this? Apart from commits by Eelco, the earliest thing apart from treewide shellcheck/shebang changes in this file are from 2016, so I don't really know who to ping...