nixos/headscale: remove much-loosened-up server_url check

[motiejus]

server_url check has been loosened upstream and backported to NixOS2. The new, much looser check, is not practical to be implemented in Nix (you are welcome to give it a try; I've implemented the original one).

Since the surface area is much smaller now (and the scenario much less common), I think we can remove this assertion altogether.

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/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 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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[motiejus]

Please follow the commit conventions https://github.com/NixOS/nixpkgs/blob/master/nixos/README.md#commit-conventions

Good call, thanks for the reminder. Updated!

[nixpkgs-ci]

Successfully created backport PR for release-24.11:

• [Backport release-24.11] nixos/headscale: remove much-loosened-up server_url check #374612

[dotlambda]

It would have been nice to ping me, since I originally added the assertion.

The new, much looser check, is not practical to be implemented in Nix

I think it wouldn't be hard at all. Should I try to? I remember it being very frustrated when headscale stopped working due to this check and I couldn't reach my server anymore but I guess the check has been in place long enough that nobody uses an unsupported configuration anymore.

[motiejus]

Sorry. It didn't occur to me toask, I would definitely do next time. :(

I "asked for changes" in the backporting patch, so we can at least stop the train somewhat? Hopefully that will stop landing.

In my opinion, I think the new, less restrictive config is much less common to be an issue, so is there still value?