core/pkgs/build-support/go/module.nix

{
  go,
  cacert,
  git,
  lib,
  stdenv,
}:

{
  name ? "${args'.pname}-${args'.version}",
  src,
  nativeBuildInputs ? [ ],
  passthru ? { },
  patches ? [ ],

  # A function to override the goModules derivation
  overrideModAttrs ? (_oldAttrs: { }),

  # path to go.mod and go.sum directory
  modRoot ? "./",

  # vendorHash is the SRI hash of the vendored dependencies
  #
  # if vendorHash is null, then we won't fetch any dependencies and
  # rely on the vendor folder within the source.
  vendorHash ? throw (
    if args' ? vendorSha256 then
      "buildGoModule: Expect vendorHash instead of vendorSha256"
    else
      "buildGoModule: vendorHash is missing"
  ),
  # Whether to delete the vendor folder supplied with the source.
  deleteVendor ? false,
  # Whether to fetch (go mod download) and proxy the vendor directory.
  # This is useful if your code depends on c code and go mod tidy does not
  # include the needed sources to build or if any dependency has case-insensitive
  # conflicts which will produce platform dependant `vendorHash` checksums.
  proxyVendor ? false,

  # We want parallel builds by default
  enableParallelBuilding ? true,

  # Do not enable this without good reason
  # IE: programs coupled with the compiler
  allowGoReference ? false,

  CGO_ENABLED ? go.CGO_ENABLED,

  meta ? { },

  # Not needed with buildGoModule
  goPackagePath ? "",

  ldflags ? [ ],

  GOFLAGS ? [ ],

  # needed for buildFlags{,Array} warning
  buildFlags ? "",
  buildFlagsArray ? "",

  ...
}@args':

assert goPackagePath != "" -> throw "`goPackagePath` is not needed with `buildGoModule`";

let
  args = removeAttrs args' [
    "overrideModAttrs"
    "vendorSha256"
    "vendorHash"
  ];

  GO111MODULE = "on";
  GOTOOLCHAIN = "local";

  goModules =
    if (vendorHash == null) then
      ""
    else
      (stdenv.mkDerivation {
        name = "${name}-go-modules";

        nativeBuildInputs = (args.nativeBuildInputs or [ ]) ++ [
          go
          git
          cacert
        ];

        inherit (args) src;
        inherit (go) GOOS GOARCH;
        inherit GO111MODULE GOTOOLCHAIN;

        # The following inheritence behavior is not trivial to expect, and some may
        # argue it's not ideal. Changing it may break vendor hashes in Nixpkgs and
        # out in the wild. In anycase, it's documented in:
        # doc/languages-frameworks/go.section.md
        prePatch = args.prePatch or "";
        patches = args.patches or [ ];
        patchFlags = args.patchFlags or [ ];
        postPatch = args.postPatch or "";
        preBuild = args.preBuild or "";
        postBuild = args.modPostBuild or "";
        sourceRoot = args.sourceRoot or "";
        env = args.env or { };

        impureEnvVars = lib.fetchers.proxyImpureEnvVars ++ [
          "GIT_PROXY_COMMAND"
          "SOCKS_SERVER"
          "GOPROXY"
        ];

        configurePhase =
          args.modConfigurePhase or ''
            runHook preConfigure
            export GOCACHE=$TMPDIR/go-cache
            export GOPATH="$TMPDIR/go"
            cd "${modRoot}"
            runHook postConfigure
          '';

        buildPhase =
          args.modBuildPhase or (
            ''
              runHook preBuild
            ''
            + lib.optionalString deleteVendor ''
              if [ ! -d vendor ]; then
                echo "vendor folder does not exist, 'deleteVendor' is not needed"
                exit 10
              else
                rm -rf vendor
              fi
            ''
            + ''
              if [ -d vendor ]; then
                echo "vendor folder exists, please set 'vendorHash = null;' in your expression"
                exit 10
              fi

              ${
                if proxyVendor then
                  ''
                    mkdir -p "''${GOPATH}/pkg/mod/cache/download"
                    go mod download
                  ''
                else
                  ''
                    if (( "''${NIX_DEBUG:-0}" >= 1 )); then
                      goModVendorFlags+=(-v)
                    fi
                    go mod vendor "''${goModVendorFlags[@]}"
                  ''
              }

              mkdir -p vendor

              runHook postBuild
            ''
          );

        installPhase =
          args.modInstallPhase or ''
            runHook preInstall

            ${
              if proxyVendor then
                ''
                  rm -rf "''${GOPATH}/pkg/mod/cache/download/sumdb"
                  cp -r --reflink=auto "''${GOPATH}/pkg/mod/cache/download" $out
                ''
              else
                ''
                  cp -r --reflink=auto vendor $out
                ''
            }

            if ! [ "$(ls -A $out)" ]; then
              echo "vendor folder is empty, please set 'vendorHash = null;' in your expression"
              exit 10
            fi

            runHook postInstall
          '';

        dontFixup = true;

        outputHashMode = "recursive";
        outputHash = vendorHash;
        # Handle empty vendorHash; avoid
        # error: empty hash requires explicit hash algorithm
        outputHashAlgo = if vendorHash == "" then "sha256" else null;
      }).overrideAttrs
        overrideModAttrs;

  package = stdenv.mkDerivation (
    args
    // {
      nativeBuildInputs = [ go ] ++ nativeBuildInputs;

      inherit (go) GOOS GOARCH;

      GOFLAGS =
        GOFLAGS
        ++ lib.optional (!proxyVendor) "-mod=vendor"
        ++ lib.optional (!allowGoReference) "-trimpath";
      inherit
        CGO_ENABLED
        enableParallelBuilding
        GO111MODULE
        GOTOOLCHAIN
        ;

      # If not set to an explicit value, set the buildid empty for reproducibility.
      ldflags = ldflags ++ lib.optional (!lib.any (lib.hasPrefix "-buildid=") ldflags) "-buildid=";

      configurePhase =
        args.configurePhase or (
          ''
            runHook preConfigure

            export GOCACHE=$TMPDIR/go-cache
            export GOPATH="$TMPDIR/go"
            export GOPROXY=off
            export GOSUMDB=off
            cd "$modRoot"
          ''
          + lib.optionalString (vendorHash != null) ''
            ${
              if proxyVendor then
                ''
                  export GOPROXY=file://${goModules}
                ''
              else
                ''
                  rm -rf vendor
                  cp -r --reflink=auto ${goModules} vendor
                ''
            }
          ''
          + ''

            # currently pie is only enabled by default in pkgsMusl
            # this will respect the `hardening{Disable,Enable}` flags if set
            if [[ $NIX_HARDENING_ENABLE =~ "pie" ]]; then
              export GOFLAGS="-buildmode=pie $GOFLAGS"
            fi

            runHook postConfigure
          ''
        );

      buildPhase =
        args.buildPhase or (
          ''
            runHook preBuild

            exclude='\(/_\|examples\|Godeps\|testdata'
            if [[ -n "$excludedPackages" ]]; then
              IFS=' ' read -r -a excludedArr <<<$excludedPackages
              printf -v excludedAlternates '%s\\|' "''${excludedArr[@]}"
              excludedAlternates=''${excludedAlternates%\\|} # drop final \| added by printf
              exclude+='\|'"$excludedAlternates"
            fi
            exclude+='\)'

            buildGoDir() {
              local cmd="$1" dir="$2"

              . $TMPDIR/buildFlagsArray

              declare -a flags
              flags+=($buildFlags "''${buildFlagsArray[@]}")
              flags+=(''${tags:+-tags=''${tags// /,}})
              flags+=(''${ldflags:+-ldflags="$ldflags"})
              flags+=("-p" "$NIX_BUILD_CORES")

              if [ "$cmd" = "test" ]; then
                flags+=(-vet=off)
                flags+=($checkFlags)
              fi

              local OUT
              if ! OUT="$(go $cmd "''${flags[@]}" $dir 2>&1)"; then
                if ! echo "$OUT" | grep -qE '(no( buildable| non-test)?|build constraints exclude all) Go (source )?files'; then
                  echo "$OUT" >&2
                  return 1
                fi
              fi
              if [ -n "$OUT" ]; then
                echo "$OUT" >&2
              fi
              return 0
            }

            getGoDirs() {
              local type;
              type="$1"
              if [ -n "$subPackages" ]; then
                echo "$subPackages" | sed "s,\(^\| \),\1./,g"
              else
                find . -type f -name \*$type.go -exec dirname {} \; | grep -v "/vendor/" | sort --unique | grep -v "$exclude"
              fi
            }

            if (( "''${NIX_DEBUG:-0}" >= 1 )); then
              buildFlagsArray+=(-x)
            fi

            if [ ''${#buildFlagsArray[@]} -ne 0 ]; then
              declare -p buildFlagsArray > $TMPDIR/buildFlagsArray
            else
              touch $TMPDIR/buildFlagsArray
            fi
            if [ -z "$enableParallelBuilding" ]; then
                export NIX_BUILD_CORES=1
            fi
            for pkg in $(getGoDirs ""); do
              echo "Building subPackage $pkg"
              buildGoDir install "$pkg"
            done
          ''
          + lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''
            # normalize cross-compiled builds w.r.t. native builds
            (
              dir=$GOPATH/bin/${go.GOOS}_${go.GOARCH}
              if [[ -n "$(shopt -s nullglob; echo $dir/*)" ]]; then
                mv $dir/* $dir/..
              fi
              if [[ -d $dir ]]; then
                rmdir $dir
              fi
            )
          ''
          + ''
            runHook postBuild
          ''
        );

      doCheck = args.doCheck or true;
      checkPhase =
        args.checkPhase or ''
          runHook preCheck
          # We do not set trimpath for tests, in case they reference test assets
          export GOFLAGS=''${GOFLAGS//-trimpath/}

          for pkg in $(getGoDirs test); do
            buildGoDir test "$pkg"
          done

          runHook postCheck
        '';

      installPhase =
        args.installPhase or ''
          runHook preInstall

          mkdir -p $out
          dir="$GOPATH/bin"
          [ -e "$dir" ] && cp -r $dir $out

          runHook postInstall
        '';

      strictDeps = true;

      disallowedReferences = lib.optional (!allowGoReference) go;

      passthru = passthru // {
        inherit go goModules vendorHash;
      };

      meta = {
        # Add default meta information
        platforms = go.meta.platforms or lib.platforms.all;
      } // meta;
    }
  );
in
lib.warnIf (buildFlags != "" || buildFlagsArray != "")
  "Use the `ldflags` and/or `tags` attributes instead of `buildFlags`/`buildFlagsArray`"
  lib.warnIf
  (builtins.elem "-buildid=" ldflags)
  "`-buildid=` is set by default as ldflag by buildGoModule"
  lib.warnIf
  (builtins.elem "-trimpath" GOFLAGS)
  "`-trimpath` is added by default to GOFLAGS by buildGoModule when allowGoReference isn't set to true"
  lib.warnIf
  (lib.any (lib.hasPrefix "-mod=") GOFLAGS)
  "use `proxyVendor` to control Go module/vendor behavior instead of setting `-mod=` in GOFLAGS"
  package