如何使用Bazel同时编译多个平台目标？

Question

编译单一平台：

# BUILD
load("@io_bazel_rules_go//go:def.bzl", "go_binary")
go_binary(
      name = 'example',
      srcs = glob(["src/*.go"]),
)

虽然编译可以正常进行，但如果我想编译多个平台，只能用以下方法：

bazel build --platforms=@io_bazel_rules_go//go/toolchain:linux_amd64 //:example
bazel build --platforms=@io_bazel_rules_go//go/toolchain:linux_386 //:example
bazel build --platforms=@io_bazel_rules_go//go/toolchain:windows_amd64 //:example
bazel build --platforms=@io_bazel_rules_go//go/toolchain:darwin_amd64 //:example

我希望一次编译多个平台的目标，所以我尝试了这个：

# BUILD
load("//:matrix.bzl", "build_all_platform")


build_all_platform(
    name = 'example',
    pkg = glob(["src/*.go"]),
)

# matrix.bzl
load("@io_bazel_rules_go//go:def.bzl", "go_binary")

SUPPORTED_MATRIX = [
  ("windows", "amd64"),
  ("darwin", "amd64"),
  ("linux", "amd64"),
  ("linux", "386"),
]

def _build(ctx):
    for goos, goarch in SUPPORTED_MATRIX:
        target_name = 'proxy-download-' + goos + '-' + goarch
        if goos == 'windows':
            target_name += '.exe'

        go_binary(
            name = target_name,
            srcs = ctx.attr.pkg,
            pure = "auto",
            goos = goos,
            goarch = goarch,
        )

build_all_platform = rule(
    _build,
     attrs = {
        'pkg': attr.string_list(),
      },
      executable = True,
)

但是遇到了一个错误，我认为这可能是由于rules_go造成的原因。

Traceback (most recent call last):
    File "/source/proxy-download/BUILD", line 4
        build_all_platform(name = 'proxy-download')
    File "/source/proxy-download/matrix.bzl", line 16, in _build
        go_binary(name = target_name, <4 more arguments>)
    File "/private/var/tmp/_bazel_/071099b99a462d431baf96a3ef76cd28/external/io_bazel_rules_go/go/private/rules/wrappers.bzl", line 50, in go_binary
        go_transition_wrapper(go_binary, <3 more arguments>)
    File "/private/var/tmp/_bazel_/071099b99a462d431baf96a3ef76cd28/external/io_bazel_rules_go/go/private/rules/transition.bzl", line 60, in go_transition_wrapper
        transition_kind(name = name, <1 more arguments>)
'rule' can only be called during the loading phase

尝试在此问题提到的多个平台上同时通过测试。

bazel build --platforms=@io_bazel_rules_go//go/toolchain:linux_386,@io_bazel_rules_go//go/toolchain:linux_amd64 //:example

> WARNING: --platforms only supports a single target platform: using the first option @io_bazel_rules_go//go/toolchain:linux_386

参考此代码，使用构建命令行实现此操作。

options = [
    "go",
    "build",
    "-o", output_file.path,
    "-compiler", "gc",
    "-gcflags", '"all=-trimpath=${GOPATH}/src"',
    "-asmflags", '"all=-trimpath=${GOPATH}/src"',
    "-ldflags", "'%s'" % ld_flags,
    "-tags", "'%s'" % ctx.attr.gotags,
    pkg,
  ]

- Spirytus Rektyfikowany

Answer 1

你可能想要查看Bazel的用户定义的转换，它可以使用不同的构建配置来构建依赖关系。请注意，这是一个实验性功能，并非所有构建参数都可配置。

- ArtemB