let

  f =
    { stdenv, fetchurl, perl }:
      stdenv.mkDerivation {
       name = "hello-2.1.1";
       builder = ./builder.sh;
       src = fetchurl {
        url = ftp://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz;
        sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465";
       };
       inherit perl;
     };
in
{
  network.description = "KBAS";

  webserver =
    { config, pkgs, ... }:
    { services.httpd.enable = true;
      services.httpd.adminAddr = "[email protected]";
      services.httpd.documentRoot = "${pkgs.valgrind.doc}/share/doc/valgrind/html";
      networking.firewall.allowedTCPPorts = [ 80 ];
      environment.systemPackages = [ ???? ];
    };
}
~