Factor out time zone and NTP

machine/backyard/default.nix

@@ -17,14 +17,6 @@
   # Enable networking
   networking.networkmanager.enable = true;
 
-  # Set your time zone.
-  time.timeZone = "UTC";
-
-  services.ntp = {
-    enable = true;
-    servers = [ "time.nist.gov" ];
-  };
-
   # Select internationalisation properties.
   i18n.defaultLocale = "en_US.UTF-8";
 

modules/beatific.nix

@@ -1,18 +1,34 @@
 { config, lib, pkgs, ... }:
 
 let
-  inherit (lib) mkOption types;
+  inherit (lib) mkIf mkMerge mkOption types;
   cfg = config.beatific;
 in {
   options = {
-    beatific.hostName = mkOption {
-      type = types.str;
-      description = "Hostname";
+    beatific = {
+      hostName = mkOption {
+        type = types.str;
+        description = "Hostname";
+      };
+
+      defaults = {
+        time = mkOption {
+          type = types.bool;
+          description = "Default time zone and NTP";
+          default = true;
+        };
+      };
     };
   };
 
-  config = let
-  in {
-    networking.hostName = cfg.hostName;
-  };
+  config = mkMerge [
+    {
+      networking.hostName = cfg.hostName;
+    }
+    (mkIf cfg.defaults.time {
+      time.timeZone = "UTC";
+      services.ntp.enable = true;
+      services.ntp.servers = [ "time.nist.gov" ];
+    })
+  ];
 }