depot/third_party/nixpkgs/doc/languages-frameworks/go.section.md

Go

Go modules

The function buildGoModule builds Go programs managed with Go modules. It builds a Go Modules through a two phase build:

• An intermediate fetcher derivation. This derivation will be used to fetch all of the dependencies of the Go module.
• A final derivation will use the output of the intermediate derivation to build the binaries and produce the final output.

Example for buildGoModule

In the following is an example expression using buildGoModule, the following arguments are of special significance to the function:

• vendorHash: is the hash of the output of the intermediate fetcher derivation.

  vendorHash can also be set to null. In that case, rather than fetching the dependencies and vendoring them, the dependencies vendored in the source repo will be used.

  To avoid updating this field when dependencies change, run go mod vendor in your source repo and set vendorHash = null;

  To obtain the actual hash, set vendorHash = lib.fakeSha256; and run the build (more details here).

• proxyVendor: Fetches (go mod download) and proxies 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-dependent vendorHash checksums.

• modPostBuild: Shell commands to run after the build of the goModules executes go mod vendor, and before calculating fixed output derivation's vendorHash (or vendorSha256). Note that if you change this attribute, you need to update vendorHash (or vendorSha256) attribute.

pet = buildGoModule rec {
  pname = "pet";
  version = "0.3.4";

  src = fetchFromGitHub {
    owner = "knqyf263";
    repo = "pet";
    rev = "v${version}";
    hash = "sha256-Gjw1dRrgM8D3G7v6WIM2+50r4HmTXvx0Xxme2fH9TlQ=";
  };

  vendorHash = "sha256-ciBIR+a1oaYH+H1PcC8cD8ncfJczk1IiJ8iYNM+R6aA=";

  meta = with lib; {
    description = "Simple command-line snippet manager, written in Go";
    homepage = "https://github.com/knqyf263/pet";
    license = licenses.mit;
    maintainers = with maintainers; [ kalbasit ];
  };
}

buildGoPackage (legacy)

The function buildGoPackage builds legacy Go programs, not supporting Go modules.

Example for buildGoPackage

In the following is an example expression using buildGoPackage, the following arguments are of special significance to the function:

• goPackagePath specifies the package's canonical Go import path.
• goDeps is where the Go dependencies of a Go program are listed as a list of package source identified by Go import path. It could be imported as a separate deps.nix file for readability. The dependency data structure is described below.

deis = buildGoPackage rec {
  pname = "deis";
  version = "1.13.0";

  goPackagePath = "github.com/deis/deis";

  src = fetchFromGitHub {
    owner = "deis";
    repo = "deis";
    rev = "v${version}";
    hash = "sha256-XCPD4LNWtAd8uz7zyCLRfT8rzxycIUmTACjU03GnaeM=";
  };

  goDeps = ./deps.nix;
}

The goDeps attribute can be imported from a separate nix file that defines which Go libraries are needed and should be included in GOPATH for buildPhase:

# deps.nix
[ # goDeps is a list of Go dependencies.
  {
    # goPackagePath specifies Go package import path.
    goPackagePath = "gopkg.in/yaml.v2";
    fetch = {
      # `fetch type` that needs to be used to get package source.
      # If `git` is used there should be `url`, `rev` and `hash` defined next to it.
      type = "git";
      url = "https://gopkg.in/yaml.v2";
      rev = "a83829b6f1293c91addabc89d0571c246397bbf4";
      hash = "sha256-EMrdy0M0tNuOcITaTAmT5/dPSKPXwHDKCXFpkGbVjdQ=";
    };
  }
  {
    goPackagePath = "github.com/docopt/docopt-go";
    fetch = {
      type = "git";
      url = "https://github.com/docopt/docopt-go";
      rev = "784ddc588536785e7299f7272f39101f7faccc3f";
      hash = "sha256-Uo89zjE+v3R7zzOq/gbQOHj3SMYt2W1nDHS7RCUin3M=";
    };
  }
]

To extract dependency information from a Go package in automated way use go2nix. It can produce complete derivation and goDeps file for Go programs.

You may use Go packages installed into the active Nix profiles by adding the following to your ~/.bashrc:

for p in $NIX_PROFILES; do
    GOPATH="$p/share/go:$GOPATH"
done

Attributes used by the builders

Many attributes controlling the build phase are respected by both buildGoModule and buildGoPackage. Note that buildGoModule reads the following attributes also when building the vendor/ goModules fixed output derivation as well:

• sourceRoot
• prePatch
• patches
• patchFlags
• postPatch
• preBuild

In addition to the above attributes, and the many more variables respected also by stdenv.mkDerivation, both buildGoModule and buildGoPackage respect Go-specific attributes that tweak them to behave slightly differently:

ldflags

Arguments to pass to the Go linker tool via the -ldflags argument of go build. The most common use case for this argument is to make the resulting executable aware of its own version. For example:

  ldflags = [
    "-s" "-w"
    "-X main.Version=${version}"
    "-X main.Commit=${version}"
  ];

tags

Arguments to pass to the Go via the -tags argument of go build. For example:

  tags = [
    "production"
    "sqlite"
  ];

  tags = [ "production" ] ++ lib.optionals withSqlite [ "sqlite" ];

deleteVendor

Removes the pre-existing vendor directory. This should only be used if the dependencies included in the vendor folder are broken or incomplete.

subPackages

Specified as a string or list of strings. Limits the builder from building child packages that have not been listed. If subPackages is not specified, all child packages will be built.

excludedPackages

Specified as a string or list of strings. Causes the builder to skip building child packages that match any of the provided values. If excludedPackages is not specified, all child packages will be built.