nixos-servers/machines/default.nix

{
  nixpkgs,
  flake-utils,
  ...
}:
flake-utils.lib.eachDefaultSystem (system: let
  pkgs = nixpkgs.legacyPackages.${system};
  lib = pkgs.lib;

  machineOpts = {config, ...}: {
    options = {
      nixosModule = lib.mkOption {
        default = {...}: {};
        type = lib.types.anything;
        description = ''
          Customized configuration for this machine in the form of a NixOS module.
        '';
      };
    };
  };

  allOpts = {
    options = {
      machines = lib.mkOption {
        type = with lib.types; attrsOf (submodule machineOpts);
      };
    };
  };
in {
  machines =
    (lib.modules.evalModules {
      modules = [
        allOpts
        ./warwick
        ./atlas
        ./jefke
        ./lewis
        # ./talos.nix
      ];
    })
    .config
    .machines;
})