bevy/dynamic feature doesn't find vulkan-loader on NixOS

[zyansheep]

Bevy version

Bevy main branch (https://github.com/bevyengine/bevy#e3fb23d4d3828842ab5780d1200b231a7e9549ea)

Operating system & version

NixOS unstable w/ flakes

What you did

Setup my project using the build.rs in #136
I'm using nix flakes so:
nix develop (get build environment)
cargo run --features bevy/dynamic

What you expected to happen

The brick breaker example to run

What actually happened

thread 'main' panicked at 'Unable to find a GPU! Make sure you have installed required drivers!'

Same error when I was fixing the previous error for static building where it didn't link against vulkan & x11

Additional information

It works if I don't do --features bevy/dynamic but the compile time is slow

My flake.nix: (using naersk and fenix to get rust nightly)

{
  	inputs = {
		utils.url = "github:numtide/flake-utils";
		naersk.url = "github:nmattia/naersk";
		fenix.url = "github:nix-community/fenix";
  	};

  	outputs = { self, nixpkgs, utils, naersk, fenix }:
	utils.lib.eachDefaultSystem (system: let
		pkgs = nixpkgs.legacyPackages."${system}";
		# Specify Rust Toolchain
		# Use Stable (Default)
		# naersk-lib = naersk.lib."${system}";
		# Use Nightly (provided by fenix)
		naersk-lib = naersk.lib."${system}".override {
			# Use Fenix to get nightly rust
			inherit (fenix.packages.${system}.minimal) cargo rustc;
		};
	in rec {
		# `nix build`
		packages.ray_game = naersk-lib.buildPackage {
			pname = "ray_game";
			root = ./.;
			buildInputs = with pkgs; [
				# Package location
				pkgconfig
				# Window and Input
				x11
				xorg.libXcursor
				xorg.libXrandr
				xorg.libXi

				# Vulkan
				vulkan-tools
				vulkan-headers
				vulkan-loader
				vulkan-validation-layers
				alsaLib # Sound support
				libudev # device management
				lld # fast linker
			];
		};
		defaultPackage = packages.ray_game;

		# `nix run`
		apps.ray_game = utils.lib.mkApp {
			drv = packages.ray_game;
		};
		defaultApp = apps.ray_game;

		# `nix develop`
		devShell = pkgs.mkShell {
			buildInputs = packages.ray_game.buildInputs;
		};
	});
}

[zyansheep]

with much trial and error, I was able to patchelf my way to get it working with loading the dynamic library, but that's not really a permanent solution. Somehow I need to get cargo to link vulkan correctly...

[bjorn3]

What was the patch that you needed to make?

[zyansheep]

I ran patchelf --add-needed /nix/store/mi44faayr5padcm331wcc4rmqa3bj9pg-vulkan-loader-1.2.162.0/lib/libvulkan.so.1.2.162 target/debug/libbevy_dylib.so so that bevy was able to link with vulkan.

[zyansheep]

Also, I've been using the lld linker for even faster iteration times (<1s) but lld doesn't link most of the libraries correctly to /nix/store so those also have to be patchelf'd manually.

[bjorn3]

NixOS/nixpkgs#24744 seems to be related to your lld issue. I think it has a way to support it, but I am not familiar with nix, so I can't say for sure.

[zyansheep]

NixOS/nixpkgs#24744 seems to be related to your lld issue. I think it has a way to support it, but I am not familiar with nix, so I can't say for sure.

Oh, thanks! That fixed my problem with lld not finding libraries, however vulkan-loader still needs to be linked manually...

[jakeisnt]

Having precisely this issue with linking vulkan-loader as well.

[mdevlamynck]

Using the LD_LIBRARY_PATH export documented in the Nix/NixOS section of amethyst doc solves it for me when using the dev shell. I haven't tested building a package yet though.

Here's the flake I use : https://github.com/mdevlamynck/nix-flake-templates/blob/master/bevy/flake.nix

(btw @zyansheep, you can use the self input (like defaultPackage = self.packages."${system}".ray_game;) to refer to your flake output without needing to use rec { … }.)

[polendri]

Having just gotten Bevy running on a NixOS host via a Nix Flake with the help of @mdevlamynck 's example (thank you!), I just wanted to share the reasons why things weren't working for me, in case it's helpful to anyone else:

• Initially I was using nixpkgs.url = "github:nixos/nixpkgs/nixos-21.05"; as per @mdevlamynck 's flake.nix, but my host is running on the unstable channel, which appears to have been causing linking issues with vulkan at runtime. Switching that to nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable"; appears to have fixed it. It seems counterproductive to need my flake's nixpkgs version to match my host, so if anyone knows what's going on there, I'd be interested to know.
• The first time I fixed the above, I didn't do a cargo clean, so I was still running build artifacts from the previous environment. Doing a full rebuild with every change to flake.nix helped narrow things down properly.

Other things to note:

• I was getting errors when trying to run vkcube in my nix develop . shell, which was leading me to believe that vulkan wasn't working at all within the shell. Turns out this is also do to with my host environment conflicting somehow, since if I open the shell with nix develop . -i -k DISPLAY -k HOME (clearing all my host env vars except for DISPLAY and HOME), vkcube runs fine.
• I don't appear to need the build.rs file described on the wiki section for NixOS.

For reference, here's the flake.nix I've been using.

[freylint]

So I've had a couple hours taken away by this issue.

As this is a higher google result I just want to note some of the pitfalls I've run into.

Make sure

nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";

is set to nixpks and not nixos. (this burnt an hour)

If you want cargo r to work in the dev environment make sure you set shellInputs.

devShells.default = pkgs.mkShell {
  shellInputs = buildInputs;
  shellHook = ''
    export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:${pkgs.lib.makeLibraryPath buildInputs}"
  '';
};

I'll post my flake.nix in its current state in case future revisions break general uses.

My flake.nix

{ description = "A game for the uninspired.";

inputs = {
fenix.url = "github:nix-community/fenix";
nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
flake-utils.url = "github:numtide/flake-utils";
naersk.url = "github:nix-community/naersk";
};
outputs = { self, fenix, naersk, nixpkgs, flake-utils }:
with flake-utils.lib; eachSystem [ system.x86_64-linux ] (system:
let
pkgs = (import nixpkgs) {
inherit system;
};

    # Setup Rust Toolchain for each platform
    toolchain = with fenix.packages.${system};
      combine [
        minimal.rustc
        minimal.cargo
        targets.x86_64-unknown-linux-gnu.latest.rust-std
      ];

    naersk' =
      naersk.lib.${system}.override {
        cargo = toolchain;
        rustc = toolchain;
      };

    nativeBuildInputs = with pkgs; [
      pkgconfig
      clang
    ];
    buildInputs = with pkgs; [
      udev
      alsaLib
      vulkan-loader
      xlibsWrapper
      xorg.libXcursor
      xorg.libXrandr
      xorg.libXi
      libxkbcommon
      wayland
    ] ++ assetInputs;
    assetInputs = with pkgs; [
      python3
      inkscape
      blender
      imagemagick
    ];
  in
  rec {
    # Setup checks for each platform
    #checks = packages."${system}";
    packages.default = packages."${system}";

    devShells.default = pkgs.mkShell {
      #shellInputs = buildInputs;
      shellHook = ''
        export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:${pkgs.lib.makeLibraryPath buildInputs}"
      '';
    };

    packages."x86_64-linux" = naersk'.buildPackage {
      src = ./.;
      enableParallelBuilding = true;

      nativeBuildInputs = nativeBuildInputs;
      buildInputs = buildInputs;

      #postInstall = ''
      #  python3 assets/scripts/build-assets.py
      #  cp -r assets/build $out/bin/assets/build/
      #'';

      shellHook = ''
        export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:${pkgs.lib.makeLibraryPath buildInputs}"
      '';
    };
  }
);

}


Even after all of this I still have to do nix devel; nix run to get a working window.

[lucasMontenegro]

For anyone trying to integrate a Cargo project with nix, take a look at nci.