Allow specifying the timezone

lib/modules/valhalla.nix

@@ -1,6 +1,22 @@
-{ ... }: {
+{ lib, ... }:
+  let
+    inherit (lib)
+      mkOption
+      types
+    ;
+  in {
     imports = [
       ./i18n.nix
       ./partition.nix
     ];
+
+    options = {
+      valhalla = {
+        timeZone = mkOption {
+          type = types.nullOr types.str;
+          description = "The time zone of the system.";
+          default = null;
+        };
+      };
+    };
   }

profiles/Generic/config.nix

@@ -34,6 +34,8 @@
           };
         };
 
+        timeZone = "Europe/Zurich";
+
         i18n = {
           localeSettings =
             let defaultLocale = "en_US.UTF-8";

scripts/Arch/OS/setup.fish

@@ -5,7 +5,6 @@ begin
     source "$dir/../../Common/Scripts/hooks.fish"
 
     set -q CONFIG_MODULE || set -l CONFIG_MODULE "$dir/config.nix"
-    set -q ARCH_TIMEZONE || set -l ARCH_TIMEZONE "Europe/Zurich"
     set -q ARCH_LANG || set -l ARCH_LANG en_US.UTF-8
     set -q ARCH_KEYMAP || set -l ARCH_KEYMAP de_CH-latin1
     set -q ARCH_X11_KEYMAP || set -l ARCH_X11_KEYMAP ch
@@ -23,7 +22,10 @@ begin
         set -l tempDir "$tempRoot/$relativeDir"
 
         loadkeys "$ARCH_KEYMAP"
-        and timedatectl set-timezone "$ARCH_TIMEZONE"
+
+        and if set -l timezone (getConfig valhalla.timeZone)
+            timedatectl set-timezone "$timezone"
+        end
 
         and CONFIG_MODULE=$CONFIG_MODULE bash "$dir/../../Common/OS/partition.sh"
 
@@ -46,7 +48,10 @@ begin
 
         and arch-chroot "$mountDir" systemctl enable NetworkManager
 
-        and arch-chroot "$mountDir" ln -sf "/usr/share/zoneinfo/$ARCH_TIMEZONE" /etc/localtime
+        and if set -q timezone
+            arch-chroot "$mountDir" ln -sf "/usr/share/zoneinfo/$timezone" /etc/localtime
+        end
+
         and arch-chroot "$mountDir" hwclock --systohc
 
         and begin