depot/nixos/modules/programs/nix-required-mounts.nix

{
  config,
  lib,
  pkgs,
  ...
}:

let
  cfg = config.programs.nix-required-mounts;
  package = pkgs.nix-required-mounts;

  Mount =
    with lib;
    types.submodule {
      options.host = mkOption {
        type = types.str;
        description = "Host path to mount";
      };
      options.guest = mkOption {
        type = types.str;
        description = "Location in the sandbox to mount the host path at";
      };
    };
  Pattern =
    with lib.types;
    types.submodule (
      { config, name, ... }:
      {
        options.onFeatures = lib.mkOption {
          type = listOf types.str;
          description = "Which requiredSystemFeatures should trigger relaxation of the sandbox";
          default = [ name ];
        };
        options.paths = lib.mkOption {
          type = listOf (oneOf [
            path
            Mount
          ]);
          description = "A list of glob patterns, indicating which paths to expose to the sandbox";
        };
        options.unsafeFollowSymlinks = lib.mkEnableOption ''
          Instructs the hook to mount the symlink targets as well, when any of
          the `paths` contain symlinks. This may not work correctly with glob
          patterns.
        '';
      }
    );

  driverPaths = [
    pkgs.addDriverRunpath.driverLink

    # mesa:
    config.hardware.opengl.package

    # nvidia_x11, etc:
  ] ++ config.hardware.opengl.extraPackages; # nvidia_x11

  defaults = {
    nvidia-gpu.onFeatures = package.allowedPatterns.nvidia-gpu.onFeatures;
    nvidia-gpu.paths = package.allowedPatterns.nvidia-gpu.paths ++ driverPaths;
    nvidia-gpu.unsafeFollowSymlinks = false;
  };
in
{
  meta.maintainers = with lib.maintainers; [ SomeoneSerge ];
  options.programs.nix-required-mounts = {
    enable = lib.mkEnableOption "Expose extra paths to the sandbox depending on derivations' requiredSystemFeatures";
    presets.nvidia-gpu.enable = lib.mkEnableOption ''
      Declare the support for derivations that require an Nvidia GPU to be
      available, e.g. derivations with `requiredSystemFeatures = [ "cuda" ]`.
      This mounts the corresponding userspace drivers and device nodes in the
      sandbox, but only for derivations that request these special features.

      You may extend or override the exposed paths via the
      `programs.nix-required-mounts.allowedPatterns.nvidia-gpu.paths` option.
    '';
    allowedPatterns =
      with lib.types;
      lib.mkOption rec {
        type = attrsOf Pattern;
        description = "The hook config, describing which paths to mount for which system features";
        default = { };
        defaultText = lib.literalExpression ''
          {
            opengl.paths = config.hardware.opengl.extraPackages ++ [
              config.hardware.opengl.package
              pkgs.addDriverRunpath.driverLink
              "/dev/dri"
            ];
          }
        '';
        example.require-ipfs.paths = [ "/ipfs" ];
        example.require-ipfs.onFeatures = [ "ifps" ];
      };
    extraWrapperArgs = lib.mkOption {
      type = with lib.types; listOf str;
      default = [ ];
      description = "List of extra arguments (such as `--add-flags -v`) to pass to the hook's wrapper";
    };
    package = lib.mkOption {
      type = lib.types.package;
      default = package.override { inherit (cfg) allowedPatterns extraWrapperArgs; };
      description = "The final package with the final config applied";
      internal = true;
    };
  };
  config = lib.mkIf cfg.enable (
    lib.mkMerge [
      { nix.settings.pre-build-hook = lib.getExe cfg.package; }
      (lib.mkIf cfg.presets.nvidia-gpu.enable {
        nix.settings.system-features = cfg.allowedPatterns.nvidia-gpu.onFeatures;
        programs.nix-required-mounts.allowedPatterns = {
          inherit (defaults) nvidia-gpu;
        };
      })
    ]
  );
}