nix: Package zerofs in nix, add nixos module, and nixos tests

[hinshun]

Hi @Barre, not sure if there's appetite to have Nix support but I'd like to use ZeroFS in my NixOS fleet. I packaged zerofs in Nix, added NixOS modules which provides the systemd services for NixOS and I've also added integration tests using NixOS's qemu VM test harness that you can run locally and even breakpoint inside with machine.shell_interact().

Perhaps it's an improvement over the integration tests you're maintaining in github actions atm. See how they're used here in nix-snapshotter: https://github.com/pdtpartners/nix-snapshotter/blob/ce7698e34990e1e59b9693e5c8ec08f4d9bf2fb6/.github/workflows/ci.yml#L40 and https://github.com/pdtpartners/nix-snapshotter/tree/main/modules/nixos/tests.

If you have nix installed, you can run the tests with: nix run .#test-nfs, nix run .#test-nbd-zfs, etc. You could also get caching via cachix, etc.

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[Barre]

Hi,

Thank you for the contribution!

Hi @Barre, not sure if there's appetite to have Nix support but I'd like to use ZeroFS in my NixOS fleet.

I'd like to have such support, I am not a Nix user myself, so I'll need a bit of time to review this properly.

[dcdq]

This is fantastic, thank you. Would definitely urge adopting more nix on top of this pr for zerofs development and cicd.

[lblasc]

Great to see more Nix users interested in zerofs! I’m maintaining the zerofs package in nixpkgs.

It would be useful to me if you could add NixOS modules to nixpkgs - currently, there are none.
Also integration tests (if not accepted to upstream) I think it could be usefully to have them in nixpkgs.

[randybias]

+1. I'm not using Nix yet, but I'm eyeballing it pretty hard.