Fix for https://github.com/NixOS/nixpkgs/pull/258680

[e-nikolov]

Fix for NixOS/nixpkgs#258680

network-online.target must now be explicitly depended on

[danderson]

We shouldn't need to depend on network-online.target at all, that's an antipattern in systemd that slows down boot. tsnet gracefully adapts to network changes on the fly, so it's completely fine to start concurrently with network bringup. I would actually argue for removing the after constraint, rather than adding require.

What problem does this ordering constraint fix? We should fix golink if it doesn't work correctly without this dependency.

[e-nikolov]

I took the safer bet of requiring it because I wasn't sure. Currently golink fails to build on the latest nixpkgs because of the linked PR. I get this error:

error:
       … while checking flake output 'nixosConfigurations'

       … while checking the NixOS configuration 'nixosConfigurations.home-nix'

       … while calling the 'head' builtin

         at /nix/store/kwd6lmx004rkv2r00vj3fcg5ijfvnagk-source/lib/attrsets.nix:960:11:

          959|         || pred here (elemAt values 1) (head values) then
          960|           head values
             |           ^
          961|         else

       (stack trace truncated; use '--show-trace' to show the full trace)

       error:
       Failed assertions:
       - golink.service is ordered after 'network-online.target' but doesn't depend on it
Error: Process completed with exit code 1.

[danderson]

That... is a weird failure for a different reason, after without wants is a completely legal configuration (ordering constraint on an optional dependency, "if this target is in the boot closure, here's an ordering, but I don't need it"), it's very weird that nixos rejects it.

Let's add the dependency for now to unblock the build, but really we should remove this dependency completely in the longer run. Letting CI run now and I will merge when it passes, thanks!

[e-nikolov]

I think they added it as a check when they made "multi-user.target" to no longer depend on "network-online.target" because a lot of existing services depended on that behavior.

[danderson]

Yeah, fair enough. Ordering without requiring is unusual, especially for network-online.target.