nixos/wivrn: init module

nixos/doc/manual/release-notes/rl-2405.section.md

@@ -201,6 +201,8 @@ The pre-existing [services.ankisyncd](#opt-services.ankisyncd.enable) has been m
 
 - [watchdogd](https://troglobit.com/projects/watchdogd/), a system and process supervisor using watchdog timers. Available as [services.watchdogd](#opt-services.watchdogd.enable).
 
+- [WiVRn](https://github.com/Meumeu/WiVRn), an OpenXR streaming application. Available as [services.wivrn](#opt-services.wivrn.enable).
+
 - [Workout-tracker](https://github.com/jovandeginste/workout-tracker), a workout tracking web application for personal use.
 
 - [wyoming-satellite](https://github.com/rhasspy/wyoming-satellite), a voice assistant satellite for Home Assistant using the Wyoming protocol. Available as [services.wyoming.satellite](#opt-services.wyoming.satellite.enable).

nixos/modules/module-list.nix

@@ -1367,6 +1367,7 @@
   ./services/video/mediamtx.nix
   ./services/video/unifi-video.nix
   ./services/video/v4l2-relayd.nix
+  ./services/video/wivrn.nix
   ./services/wayland/cage.nix
   ./services/wayland/hypridle.nix
   ./services/web-apps/akkoma.nix

nixos/modules/services/video/wivrn.nix

@@ -0,0 +1,226 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+let
+  inherit (lib)
+    mkIf
+    mkEnableOption
+    mkPackageOption
+    mkOption
+    optionalString
+    optionalAttrs
+    isDerivation
+    recursiveUpdate
+    getExe
+    literalExpression
+    types
+    maintainers
+    ;
+  cfg = config.services.wivrn;
+  configFormat = pkgs.formats.json { };
+
+  # For the application option to work with systemd PATH, we find the store binary path of
+  # the package, concat all of the following strings, and then update the application attribute.
+  # Application can either be a package or a list that has a package as the first element.
+  applicationExists = builtins.hasAttr "application" cfg.config.json;
+  applicationListNotEmpty = (
+    if builtins.isList cfg.config.json.application then
+      (builtins.length cfg.config.json.application) != 0
+    else
+      true
+  );
+  applicationCheck = applicationExists && applicationListNotEmpty;
+
+  applicationBinary = (
+    if builtins.isList cfg.config.json.application then
+      builtins.head cfg.config.json.application
+    else
+      cfg.config.json.application
+  );
+  applicationStrings = builtins.tail cfg.config.json.application;
+
+  applicationPath = mkIf applicationCheck applicationBinary;
+
+  applicationConcat = (
+    if builtins.isList cfg.config.json.application then
+      builtins.concatStringsSep " " ([ (getExe applicationBinary) ] ++ applicationStrings)
+    else
+      (getExe applicationBinary)
+  );
+  applicationUpdate = recursiveUpdate cfg.config.json (
+    optionalAttrs applicationCheck { application = applicationConcat; }
+  );
+  configFile = configFormat.generate "config.json" applicationUpdate;
+in
+{
+  options = {
+    services.wivrn = {
+      enable = mkEnableOption "WiVRn, an OpenXR streaming application";
+
+      package = mkPackageOption pkgs "wivrn" { };
+
+      openFirewall = mkEnableOption "the default ports in the firewall for the WiVRn server";
+
+      defaultRuntime = mkEnableOption ''
+        WiVRn Monado as the default OpenXR runtime on the system.
+        The config can be found at `/etc/xdg/openxr/1/active_runtime.json`.
+
+        Note that applications can bypass this option by setting an active
+        runtime in a writable XDG_CONFIG_DIRS location like `~/.config`
+      '';
+
+      autoStart = mkEnableOption "starting the service by default";
+
+      monadoEnvironment = mkOption {
+        type = types.attrs;
+        description = "Environment variables to be passed to the Monado environment.";
+        default = {
+          XRT_COMPOSITOR_LOG = "debug";
+          XRT_PRINT_OPTIONS = "on";
+          IPC_EXIT_ON_DISCONNECT = "off";
+        };
+      };
+
+      extraPackages = mkOption {
+        type = types.listOf types.package;
+        description = "Packages to add to the wivrn-application service $PATH.";
+        default = [ ];
+        example = literalExpression "[ pkgs.bash pkgs.procps ]";
+      };
+
+      config = {
+        enable = mkEnableOption "configuration for WiVRn";
+        json = mkOption {
+          type = configFormat.type;
+          description = ''
+            Configuration for WiVRn. The attributes are serialized to JSON in config.json.
+
+            Note that the application option must be either a package or a
+            list with package as the first element.
+
+            See https://github.com/Meumeu/WiVRn/blob/master/docs/configuration.md
+          '';
+          default = { };
+          example = literalExpression ''
+            {
+              scale = 0.8;
+              bitrate = 100000000;
+              encoders = [
+                {
+                  encoder = "nvenc";
+                  codec = "h264";
+                  width = 1.0;
+                  height = 1.0;
+                  offset_x = 0.0;
+                  offset_y = 0.0;
+                }
+              ];
+              application = [ pkgs.wlx-overlay-s ];
+              tcp_only = true;
+            }
+          '';
+        };
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = !applicationCheck || isDerivation applicationBinary;
+        message = "The application in WiVRn configuration is not a package. Please ensure that the application is a package or that a package is the first element in the list.";
+      }
+    ];
+
+    systemd.user = {
+      services = {
+        # The WiVRn server runs in a hardened service and starts the applications in a different service
+        wivrn = {
+          description = "WiVRn XR runtime service";
+          environment = {
+            # Default options
+            # https://gitlab.freedesktop.org/monado/monado/-/blob/598080453545c6bf313829e5780ffb7dde9b79dc/src/xrt/targets/service/monado.in.service#L12
+            XRT_COMPOSITOR_LOG = "debug";
+            XRT_PRINT_OPTIONS = "on";
+            IPC_EXIT_ON_DISCONNECT = "off";
+          } // cfg.monadoEnvironment;
+          serviceConfig = {
+            ExecStart = (
+              (getExe cfg.package) + " --systemd" + optionalString cfg.config.enable " -f ${configFile}"
+            );
+            # Hardening options
+            CapabilityBoundingSet = [ "CAP_SYS_NICE" ];
+            AmbientCapabilities = [ "CAP_SYS_NICE" ];
+            LockPersonality = true;
+            NoNewPrivileges = true;
+            PrivateTmp = true;
+            ProtectClock = true;
+            ProtectControlGroups = true;
+            ProtectKernelLogs = true;
+            ProtectKernelModules = true;
+            ProtectKernelTunables = true;
+            ProtectProc = "invisible";
+            ProtectSystem = "strict";
+            RemoveIPC = true;
+            RestrictNamespaces = true;
+            RestrictSUIDSGID = true;
+          };
+          wantedBy = mkIf cfg.autoStart [ "default.target" ];
+          restartTriggers = [
+            cfg.package
+            configFile
+          ];
+        };
+        wivrn-application = mkIf applicationCheck {
+          description = "WiVRn application service";
+          requires = [ "wivrn.service" ];
+          serviceConfig = {
+            ExecStart = (
+              (getExe cfg.package) + " --application" + optionalString cfg.config.enable " -f ${configFile}"
+            );
+            Restart = "on-failure";
+            RestartSec = 0;
+            PrivateTmp = true;
+          };
+          # We need to add the application to PATH so WiVRn can find it
+          path = [ applicationPath ] ++ cfg.extraPackages;
+        };
+      };
+    };
+
+    services = {
+      # WiVRn can be used with some wired headsets so we include xr-hardware
+      udev.packages = with pkgs; [
+        android-udev-rules
+        xr-hardware
+      ];
+      avahi = {
+        enable = true;
+        publish = {
+          enable = true;
+          userServices = true;
+        };
+      };
+    };
+
+    networking.firewall = mkIf cfg.openFirewall {
+      allowedTCPPorts = [ 9757 ];
+      allowedUDPPorts = [ 9757 ];
+    };
+
+    environment = {
+      systemPackages = [
+        cfg.package
+        applicationPath
+      ];
+      pathsToLink = [ "/share/openxr" ];
+      etc."xdg/openxr/1/active_runtime.json" = mkIf cfg.defaultRuntime {
+        source = "${cfg.package}/share/openxr/1/openxr_wivrn.json";
+      };
+    };
+  };
+  meta.maintainers = with maintainers; [ passivelemon ];
+}