punktfunk/nix

punktfunk on NixOS / Nix

First-class Nix support via the repo's flake.nix: reproducible builds of the streaming host and the native Linux client, a NixOS module that wires up everything the RPM/deb do (systemd user service, udev rules, kernel modules, sysctl tuning, firewall, input group), and a dev shell with the pinned toolchain and every system library.

Platform: x86_64-linux only (the host encodes with desktop NVENC; matches the RPM's ExclusiveArch: x86_64). NixOS 24.11 or newer for the hardware.graphics option.

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What the flake provides

Output	Contents
packages.x86_64-linux.punktfunk-host	punktfunk-host + punktfunk-tray (built with nvenc + vulkan-encode, like CI)
packages.x86_64-linux.punktfunk-client	punktfunk-client (GTK4 shell) + punktfunk-session (Vulkan streamer, without the Skia OSD — see caveats)
packages.x86_64-linux.default	= punktfunk-host
nixosModules.default	services.punktfunk.host / services.punktfunk.client
devShells.x86_64-linux.default	pinned Rust (from rust-toolchain.toml) + all build deps
apps / checks / formatter	nix run, nix flake check, nix fmt

One binary per GPU vendor: NVENC/CUDA entry points are dlopen'd at runtime, so the host runs on NVIDIA (zero-copy dmabuf → CUDA → NVENC), AMD/Intel (raw Vulkan-Video HEVC / VAAPI), or software.

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Quick start (no NixOS required)

# Build
nix build git+https://git.unom.io/unom/punktfunk#punktfunk-host
nix build git+https://git.unom.io/unom/punktfunk#punktfunk-client

# Run
nix run git+https://git.unom.io/unom/punktfunk#punktfunk-host -- serve --gamestream
nix run git+https://git.unom.io/unom/punktfunk#punktfunk-client

GPU drivers are resolved at runtime from /run/opengl-driver/lib. On non-NixOS distros use nixGL so that path is populated (nixGL nix run …); on NixOS the module (below) sets hardware.graphics.enable = true for you.

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NixOS module

Add the flake and enable the host and/or client:

{
  inputs.punktfunk.url = "git+https://git.unom.io/unom/punktfunk";
  # (optional) share your nixpkgs: inputs.punktfunk.inputs.nixpkgs.follows = "nixpkgs";

  outputs = { self, nixpkgs, punktfunk, ... }: {
    nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";
      modules = [
        punktfunk.nixosModules.default
        ({ ... }: {
          services.punktfunk.host = {
            enable = true;
            users = [ "alice" ];        # → added to the `input` group for virtual gamepads
            openFirewall = true;        # native + GameStream ports
            settings = {
              PUNKTFUNK_VIDEO_SOURCE = "virtual";
              RUST_LOG = "info";
              # PUNKTFUNK_444 = true;   # booleans render as 1/0
            };
          };

          # …and/or the client on the same or another box:
          services.punktfunk.client = {
            enable = true;
            openFirewall = true;        # UDP 5353 for mDNS discovery
          };
        })
      ];
    };
  };
}

Then, in your graphical session:

systemctl --user enable --now punktfunk-host

Options

services.punktfunk.host:

Option	Default	Meaning
enable	false	Install the host + wire udev/sysctl/kernel-modules/firewall and the user service.
gamestream	true	serve --gamestream (Moonlight-compatible). false = native-only, more secure.
autoStart	false	Add the user service to default.target (appliance mode — pair with lingering).
users	[ ]	Users added to the input group (virtual gamepads).
settings	{ }	host.env key/values (see ${package}/share/punktfunk-host/host.env.example).
environmentFile	null	Extra EnvironmentFile for secrets (e.g. PUNKTFUNK_MGMT_TOKEN); loaded optionally.
openFirewall	false	Open the inbound ports (see below).
package	flake's	Override the package.

services.punktfunk.client: enable, openFirewall (UDP 5353), package.

What the host module configures for you

Everything the RPM's %install + %post do, declaratively:

• systemd --user service punktfunk-host → serve [--gamestream], EnvironmentFile from settings (+ optional secret file), Restart=on-failure.
• udev rules (60-punktfunk.rules): /dev/uinput + /dev/uhid group access and the vhci sysfs perms for the virtual Steam Deck.
• kernel modules: uinput, uhid, vhci-hcd (usbip transport so Steam Input adopts the virtual Deck).
• sysctl: net.core.{r,w}mem_max = 32 MB (high-bitrate UDP headroom; mkDefault).
• input group membership for users.
• hardware.graphics.enable = true (mkDefault) so /run/opengl-driver/lib has the driver libs the binaries dlopen.
• firewall (when openFirewall): native UDP 9777/5353 + TCP 47990; with gamestream also TCP 47984/47989/48010 + UDP 47998/47999/48000. The media data plane is an ephemeral, hole-punched UDP port — nothing fixed to open.
• tray autostart entry (--autostart; self-gates to users who actually run a host).

GPU drivers (out of scope of the module — set these yourself)

• NVIDIA: hardware.nvidia + hardware.graphics.enable = true. NVENC/CUDA come from the driver at runtime (nothing pinned in the closure).
• AMD/Intel: hardware.graphics.enable = true with extraPackages = [ vaapiVdpau … ] / intel-media-driver for VAAPI encode; the host's raw Vulkan-Video HEVC path needs only Mesa.

Headless / appliance

Set autoStart = true, enable lingering, and pick a backend in settings:

services.punktfunk.host = {
  enable = true;
  autoStart = true;
  users = [ "streamer" ];
  settings = { PUNKTFUNK_COMPOSITOR = "gamescope"; };  # or kwin/mutter/wlroots
};
users.users.streamer.linger = true;
# For the gamescope/KWin backends extend the service PATH, e.g.:
# systemd.user.services.punktfunk-host.path = [ pkgs.gamescope ];

The ${package}/share/punktfunk-host/headless/ helpers (KDE/Sway session scripts, example host.env files, the OpenAPI doc) are installed for reference.

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Development

nix develop        # pinned toolchain (rust-toolchain.toml) + all system libs
cargo build --release -p punktfunk-host -p punktfunk-client-linux -p punktfunk-client-session -p punktfunk-tray

The shell exports PF_FFVK_VULKAN_INCLUDE (Vulkan headers for pf-ffvk bindgen) and an LD_LIBRARY_PATH that includes /run/opengl-driver/lib so cargo run finds the GPU driver. nix fmt formats the .nix files.

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Notes & caveats

• Build tool: crane. The lockfile carries windows 0.62.2 from both crates.io and a pinned microsoft/windows-rs git rev (the Windows client), which rustPlatform.importCargoLock can't vendor (colliding name-version); crane vendors per-source and fetches the git rev via builtins.fetchGit (no output hash to maintain). Those crates are cfg(windows)-gated — vendored, never compiled on Linux.
• First build compiles from scratch (no split dep cache — pyrowave-sys builds a CMake tree in its build.rs that a crane "dummy" source would drop) and has no public binary cache, so expect a long initial build. nix develop gives incremental rebuilds.
• Commit flake.lock: it pins the input revisions (nixpkgs / crane / rust-overlay). It is generated on first eval and checked in.
• Session Skia OSD is off under Nix. punktfunk-session's default ui feature draws its on-screen stats/console overlay with skia-safe, whose build downloads a prebuilt Skia from the rust-skia releases — which Nix's network-less build sandbox forbids, and a from-source Skia build pulls the whole gn/ninja/python toolchain plus network-fetched third-party. The feature is explicitly droppable ("same streaming, stats on stdout only"), so the Nix build compiles the session with --no-default-features --features pyrowave. Everything streams; only the session binary's optional on-glass stats overlay is absent, and the GTK shell (punktfunk-client) is skia-free and fully featured. Re-adding it means teaching skia-bindings to consume a prebuilt Skia offline (a fixed-output derivation of the rust-skia tarball) or a vendored from-source Skia build — a tracked follow-up.

Verified

Both packages build, install, and run on real Nix hardware (NixOS-equivalent: CachyOS + Nix, RTX 5070 Ti, driver 610). punktfunk-host --version and punktfunk-session run; the driver RUNPATH (/run/opengl-driver/lib) and the GTK GApps wrapper (GSettings schemas + pixbuf loaders) are present. Fixes discovered during that bring-up: CMAKE_POLICY_VERSION_MINIMUM=3.5 (CMake ≥ 4), system libopus (audiopus_sys), and the session Skia note above.