modules: create an option to enable the overlay

This way, nothing changes in the configuration if you add the module to it and
do nothing else

Author: Andy3153

modules/decky-loader.nix

@@ -2,6 +2,7 @@
 
 let
   inherit (lib)
+    mkForce
     mkIf
     mkOption
     types
@@ -86,6 +87,8 @@ in
       # run plugins. Running as non-root is unsupported and currently breaks:
       #
       # <https://github.com/SteamDeckHomebrew/decky-loader/issues/446#issuecomment-1637177368>
+      jovian.overlay.enable = mkForce true;
+
       systemd.services.decky-loader = {
         description = "Steam Deck Plugin Loader";
 

modules/devices/steamdeck/fan-control.nix

@@ -4,6 +4,7 @@
 
 let
   inherit (lib)
+    mkForce
     mkIf
     mkOption
     types
@@ -27,6 +28,8 @@ in
   };
 
   config = mkIf (cfg.enableOsFanControl) {
+    jovian.overlay.enable = mkForce true;
+
     systemd.services.jupiter-fan-control = {
       wantedBy = [ "multi-user.target" ];
       path = [ pkgs.dmidecode ];

modules/devices/steamdeck/firmware.nix

@@ -4,6 +4,7 @@
 
 let
   inherit (lib)
+    mkForce
     mkIf
     mkMerge
     mkOption
@@ -35,18 +36,24 @@ in
 
   config = mkMerge [
     (mkIf (cfg.enable) {
+      jovian.overlay.enable = mkForce true;
+
       hardware.firmware = [
         (lib.hiPrio pkgs.linux-firmware-jupiter)
         (lib.hiPrio pkgs.steamdeck-dsp)
       ];
     })
     (mkIf (cfg.autoUpdate) {
+      jovian.overlay.enable = mkForce true;
+
       systemd.packages = [pkgs.steamdeck-firmware];
 
       systemd.services.jupiter-biosupdate.wantedBy = ["multi-user.target"];
       systemd.services.jupiter-controller-update.wantedBy = ["multi-user.target"];
     })
     (mkIf (cfg.enableFwupdBiosUpdates) {
+      jovian.overlay.enable = mkForce true;
+
       services.fwupd.enable = true;
 
       environment.etc."fwupd/remotes.d/steamdeck-bios.conf".text = ''

modules/devices/steamdeck/kernel.nix

@@ -3,6 +3,7 @@
 let
   inherit (lib)
     mkDefault
+    mkForce
     mkIf
     mkMerge
     mkOption
@@ -26,6 +27,8 @@ in
   };
   config = mkIf (cfg.enableKernelPatches) (mkMerge [
     {
+      jovian.overlay.enable = mkForce true;
+
       boot.kernelPackages = mkDefault pkgs.linuxPackages_jovian;
       # see https://github.com/Jovian-Experiments/steamos-customizations-jupiter/blob/jupiter-20241107.1/misc/modules-load.d/hid-preload.conf
       boot.kernelModules = ["hid_nintendo" "hid_playstation"];

modules/devices/steamdeck/sdgyrodsu.nix

@@ -2,6 +2,7 @@
 
 let
   inherit (lib)
+    mkForce
     mkIf
     mkOption
     types
@@ -24,6 +25,8 @@ in
     };
   };
   config = mkIf cfg.enableGyroDsuService {
+    jovian.overlay.enable = mkForce true;
+
     systemd.user.services.sdgyrodsu = {
       description = "Cemuhook DSU server for the Steam Deck Gyroscope";
       wantedBy = [ "graphical-session.target" ];

modules/devices/steamdeck/sound.nix

@@ -8,7 +8,7 @@ let
 
     # override acp5x configs with Jovian stuff
     cp -rf ${pkgs.steamdeck-dsp}/share/alsa $out/share
-    
+
     # remove more specific upstream symlink so Valve acp5x config is picked
     rm $out/share/alsa/ucm2/conf.d/acp5x/Valve-Jupiter-1.conf
   '';
@@ -32,6 +32,8 @@ in
 
     extraEnv.ALSA_CONFIG_UCM2 = "${alsa-ucm-conf'}/share/alsa/ucm2";
   in lib.mkIf cfg.enableSoundSupport {
+    jovian.overlay.enable = lib.mkForce true;
+
     services.pulseaudio.enable = false;
 
     services.pipewire = {

modules/jovian/overlay.nix

@@ -1,16 +1,39 @@
-{ lib, ... }:
-
+{ config, lib, ... }:
+let
+  inherit (lib)
+    mkIf
+    mkOption
+    types
+  ;
+  cfg = config.jovian.overlay;
+in
 {
-  nixpkgs.overlays = [
-    (import ../../overlay.nix)
-  ];
+  options = {
+    jovian.overlay = {
+      enable = mkOption {
+        type = types.bool;
+        default = config.jovian.steam.enable;
+        defaultText = "config.jovian.steam.enable";
+        description = ''
+          Whether to enable the provided overlay over Nixpkgs.
+        '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    nixpkgs.overlays = [
+      (import ../../overlay.nix)
+    ];
 
-  assertions = [
-    {
-      # Can't use 23.11 here because git versions are tracked as 23.11pre,
-      # which is considered to be < 23.11.
-      assertion = lib.versionAtLeast lib.version "23.10";
-      message = "Jovian NixOS is only validated with the nixos-unstable branch of Nixpkgs. Please upgrade your Nixpkgs version.";
-    }
-  ];
+    assertions = [
+      {
+        # Can't use 23.11 here because git versions are tracked as 23.11pre,
+        # which is considered to be < 23.11.
+        assertion = lib.versionAtLeast lib.version "23.10";
+        message = "Jovian NixOS is only validated with the nixos-unstable branch of Nixpkgs. Please upgrade your Nixpkgs version.";
+      }
+    ];
+  };
 }
+

modules/steam/autostart.nix

@@ -3,6 +3,7 @@
 let
   inherit (lib)
     mkDefault
+    mkForce
     mkIf
     mkMerge
     mkOption
@@ -32,7 +33,7 @@ in
         };
 
         desktopSession = mkOption {
-          type = with types ; nullOr str // {         
+          type = with types ; nullOr str // {
             check = userProvidedDesktopSession:
               lib.assertMsg (userProvidedDesktopSession != null -> (str.check userProvidedDesktopSession && lib.elem userProvidedDesktopSession config.services.displayManager.sessionData.sessionNames)) ''
                   Desktop session '${userProvidedDesktopSession}' not found.
@@ -76,6 +77,8 @@ in
         to keep this behavior.
       '';
 
+      jovian.overlay.enable = mkForce true;
+
       services.displayManager.enable = true;
 
       systemd.user.services.gamescope-session = {

modules/steam/environment.nix

@@ -1,4 +1,4 @@
-{ config, lib, pkgs, ... }:
+{ config, lib, ... }:
 
 let
   inherit (lib)

modules/steam/steam.nix

@@ -3,6 +3,7 @@
 let
   inherit (lib)
     mkDefault
+    mkForce
     mkIf
     mkMerge
   ;
@@ -17,6 +18,8 @@ in
           "The Steam Deck UI integrates with NetworkManager (networking.networkmanager.enable) which is not enabled. NetworkManager is required to complete the first-time setup process.";
     }
     {
+      jovian.overlay.enable = mkForce true;
+
       security.wrappers.gamescope = {
         owner = "root";
         group = "root";
@@ -32,6 +35,8 @@ in
       };
     }
     {
+      jovian.overlay.enable = mkForce true;
+
       # Enable the usual desktop Steam stuff
       programs.steam.enable = mkDefault true;