是否可以从.bzl文件中加载通用规则？

Question

我们经常需要每个技术堆栈的通用规则组合。这目前在工作空间中浪费了大量空间-它们应该在多个repos中保持同步。它是构建器后面的50+行，包含太多的urls、版本和散列。

现在假设我有一个“技术堆栈”代码库，并执行如下操作

load("@techstack_repo//mylang.bzl", "load_rules")
load_rules()

load_rules会在哪里加载和初始化固定的版本，例如rules_go，bazel-gazelle，rules_docker，rules_proto，并以正确的顺序初始化所有它们，以便它们在工作区中可见？

我没有在我的测试中让它工作，因为load显然不能在bzl文件中的函数中运行-它本身不是一个函数。

有没有办法做到这一点？

下面是我为Java测试的一个示例：

load("@io_bazel_rules_docker//repositories:repositories.bzl", container_repositories = "repositories")
load("@io_bazel_rules_docker//repositories:deps.bzl", container_deps = "deps")
load("@io_bazel_rules_docker//container:container.bzl", "container_pull")
load("@rules_proto//proto:repositories.bzl", "rules_proto_dependencies", "rules_proto_toolchains")
load(
    "@io_grpc_grpc_java//:repositories.bzl",
    "IO_GRPC_GRPC_JAVA_ARTIFACTS",
    "IO_GRPC_GRPC_JAVA_OVERRIDE_TARGETS",
    "grpc_java_repositories",
)
load("@rules_jvm_external//:defs.bzl", "maven_install")

def prepare_stack(maven_deps = []):
    container_repositories()
    container_deps()
    container_pull(
        name = "java_base",
        # https://console.cloud.google.com/gcr/images/distroless/GLOBAL/java-debian10
        # tag = "11", # OpenJDK 11 as of 2020-03-04
        digest = "sha256:eda9e5ae2facccc9c7016f0c2d718d2ee352743bda81234783b64aaa402679b6",
        registry = "gcr.io",
        repository = "distroless/java-debian10",
    )
    rules_proto_dependencies()
    rules_proto_toolchains()
    maven_install(
        artifacts = maven_deps + IO_GRPC_GRPC_JAVA_ARTIFACTS,
        # for improved debugging in IDE
        fetch_sources = True,
        generate_compat_repositories = True,
        override_targets = IO_GRPC_GRPC_JAVA_OVERRIDE_TARGETS,
        repositories = [
            "https://repo.maven.apache.org/maven2/",
            "https://repo1.maven.org/maven2",
        ],
        strict_visibility = True,
    )
    grpc_java_repositories()

..。规则存储库的所有http_archive调用都是用WORKSPACE编写的，我想把它们移到这里，但这根本不起作用。按照原样，我得到了这个错误：

ERROR: Failed to load Starlark extension '@rules_python//python:pip.bzl'.
Cycle in the workspace file detected. This indicates that a repository is used prior to being defined.
The following chain of repository dependencies lead to the missing definition.
 - @rules_python
This could either mean you have to add the '@rules_python' repository with a statement like `http_archive` in your WORKSPACE file (note that transitive dependencies are not added automatically), or move an existing definition earlier in your WORKSPACE file.

此外，添加rules_python也无济于事。

Answer 1

我找到了一个解决方案：

将其拆分为两个文件。其中一个包含这样的导入：

load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")

def declare():
    maybe(
        git_repository,
        name = "rules_cc",
        commit = "34ca16f4aa4bf2a5d3e4747229202d6cb630ebab",
        remote = "https://github.com/bazelbuild/rules_cc.git",
        shallow_since = "1584036492 -0700",
    )
    # ... for me requires at least rules_cc, rules_python, bazel_skylib
    # for later proto, docker, go, java support

另一种是使用声明的外部源：

# go
load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_dependencies")
load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies")

# protobuf
load("@rules_proto//proto:repositories.bzl", "rules_proto_dependencies", "rules_proto_toolchains")

# container
load("@io_bazel_rules_docker//container:container.bzl", "container_pull")
load("@io_bazel_rules_docker//repositories:repositories.bzl", container_repositories = "repositories")
load("@io_bazel_rules_docker//repositories:deps.bzl", container_deps = "deps")
load("@io_bazel_rules_docker//go:image.bzl", go_image_repositories = "repositories")

def init_rules():
    go_rules_dependencies()
    go_register_toolchains()
    gazelle_dependencies()
    rules_proto_dependencies()
    rules_proto_toolchains()
    container_repositories()
    container_deps()
    go_image_repositories()
    container_pull(
        name = "go_static",
        digest = "sha256:9b60270ec0991bc4f14bda475e8cae75594d8197d0ae58576ace84694aa75d7a",
        registry = "gcr.io",
        repository = "distroless/static",
    )

这有点麻烦，但是用http_archive或git_repository获取这个代码库，加载第一个文件并调用declare，为init_rules加载第二个文件并调用它。

这可能有点复杂，但它仍然有助于统一堆栈和简化您的WORKSPACE。