NixOS: add setting services.printing.enableAutoDiscovery

nix/nixos-modules/extends/default.nix

@@ -2,5 +2,6 @@
   imports = [
     # files
     ./podman.nix
+    ./printing.nix
   ];
 }

nix/nixos-modules/extends/printing.nix

@@ -0,0 +1,25 @@
+{ config, lib, ... }:
+let
+  cfg = config.services.printing;
+in
+{
+
+  options.services.printing = {
+    enableAutoDiscovery = lib.mkEnableOption ''
+      CUPS automatic discovery of printers.
+
+      This will enable & configure Avahi accordingly,
+      including opening ports in the firewall'';
+  };
+
+  config = lib.mkIf cfg.enable {
+    # TODO make also possible with systemd-resolved
+    services.avahi = lib.mkIf cfg.enableAutoDiscovery {
+      enable = true;
+      nssmdns4 = true;
+      nssmdns6 = true;
+      openFirewall = true;
+    };
+  };
+
+}