anchor.diff:        serviceConfig = {
           Type = "simple";
           PermissionsStartOnly = true;
  -        ExecStart = "${pkgs.varnish}/sbin/varnishd -a ${cfg.http_address} -f ${pkgs.writeText "default.vcl" cfg.config} -n ${cfg.stateDir} -F ${cfg.extraCommandLine}"
  -          + optionalString (cfg.extraModules != []) " -p vmod_path='${makeSearchPathOutput "lib" "lib/varnish/vmods" ([pkgs.varnish] ++ cfg.extraModules)}' -r vmod_path";
  +        ExecStart = "${pkgs.varnish}/sbin/varnishd -a ${cfg.http_address} -n ${cfg.stateDir} -F ${cfg.extraCommandLine} ${commandLine}";
           Restart = "always";
           RestartSec = "5s";
           User = "varnish";
  
positive.code: 
      environment.systemPackages = [ pkgs.varnish ];
  
      users.extraUsers.varnish = {
        group = "varnish";
        uid = config.ids.uids.varnish;
  
negative.code: { config, lib, pkgs, ...}:
  
  with lib;
  
  let
    cfg = config.services.varnish;
  
    commandLine = "-f ${pkgs.writeText "default.vcl" cfg.config}" +
        optionalString (cfg.extraModules != []) " -p vmod_path='${makeSearchPathOutput "lib" "lib/varnish/vmods" ([pkgs.varnish] ++ cfg.extraModules)}' -r vmod_path";
  in
  {
    options = {
      services.varnish = {
  