project-templates/rust.nix

{
  flake-parts-lib,
  inputs,
  ...
}: {
  flake = {
    templates = {
      rust = {
        path = ./rust;
        description = "A rust flake with crane and templates for command args and configs";
      };
    };

    flakeModules.rust = {
      imports = [
        inputs.treefmt-nix.flakeModule
      ];

      options.perSystem = flake-parts-lib.mkPerSystemOption ({
        lib,
        config,
        pkgs,
        ...
      }: let
        cfg = config.krantz.rust;

        craneLib = inputs.crane.mkLib pkgs;
        src = craneLib.cleanCargoSource cfg.src;
        manifest = (lib.importTOML "${src}/Cargo.toml").package;

        buildInputs = cfg.runtimeDeps;

        # build dependencies
        nativeBuildInputs = cfg.buildDeps;

        # Build *just* the cargo dependencies, so we can reuse
        # all of that work (e.g. via cachix) when running in CI
        cargoArtifacts = craneLib.buildDepsOnly {
          inherit src buildInputs nativeBuildInputs;
        };
      in {
        options.krantz.rust = {
          enable = lib.mkEnableOption "building a cargo project with crane";

          src = lib.mkOption {
            description = "The path to the root of the crate.";
            type = lib.types.path;
            example = lib.literalExpression "./.";
          };
          srcFiltered = lib.mkOption {
            description = "A path to the filtered directory of the root of the crate.";
            type = lib.types.path;
            default = craneLib.cleanCargoSource cfg.src;
            defaultText = lib.literalExpression "config.krantz.rust.craneLib cfg.src";
            example = lib.literalExpression "./.";
          };

          runtimeDeps = lib.mkOption {
            description = "Packages needed for the app to run.";
            type = lib.types.listOf lib.types.package;
            default = [];
            example = with pkgs; [
              openssl
            ];
          };
          buildDeps = lib.mkOption {
            description = "Packages needed for the app to build.";
            type = lib.types.listOf lib.types.package;
            default = [];
            example = with pkgs; [
              pkg-config
              rustPlatform.bindgenHook
            ];
          };
          devDeps = lib.mkOption {
            description = "Packages to include only in the devShell.";
            type = lib.types.listOf lib.types.package;
            default = with pkgs; [
              rust-analyzer
            ];
          };

          devShell = {
            enable = lib.mkEnableOption "a rust development environment" // {default = true;};

            name = lib.mkOption {
              description = "The name of the attribute in devShells to configure";
              type = lib.types.str;
              default = "default";
              example = "rust";
            };

            extraAttr = lib.mkOption {
              description = "Extra attributes to merge into the devshell. See https://crane.dev/API.html#cranelibdevshell";
              type = lib.types.attrs;
              default = {};
              example = {
                shellHook = ''
                  export DEBUG=1
                '';
              };
            };
          };

          package = {
            enable = lib.mkEnableOption "the compiled cargo project" // {default = true;};

            name = lib.mkOption {
              description = "The name of the attribute in packages to configure";
              type = lib.types.str;
              default = "default";
              example = "lib";
            };

            extraAttr = lib.mkOption {
              description = "Extra attributes to merge into the package. See https://crane.dev/API.html#cranelibbuildpackage";
              type = lib.types.attrs;
              default = {};
              example = {
                doCheck = false;
              };
            };
          };

          craneLib = lib.mkOption {
            description = "The crane lib instance this module is using. Useful for overriding options";
            default = craneLib;
            defaultText = lib.literalExpression "crane.mkLib pkgs";
            readOnly = true;
          };
        };

        config = lib.mkIf cfg.enable rec {
          # Dev Shell that lets you enter an environment with all the necessary utilites
          # Available through 'nix develop'
          # Also can be activated automatically if direnv is installed on the system with 'direnv allow'
          devShells.${cfg.devShell.name} = lib.mkIf cfg.devShell.enable (craneLib.devShell {
              inherit checks;

              # extra tooling dependencies
              packages = cfg.devDeps;

              inputsFrom = [packages.default];
            }
            // cfg.devShell.extraAttr);

          # Formatter for nix files, available through 'nix fmt'
          treefmt = {
            programs.alejandra.enable = lib.mkDefault true;
            programs.rustfmt = {
              enable = true;
              edition = manifest.edition;
            };
          };

          # Your custom packages
          # Accessible through 'nix build', 'nix shell', 'nix run', etc
          packages.${cfg.package.name} = lib.mkIf cfg.package.enable (craneLib.buildPackage {
              inherit src buildInputs nativeBuildInputs cargoArtifacts;
            }
            // cfg.package.extraAttr);

          checks = {
            clippy = craneLib.cargoClippy {
              inherit src buildInputs nativeBuildInputs cargoArtifacts;
              cargoClippyExtraArgs = "-- --deny warnings";
            };
          };
        };
      });
    };
  };
}