nixpkgs/nixos/modules/services/desktops/pipewire/pipewire.nix

# pipewire service.
{ config, lib, pkgs, ... }:

with lib;

let
  cfg = config.services.pipewire;
  enable32BitAlsaPlugins = cfg.alsa.support32Bit
                           && pkgs.stdenv.isx86_64
                           && pkgs.pkgsi686Linux.pipewire != null;

  # The package doesn't output to $out/lib/pipewire directly so that the
  # overlays can use the outputs to replace the originals in FHS environments.
  #
  # This doesn't work in general because of missing development information.
  jack-libs = pkgs.runCommand "jack-libs" {} ''
    mkdir -p "$out/lib"
    ln -s "${cfg.package.jack}/lib" "$out/lib/pipewire"
  '';
in {
  meta.maintainers = teams.freedesktop.members ++ [ lib.maintainers.k900 ];

  ###### interface
  options = {
    services.pipewire = {
      enable = mkEnableOption (lib.mdDoc "pipewire service");

      package = mkOption {
        type = types.package;
        default = pkgs.pipewire;
        defaultText = literalExpression "pkgs.pipewire";
        description = lib.mdDoc ''
          The pipewire derivation to use.
        '';
      };

      socketActivation = mkOption {
        default = true;
        type = types.bool;
        description = lib.mdDoc ''
          Automatically run pipewire when connections are made to the pipewire socket.
        '';
      };

      audio = {
        enable = lib.mkOption {
          type = lib.types.bool;
          # this is for backwards compatibility
          default = cfg.alsa.enable || cfg.jack.enable || cfg.pulse.enable;
          defaultText = lib.literalExpression "config.services.pipewire.alsa.enable || config.services.pipewire.jack.enable || config.services.pipewire.pulse.enable";
          description = lib.mdDoc "Whether to use PipeWire as the primary sound server";
        };
      };

      alsa = {
        enable = mkEnableOption (lib.mdDoc "ALSA support");
        support32Bit = mkEnableOption (lib.mdDoc "32-bit ALSA support on 64-bit systems");
      };

      jack = {
        enable = mkEnableOption (lib.mdDoc "JACK audio emulation");
      };

      pulse = {
        enable = mkEnableOption (lib.mdDoc "PulseAudio server emulation");
      };

      systemWide = lib.mkOption {
        type = lib.types.bool;
        default = false;
        description = lib.mdDoc ''
          If true, a system-wide PipeWire service and socket is enabled
          allowing all users in the "pipewire" group to use it simultaneously.
          If false, then user units are used instead, restricting access to
          only one user.

          Enabling system-wide PipeWire is however not recommended and disabled
          by default according to
          https://github.com/PipeWire/pipewire/blob/master/NEWS
        '';
      };
    };
  };

  imports = [
    (lib.mkRemovedOptionModule ["services" "pipewire" "config"] ''
      Overriding default Pipewire configuration through NixOS options never worked correctly and is no longer supported.
      Please create drop-in files in /etc/pipewire/pipewire.conf.d/ to make the desired setting changes instead.
    '')

    (lib.mkRemovedOptionModule ["services" "pipewire" "media-session"] ''
      pipewire-media-session is no longer supported upstream and has been removed.
      Please switch to `services.pipewire.wireplumber` instead.
    '')
  ];

  ###### implementation
  config = mkIf cfg.enable {
    assertions = [
      {
        assertion = cfg.audio.enable -> !config.hardware.pulseaudio.enable;
        message = "Using PipeWire as the sound server conflicts with PulseAudio. This option requires `hardware.pulseaudio.enable` to be set to false";
      }
      {
        assertion = cfg.jack.enable -> !config.services.jack.jackd.enable;
        message = "PipeWire based JACK emulation doesn't use the JACK service. This option requires `services.jack.jackd.enable` to be set to false";
      }
      {
        # JACK intentionally not checked, as PW-on-JACK setups are a thing that some people may want
        assertion = (cfg.alsa.enable || cfg.pulse.enable) -> cfg.audio.enable;
        message = "Using PipeWire's ALSA/PulseAudio compatibility layers requires running PipeWire as the sound server. Set `services.pipewire.audio.enable` to true.";
      }
    ];

    environment.systemPackages = [ cfg.package ]
                                 ++ lib.optional cfg.jack.enable jack-libs;

    systemd.packages = [ cfg.package ];

    # PipeWire depends on DBUS but doesn't list it. Without this booting
    # into a terminal results in the service crashing with an error.
    systemd.services.pipewire.bindsTo = [ "dbus.service" ];
    systemd.user.services.pipewire.bindsTo = [ "dbus.service" ];

    # Enable either system or user units.  Note that for pipewire-pulse there
    # are only user units, which work in both cases.
    systemd.sockets.pipewire.enable = cfg.systemWide;
    systemd.services.pipewire.enable = cfg.systemWide;
    systemd.user.sockets.pipewire.enable = !cfg.systemWide;
    systemd.user.services.pipewire.enable = !cfg.systemWide;

    # Mask pw-pulse if it's not wanted
    systemd.user.services.pipewire-pulse.enable = cfg.pulse.enable;
    systemd.user.sockets.pipewire-pulse.enable = cfg.pulse.enable;

    systemd.sockets.pipewire.wantedBy = lib.mkIf cfg.socketActivation [ "sockets.target" ];
    systemd.user.sockets.pipewire.wantedBy = lib.mkIf cfg.socketActivation [ "sockets.target" ];
    systemd.user.sockets.pipewire-pulse.wantedBy = lib.mkIf cfg.socketActivation [ "sockets.target" ];

    services.udev.packages = [ cfg.package ];

    # If any paths are updated here they must also be updated in the package test.
    environment.etc."alsa/conf.d/49-pipewire-modules.conf" = mkIf cfg.alsa.enable {
      text = ''
        pcm_type.pipewire {
          libs.native = ${cfg.package}/lib/alsa-lib/libasound_module_pcm_pipewire.so ;
          ${optionalString enable32BitAlsaPlugins
            "libs.32Bit = ${pkgs.pkgsi686Linux.pipewire}/lib/alsa-lib/libasound_module_pcm_pipewire.so ;"}
        }
        ctl_type.pipewire {
          libs.native = ${cfg.package}/lib/alsa-lib/libasound_module_ctl_pipewire.so ;
          ${optionalString enable32BitAlsaPlugins
            "libs.32Bit = ${pkgs.pkgsi686Linux.pipewire}/lib/alsa-lib/libasound_module_ctl_pipewire.so ;"}
        }
      '';
    };
    environment.etc."alsa/conf.d/50-pipewire.conf" = mkIf cfg.alsa.enable {
      source = "${cfg.package}/share/alsa/alsa.conf.d/50-pipewire.conf";
    };
    environment.etc."alsa/conf.d/99-pipewire-default.conf" = mkIf cfg.alsa.enable {
      source = "${cfg.package}/share/alsa/alsa.conf.d/99-pipewire-default.conf";
    };

    environment.sessionVariables.LD_LIBRARY_PATH =
      lib.mkIf cfg.jack.enable [ "${cfg.package.jack}/lib" ];

    users = lib.mkIf cfg.systemWide {
      users.pipewire = {
        uid = config.ids.uids.pipewire;
        group = "pipewire";
        extraGroups = [
          "audio"
          "video"
        ] ++ lib.optional config.security.rtkit.enable "rtkit";
        description = "Pipewire system service user";
        isSystemUser = true;
        home = "/var/lib/pipewire";
        createHome = true;
      };
      groups.pipewire.gid = config.ids.gids.pipewire;
    };
  };
}