General question about using disko when boostraping a system (flakes)

[Baitinq]

Hi, I had a general question about the usage of disko.

Currently, I am using disko in the inputs of my nixos configuration flake (https://github.com/baitinq/nixos-config) (example config in hosts/luna/disks.nix). It appears to work wonderfully, correctly creating the tsp-create/mount scripts on my system.

My question is the following, how would I use this when bootstrapping my nixos system on a new install? (which would be when it is really needed and useful).

I havent seen any flake related documentation on this, and I realise this might be a more personal nix problem with how my configuration is set up, but is there any way to just build a certain part of my configuration with flakes without having a new output created?

Thank you so much.

[Mic92]

I am not 100% sure I get your intention but you can build parts of your nixos system like this:

$ nix repl
Welcome to Nix 2.10.3. Type :? for he
nix-repl> :lf github:Mic92/dotfiles
nix-repl> :b nixosConfigurations.<PRESS_TAB> ...
nix-repl> :b nixosConfigurations.turingmachine.config.system.build.vm

# same as
$ nix build github:Mic92/dotfiles#nixosConfigurations.turingmachine.config.system.build.vm

This assumes that whatever is part of your nixos system is also exposed as an option.
If you want to build tsp-create from your nixos configuration you might need to expose it through a nixos module option:

{
  options.myoption = mkOption {                
     type = types.str;                                     
     default = tsp-create;
  };                                                      
}

$ nix build github:Mic92/dotfiles#nixosConfigurations.turingmachine.config.myoption

However it seems far easier to just expose it through a packages flake output and than just use.

nix run github:Mic92/dotfiles#tsp-create

Notice that when you use pkgs.callPackage you can reuse your partitioning script in both your nixos configuration and in packages.

I am going to close this issue, since it is not disko related. But you can continue to ask questions.

[Baitinq]

Thank you so much for your help, I'll definitely try your suggestion when I get access to my pc.

However it seems far easier to just expose it through a packages flake output and than just use.

Definitely, the problem is that I have three hosts and I wouldnt want to have to expose three different new outputs for each of their disko configurations. Do you know of any way to abstract this?

[Baitinq]

@Mic92 Right now Im trying to follow your option recommendation. This is it (currently a WIP) in case anyone wants to take a look in the future for documentation purposes. (Baitinq/nixos-config#2)

[Baitinq]

@Mic92 Im done with my implementation, maybe we should consider adding some documentation on how this would be achieved? @Lassulus (As it seems like it would be one of the main use cases for disko) For reference (https://github.com/Baitinq/nixos-config/blob/master/hosts/luna/disks.nix) (nix run .#nixosConfigurations.luna.config.disko-create) (nix run .#nixosConfigurations.luna.config.disko-mount)

[Mic92]

Yeah, looks a nice example.