anchor.diff:          type = types.nullOr types.str;
         };
   
  +      kubeconfig = mkKubeConfigOptions "Kubelet";
  +
         extraOpts = mkOption {
           description = "Kubernetes kubelet extra command line options.";
           default = "";
  
positive.code:       };
      };
  
      kubeconfig = {
        server = mkOption {
          description = "Kubernetes apiserver server address.";
          default = "http://${cfg.apiserver.address}:${toString cfg.apiserver.port}";
          type = types.str;
        };
  
        caFile = mkOption {
          description = "Certificate authrority file to use to connect to Kubernetes apiserver.";
          type = types.nullOr types.path;
          default = null;
        };
  
        certFile = mkOption {
          description = "Client certificate file to use to connect to Kubernetes.";
          type = types.nullOr types.path;
          default = null;
        };
  
        keyFile = mkOption {
          description = "Client key file to use to connect to Kubernetes.";
          type = types.nullOr types.path;
          default = null;
        };
      };
  
      dataDir = mkOption {
        description = "Kubernetes root directory for managing kubelet files.";
  
negative.code:         serviceConfig = {
            Slice = "kubernetes.slice";
            ExecStart = ''${pkgs.kube-dns}/bin/kube-dns \
              --kubecfg-file=${mkKubeConfig "kube-dns" cfg.dns.kubeconfig} \
              --dns-port=${toString cfg.dns.port} \
              --domain=${cfg.dns.domain} \
              ${optionalString cfg.verbose "--v=6"} \
  