newsflash: fix adding xdg-open to PATH

[kira-bruneau]

Description of changes

Fixes opening links in newsflash

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• 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/)
• 22.11 Release Notes (or backporting 22.05 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
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[kira-bruneau]

Result of nixpkgs-review pr 186982 run on x86_64-linux 1

1 package built:

• newsflash

[LunNova]

Surprised you ran into this, many apps don't add this to the path/wrap it, and instead rely on environment.systemPackages having it from having a desktop environment enabled.

Adding it to the path from the package input like this makes it harder to swap out your implementation of xdg-utils/xdg-open at runtime as this package won't respect the version on the system path.

[kira-bruneau]

Yeah, I think something on my system was indirectly including xdg-open in my PATH before, so I didn't notice the problem before now.

A bunch of other apps in nixpkgs hard-code it too. Why would you need to swap out xdg-open at runtime? I think we should be hard-coding it whenever an application expects it to exist. It's basically just a proxy to whatever you have globally configured, in the same way dbus.lib is hard-coded for applications that use dbus.

[LunNova]

You might want to patch xdg-open to use the portal to launch apps without rebuilding everything that depends on it, or you might want to replace it entirely eg with handlr.

[kira-bruneau]

Ok thanks! That's a good point, I still feel like we should provide a default when you're not specifying a different implementation though. I noticed #181171 changes --prefix wrapper to --suffix wrappers in a bunch of places, would you be ok with that?

[LunNova]

Suffix sounds great! That's a cool PR.

[kira-bruneau]

I almost wonder if we should have someway to describe a package that depends on a something being in $PATH / requires a file to exist, without hardcoding a specific implementation.

Then something like nixos-rebuild should throw an error if you didn't add a package that satisfied the requirements.

[kira-bruneau]

I ended up making a discourse post about this kind of dependency:
https://discourse.nixos.org/t/should-we-support-encoding-runtime-dependencies-without-requiring-a-specific-implementation/21031

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/should-we-support-encoding-runtime-dependencies-without-requiring-a-specific-implementation/21031/6

[LunNova]

https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/services/x11/xserver.nix#L675 - this is the line adding it to the system path for most users and why nobody noticed this originally

[kira-bruneau]

Oh thanks for pointing that out!

[github-actions]

Successfully created backport PR #187396 for release-22.05.