Hydra is still using old `nix flake info` command

[AmandaCameron]

With the latest nixos-unstable nixFlakes package, flakes won't work in hydra due to nix flake info being removed.

The evaluation error says:

'nix flake info' returned exit code 1:
warning: unknown setting 'gc-check-reachability'
error: 'info' is not a recognised command
Try '/nix/store/rws148paj539g0si9jmdi59smj9bdwqs-nix-2.4pre20210317_8a5203d/bin/nix --help' for more information.

This looks like the code that needs updating, but I'm not sure if it's been wormed into other places in the code as well.

Worth noting that it seems nixpkgs master may have bumped up to a version which re-introduced nix flake info, but it's worth getting hydra using the right command either way.

[grahamc]

Looks like we should use nix flake metadata instead.

[ethancedwards8]

Yes. This should be an easy enough fix.

[JackKelly-Bellroy]

Should this be closed? https://github.com/NixOS/hydra/commit/b16470c54434966b227de93c5229811c9c2afab4 made hydra-eval-jobset call nix flake metadata.

[isubasinghe]

I am still running into this for some reason. I am using nixos 23.05 as well.

https://github.com/isubasinghe/nixos-config/blob/main/nixos/configuration.nix#L139