{
  inputs,
  nixosModules,
  overlays,
  userdata,
  ...
}: {
  # Helper function for generating host configurations.
  mkHost = {
    hostname,
    system ? "x86_64-linux",
    extraArgs ? {},
    extraModules ? [],
  }: let
    inherit (inputs.nixpkgs) lib;
  in
    inputs.nixpkgs.lib.nixosSystem {
      inherit system;
      specialArgs =
        {inherit inputs userdata;}
        // extraArgs;

      modules =
        [
          {
            networking.hostName = lib.mkDefault hostname;
            nixpkgs.overlays = overlays;
          }
          ../machines/${hostname}
          nixosModules.default
          inputs.agenix.nixosModules.default
          inputs.disko.nixosModules.disko
          inputs.home-manager.nixosModules.home-manager
        ]
        ++ extraModules;
    };

  forAllSystems = inputs.nixpkgs.lib.genAttrs [
    "aarch64-linux"
    "i686-linux"
    "x86_64-linux"
    "aarch64-darwin"
    "x86_64-darwin"
  ];
}