nixos-anywhere: Install jq when using --no-disko-deps

[hgl]

This is a different way of fixing nix-community/disko#1091

Nixos-anywhere will run commands like:

jq -r -f /nix/store/fpwn44vygjj6bfn8s1jj9p8yh6jhfxni-disk-deactivate/zfs-swap-deactivate.jq
...
jq -r --arg disk_to_clear /dev/sda -f /nix/store/fpwn44vygjj6bfn8s1jj9p8yh6jhfxni-disk-deactivate/disk-deactivate.jq

During installation, and with --no-disko-deps, jq isn't available on the official nixos-installer, and these command can fail.

[Mic92]

--no-disko-deps means the user is responsible for using an installer that has all the tools necessary installed. The machine in question might not have internet or not enough memory to download a nixpkgs channel. For example it breaks our NixOS test this way.

[Mic92]

We also provide https://github.com/nix-community/nixos-images?tab=readme-ov-file where jq is available for booting from USB or you just don't pass this flag.

[hgl]

Thanks for the tip.

In my case, the remote machine is in a cloud environment that

1. Has very limited amount of ram
2. Can only mount predetermined official nixos iso

Which requires --no-disko-deps.

I sent the PR because it seems the official installer already contains every tool needed by nixos-anywhere, except for jq, and I assumed if jq could be added, we could use --no-disko-deps transparently at least with the official installer, but maybe this isn't true?

I'm writing a downstream tool that uses nixos-anywhere to install nixos to remote machines, and I hoped to make the official installer a first class citizen where even if the ram is limited, nixos could still be successfully installed without user intervention. I wonder if this goal is feasible?

If the design goal is that no deps disko should not trigger network download, which makes sense, then maybe it's not?

I've fixed the build error though.

[Mic92]

Could you check if jq is included in the nixos installer closure? Maybe we can just expose jq in the NixOS image.

[Mic92]

Found one candidate: https://github.com/NixOS/nixpkgs/blob/94def634a20494ee057c76998843c015909d6311/pkgs/by-name/ni/nixos-option/package.nix#L50

[Enzime]

We could add jq as a default package possibly https://github.com/NixOS/nixpkgs/blob/531ef345f82f4fcaf04646b961963ed69f9c1f09/nixos/modules/config/system-path.nix

[Mic92]

It's actually always in the installer: https://github.com/NixOS/nixpkgs/blob/531ef345f82f4fcaf04646b961963ed69f9c1f09/nixos/modules/profiles/installation-device.nix#L115

Are you sure you are using the official nixos installer? If you are using a nix installer it should be easy to just include additional lines to install missing tools.

[Mic92]

Ah maybe extraDependencies doesn't get propageted into the $PATH. But in that case we might as well just include it environment.systemPackages as well.

[hgl]

Yep, it's not in the PATH, but is in the store already, confirmed with the 24.11 image.

[Mic92]

Okay, than please open a pull request in nixpkgs and link it here.

[hgl]

NixOS/nixpkgs#429759

[hgl]

PR has been merged.