nixos/keycloak: add realmFiles option

[rorosen]

Description of changes

Enable realm imports during startup as described in the corresponding Keycloak guide.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • 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/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 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
• Fits CONTRIBUTING.md.

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[onny]

This is a nice feature, could you rebase the PR to resolve the merge conflict?

[rorosen]

Sorry, I lost track of it. The merge conflict is resolved now.

[onny]

tested and works for me 👍 really usefull

[onny]

[onny]

We could also add a note to the 24.11 release notes about this new feature :)

[onny]

Just thought about managing the realm files in /run/keycloak/... via systemd.tmpfiles? so if we remove one from the realmFiles option, it gets removed from the /run-directory too

[onny]

For example

systemd.tmpfiles.rules = [
  "L+ /run/keycloak/data/import/myrealm.json - - - - "${pkgs.writeText "myrealm.json" builtins.toJSON realmJSON}"
];

[rorosen]

I tested this but the links also don't get removed during rebuild when using systemd.tmpfiles. I don't see how systemd would clean up links, except we set an age. However, I'm very fine with using systemd.tmpfiles anyway instead of installing the realm files.

[rorosen]

I rebased to resolve conflicts and it uses tmpfiles to link the realm files now.

[onny]

Looks nice, I'll give it a try! Would you mind adding a note to the 25.05 release notes?

[rorosen]

Would you mind adding a note to the 25.05 release notes?

Done

[frederictobiasc]

LGTM. Would be nice if we could get this merged.

[onny]

Thank you!