{
  description = "Zentralwerk network";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs";
  };

  outputs = { self, nixpkgs }:
    let
      system = "x86_64-linux";
      systems = [ system ];
      forAllSystems = nixpkgs.lib.genAttrs systems;
    in
    rec {
      lib =
        import ./nix/lib { inherit nixpkgs; };

      packages = forAllSystems (system: {
        test_vm = nixpkgs.legacyPackages.${system}.runCommandLocal "test_vm" {
          src = nixosConfigurations.test_vm.config.system.build.toplevel;
        } ''
          set -x
          mkdir -p $out/{bin,dev,etc,home,mnt,nix/store,nix/var,proc,root,run,sys,tmp,var,usr}
          ln -s $src/init $out/
          ln -s $src/etc $out/etc/static
        '';
      } // (import ./nix/pkgs/device-templates.nix { inherit self nixpkgs system; }));

      nixosModule = { ... }: {
        imports = nixpkgs.lib.filesystem.listFilesRecursive ./nix/nixos-modules;
      };

      nixosConfigurations.test_vm =
        nixpkgs.lib.nixosSystem {
          inherit system;
          modules = [ nixosModule ];
          extraModules = [ ({ ... }: {
            networking.hostName = "test_vm";
          }) ];
        };

      nixosConfigurations.server1 =
        nixpkgs.lib.nixosSystem {
          inherit system;
          modules = [];
        };
    };
}