domani/flake.nix

{
  inputs = {
    naersk.url = "github:nix-community/naersk/master";
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-22.11";
    utils.url = "github:numtide/flake-utils";

    rust-overlay.url = "github:oxalica/rust-overlay";
  };

  outputs = { self, nixpkgs, utils, naersk, rust-overlay }:
    let
      buildTargetsBySystem = {
        "x86_64-linux" = "x86_64-unknown-linux-musl";
        "i686-linux" = "i686-unknown-linux-musl";
        "aarch64-linux" = "aarch64-unknown-linux-musl";
      };

      supportedSystems = builtins.attrNames buildTargetsBySystem;

      eachCrossSystem = callback: (builtins.foldl'
        (overall: buildSystem: overall // {
          ${buildSystem} = (builtins.foldl'
            (inner: hostSystem: inner // {
              "cross-${hostSystem}" = callback buildSystem hostSystem;
            })
            { default = callback buildSystem buildSystem; }
            supportedSystems
          );
        })
        {}
        supportedSystems
      );

      mkPkgs = buildSystem: hostSystem: import nixpkgs ({
        system = buildSystem;
        overlays = [
          (import rust-overlay)
          (final: prev: {
            rust-toolchain = prev.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
          })
        ];
      } // (if buildSystem == hostSystem then {} else {
        # The nixpkgs cache doesn't have any packages where cross-compiling has
        # been enabled, even if the target platform is actually the same as the
        # build platform (and therefore it's not really cross-compiling). So we
        # only set up the cross-compiling config if the target platform is
        # different.
        crossSystem.config = hostSystem;
      }));

      mkRustEnv = crossPkgs: hostSystem: {
        OPENSSL_STATIC = "1";
        OPENSSL_LIB_DIR = "${crossPkgs.pkgsStatic.openssl.out}/lib";
        OPENSSL_INCLUDE_DIR = "${crossPkgs.pkgsStatic.openssl.dev}/include";
        CARGO_BUILD_TARGET = buildTargetsBySystem.${hostSystem};
        CARGO_BUILD_RUSTFLAGS = [
          "-C" "target-feature=+crt-static"
          "-C" "linker=${crossPkgs.stdenv.cc}/bin/${crossPkgs.stdenv.cc.targetPrefix}cc"
          "-C" "link-arg=-static"
        ];
      };

    in
    {
      packages = eachCrossSystem (buildSystem: hostSystem: let
        pkgs = mkPkgs buildSystem buildSystem;
        crossPkgs = mkPkgs buildSystem hostSystem;
        naersk-lib = pkgs.callPackage naersk {
          cargo = pkgs.rust-toolchain;
          rustc = pkgs.rust-toolchain;
        };
        rustEnv = mkRustEnv crossPkgs hostSystem;
      in
        naersk-lib.buildPackage ({
          src = ./.;
          doCheck = false;
          nativeBuildInputs = [ crossPkgs.pkgsStatic.stdenv.cc ];
        } // rustEnv)
      );

      devShells = eachCrossSystem (buildSystem: hostSystem: let
        pkgs = mkPkgs buildSystem buildSystem;
        crossPkgs = mkPkgs buildSystem hostSystem;
        rustEnv = mkRustEnv crossPkgs hostSystem;
      in
        pkgs.mkShell ({
          nativeBuildInputs = [
            crossPkgs.stdenv.cc
            crossPkgs.openssl
            pkgs.nmap # ncat
            pkgs.rust-toolchain
          ];
          shellHook = ''
            export CARGO_HOME=$(pwd)/.cargo

            if [ -f "config.yml" ]; then
              export DOMANI_CONFIG_PATH=config-dev.yml
            fi
          '';
        } // rustEnv));
    };
}