nixpkgs/doc/languages-frameworks/go.section.md
2022-12-08 02:29:18 +10:00

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# Go {#sec-language-go}
## Go modules {#ssec-language-go}
The function `buildGoModule` builds Go programs managed with Go modules. It builds a [Go Modules](https://github.com/golang/go/wiki/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` {#ex-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](#sec-source-hashes)).
- `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 dependant `vendorHash` checksums.
```nix
pet = buildGoModule rec {
pname = "pet";
version = "0.3.4";
src = fetchFromGitHub {
owner = "knqyf263";
repo = "pet";
rev = "v${version}";
hash = "sha256-Gjw1dRrgM8D3G7v6WIM2+50r4HmTXvx0Xxme2fH9TlQ=";
};
vendorHash = "sha256-ciBIR+a1oaYH+H1PcC8cD8ncfJczk1IiJ8iYNM+R6aA=";
meta = with lib; {
description = "Simple command-line snippet manager, written in Go";
homepage = "https://github.com/knqyf263/pet";
license = licenses.mit;
maintainers = with maintainers; [ kalbasit ];
};
}
```
## `buildGoPackage` (legacy) {#ssec-go-legacy}
The function `buildGoPackage` builds legacy Go programs, not supporting Go modules.
### Example for `buildGoPackage` {#example-for-buildgopackage}
In the following is an example expression using buildGoPackage, the following arguments are of special significance to the function:
- `goPackagePath` specifies the package's canonical Go import path.
- `goDeps` is where the Go dependencies of a Go program are listed as a list of package source identified by Go import path. It could be imported as a separate `deps.nix` file for readability. The dependency data structure is described below.
```nix
deis = buildGoPackage rec {
pname = "deis";
version = "1.13.0";
goPackagePath = "github.com/deis/deis";
src = fetchFromGitHub {
owner = "deis";
repo = "deis";
rev = "v${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`:
```nix
# 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](https://github.com/kamilchm/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:
```bash
for p in $NIX_PROFILES; do
GOPATH="$p/share/go:$GOPATH"
done
```
## Attributes used by the builders {#ssec-go-common-attributes}
Both `buildGoModule` and `buildGoPackage` can be tweaked to behave slightly differently, if the following attributes are used:
### `ldflags` {#var-go-ldflags}
Arguments to pass to the Go linker tool via the `-ldflags` argument of `go build`. The most common use case for this argument is to make the resulting executable aware of its own version. For example:
```nix
ldflags = [
"-s" "-w"
"-X main.Version=${version}"
"-X main.Commit=${version}"
];
```
### `tags` {#var-go-tags}
Arguments to pass to the Go via the `-tags` argument of `go build`. For example:
```nix
tags = [
"production"
"sqlite"
];
```
```nix
tags = [ "production" ] ++ lib.optionals withSqlite [ "sqlite" ];
```
### `deleteVendor` {#var-go-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` {#var-go-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` {#var-go-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.