nixos-config/template/rust/flake.nix

{
  inputs = {
    crane.url = "github:ipetkov/crane";
    flake-utils.url = "github:numtide/flake-utils";
    fenix.url = "github:nix-community/fenix";
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
    advisory-db = {
      flake = false;
      url = "github:rustsec/advisory-db";
    };
  };

  outputs = { self, crane, fenix, flake-utils, nixpkgs, advisory-db }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};
        fenixPkgs = fenix.packages.${system};
        craneLib = crane.lib.${system};
        src = craneLib.path ./.;

        # Common arguments can be set here to avoid repeating them later
        commonArgs = with pkgs; {
          inherit src;
          strictDeps = true;
          buildInputs = [
            # Add additional build inputs here
          ] ++ lib.optionals stdenv.isDarwin [
            # Additional darwin specific inputs can be set here
            libiconv
          ];

          # Additional environment variables can be set directly
          # MY_CUSTOM_VAR = "some value";
        };

        craneLibLLvmTools = craneLib.overrideToolchain fenixPkgs.complete;

        # Build *just* the cargo dependencies, so we can reuse
        # all of that work (e.g. via cachix) when running in CI
        cargoArtifacts = craneLib.buildDepsOnly commonArgs;

        # Build the actual crate itself, reusing the dependency
        # artifacts from above.
        crate = craneLib.buildPackage (commonArgs // {
          inherit cargoArtifacts;
        });
      in
      {
        checks = {
          # Build the crate as part of `nix flake check` for convenience
          inherit crate;

          # Run clippy (and deny all warnings) on the crate source,
          # again, resuing the dependency artifacts from above.
          #
          # Note that this is done as a separate derivation so that
          # we can block the CI if there are issues here, but not
          # prevent downstream consumers from building our crate by itself.
          clippy = craneLib.cargoClippy (commonArgs // {
            inherit cargoArtifacts;
            cargoClippyExtraArgs = "--all-targets -- --deny warnings";
          });

          doc = craneLib.cargoDoc (commonArgs // {
            inherit cargoArtifacts;
          });

          # Check formatting
          fmt = craneLib.cargoFmt {
            inherit src;
          };

          # Audit dependencies
          audit = craneLib.cargoAudit {
            inherit src advisory-db;
          };

          # Audit licenses
          deny = craneLib.cargoDeny {
            inherit src;
          };

          # Run tests with cargo-nextest
          # Consider setting `doCheck = false` on `my-crate` if you do not want
          # the tests to run twice
          nextest = craneLib.cargoNextest (commonArgs // {
            inherit cargoArtifacts;
            partitions = 1;
            partitionType = "count";
          });
        };

        packages = {
          default = crate;
          llvm-coverage = craneLibLLvmTools.cargoLlvmCov (commonArgs // {
            inherit cargoArtifacts;
          });
        };

        apps.default = flake-utils.lib.mkApp {
          drv = crate;
        };

        devShells.default = craneLib.devShell {
          # Inherit inputs from checks.
          # Enable after Cargo.toml and Cargo.lock are present
          # Consider customizing deny.toml
          # checks = self.checks.${system};

          # Extra inputs can be added here; cargo and rustc are provided by default
          packages = [
            fenixPkgs.rust-analyzer
          ];
          RUST_SRC_PATH = "${fenixPkgs.complete.rust-src}/lib/rustlib/src/rust/library";
        };
      });
}