Move several options to a ‘defaults’ file

base/default.nix

@@ -1,6 +1,7 @@
 { ... }:
 {
     imports = [
+        ./defaults.nix
         ./xkb
         ./neovim.nix
         ./packages.nix

base/defaults.nix

@@ -0,0 +1,14 @@
+{ lib, ... }:
+with lib;
+{
+    i18n.defaultLocale = mkDefault "en_GB.UTF-8";
+    console.keyMap = mkDefault "de";
+    services.openssh.enable = mkDefault true;
+    services.openssh.passwordAuthentication = mkDefault false;
+
+    nix.gc = mkDefault {
+        automatic = true;
+        dates = "weekly";
+        options = "--delete-older-than 30d";
+    };
+}

base/locale.nix

@@ -2,9 +2,7 @@
 {
     time.timeZone = "Europe/Berlin";
 
-    i18n.defaultLocale = "en_GB.UTF-8";
     console = {
         font = "Lat2-Terminus16";
-        keyMap = "de";
     };
 }

hosts/Rupert.nix

@@ -88,12 +88,6 @@ in
     system.autoUpgrade.sendEmail = true;
     # systemd.services.nixos-upgrade.onFailure = lib.mkIf config.system.autoUpgrade.enable [ "status-email@%n.service" ];
 
-    nix.gc = {
-        automatic = true;
-        dates = "weekly";
-        options = "--delete-older-than 30d";
-    };
-
     services.btrfsScrub = {
         enable = true;
         paths = {