{
  network.description = "My first NixOS cluster";
  network.enableRollback = true;

  nixos-01 = {config, pkgs,...}:
  {
    imports = [ ./config-extra.nix ];
    environment.systemPackages = with pkgs; [mc];
    deployment.targetHost = "nixos-01";
  };

  nixos-02 = {
    imports = [ ./config-extra.nix ];
    deployment.targetHost = "nixos-02";
  };

  nixos-03 = {
    imports = [ ./config-extra.nix ];
    deployment.targetHost = "nixos-03";
  };
}