core/default.nix

@@ -1,8 +1,10 @@
+{ lib, ... }:
+let
+    settings = import ./../settings.nix;
+in
 {
-    imports = [
+    imports = lib.optionals settings.printing.enable [ ./printing.nix ]
-        ./java.nix
+        ++ lib.optionals settings.xdg.enable [ ./xdg.nix ]
-        ./dotnet.nix
+        ++ lib.optionals settings.java [ ./java.nix ]
-        ./printing.nix
+        ++ lib.optionals settings.dotnet [ ./dotnet.nix ];
-        ./xdg.nix
-    ];
 }

core/printing.nix

@@ -1,5 +1,14 @@
-{ pkgs, config, ... }: {
+{ pkgs, lib, config, ... }:
+let
+    settings = import ./../settings.nix;
+in
+{
+    config = lib.mkMerge [
+        {
             services.printing.enable = true;
+        }
+        # Avahi daemon
+        (lib.mkIf settings.printing.avahi {
             services.avahi.enable = true;
             # for a WiFi printer
             services.avahi.openFirewall = true;
@@ -10,4 +19,6 @@
                 (mkBefore [ "mdns4_minimal [NOTFOUND=return]" ]) # before resolve
                 (mkAfter [ "mdns4" ]) # after dns
             ]);
+        })
+    ];
 }

core/xdg.nix

@@ -1,15 +1,12 @@
-{ pkgs, config, ... }: {
+{ pkgs, ... }:
-
+let
+    settings = import ./../settings.nix;
+in
+{
     xdg.portal = {
         enable = true;
-        extraPortals = [
+        extraPortals = settings.xdg.extraPortals;
-            pkgs.xdg-desktop-portal-gtk
-            pkgs.xdg-desktop-portal-kde
-        ];
     };
 
-    environment.systemPackages = with pkgs; [
+    environment.systemPackages = settings.xdg.extraPortals;
-        pkgs.xdg-desktop-portal-gtk
-        pkgs.xdg-desktop-portal-kde
-    ];
 }

settings.nix

@@ -1,4 +1,4 @@
-{
+with import <nixpkgs> {}; {
     hardware = {
         # support for GPUs
         amdgpu = true;
@@ -16,6 +16,19 @@
 
     dvd = true;     # enable DVD decryption + ripping via Handbrake
     bluray = true;  # enable Bluray decryption (requires additional setup)
+    printing = {
+        enable = true;
+        avahi = true;
+    };
+    xdg = {
+        enable = true;
+        extraPortals = with pkgs; [
+            xdg-desktop-portal-gtk
+            xdg-desktop-portal-kde
+        ];
+    };
+    java = true;
+    dotnet = true;
 
     networking = {
         wireguard = true;   # enable wireguard protocol