rules_file

Bazel rules for basic file operations, such as creating directories and formatting.

Directory

Create a directory from files:

load("@rules_file//file:rules.bzl", "directory")

directory(
    name = "example",
    srcs = glob(["**/*.txt"]),
)

Create a directory from a tarball:

load("@rules_file//file:rules.bzl", "untar")

untar(
    name = "example",
    src = "example.tar",
)

Package-less Files

Access files without regard to package structure. This can be helpful for formatting or Bazel integration tests.

Workspace Example

Create a new repository containing all workspace files.

WORKSPACE.bazel

files(
    name = "files"
    build = "BUILD.file.bazel",
    root_file = "//:WORKSPACE.bazel",
)

BAZEL.bazel

load("@rules_file//file:rules.bzl", "bazelrc_deleted_packages")

bazelrc_deleted_packages(
    name = "bazelrc",
    output = "deleted_packages.bazelrc",
    packages = ["@files//:packages"],
)

files.bazel

# note: files is the symlink to the workspace
filegroup(
    name = "example",
    srcs = glob(["files/**/*.txt"]),
    visibility = ["//visibility:public"],
)

Generate deleted_packages.bazelrc:

bazel run :bazelrc

(To check if this is up-to-date, run bazel run :bazelrc.diff.)

.bazelrc

import %workspace%/deleted.bazelrc

Now @files//:example is all *.txt files in the workspace.

Bazel Integration Test Example

Use files in the test directory as data for a Bazel integration test.

BAZEL.bazel

load("@rules_file//file:rules.bzl", "bazelrc_deleted_packages", "find_packages")

filegroup(
    name = "test",
    srcs = glob(["test/**/*.bazel" "test/**/*.txt"]),
)

find_packages(
    name = "test_packages",
    roots = ["test"],
)

bazelrc_deleted_packages(
    name = "bazelrc",
    output = "deleted_packages.bazelrc",
    packages = [":test_packages"],
)

Generate deleted_packages.bazelrc by running:

bazel run :bazelrc

.bazelrc

import %workspace%/deleted_packages.bazelrc

Generate

In some cases, it is necessary to version control build products in the workspace (bootstrapping, working with other tools).

These rules build the outputs, and copy them to the workspace or check for differences.

BUILD.bazel

load("@rules_file//file:rules.bzl", "bazelrc_deleted_packages")
load("@rules_file//file:rules.bzl", "generate", "generate_test")

genrule(
    name = "example",
    cmd = "echo GENERATED! > $@",
    outs = ["out/example.txt"],
)

generate(
    name = "example_gen",
    srcs = "example.txt",
    data = ["out/example.txt"],
    data_strip_prefix = "out",
)

generate_test(
    name = "example_diff",
    generate = ":example_gen",
)

bazelrc_deleted_packages(
    name = "gen_bazelrc",
    output = "deleted.bazelrc",
    packages = ["@files//:packages"],
)

To overwrite the workspace file:

bazel run :example_gen

To check for differences (e.g. in CI):

bazel test :example_diff

Format

Formatting is a particular case of the checked-in build products pattern.

The code formatting is a regular Bazel action. The formatted result can be using to overwrite workspace files, or to check for differences.

This repository has rules for buildifier, black, and gofmt. It is also used for prettier.

Buildifier Example

WORKSPACE.bazel

load("@rules_file//buildifier:workspace.bzl", "buildifier_repositories", "buildifier_toolchains")

buildifier_repositories()

buildifier_toolchains()

files(
    name = "files"
    build = "BUILD.file.bazel",
    root_file = "//:WORKSPACE.bazel",
)

The @rules_file//buildifier:toolchain_type toolchain will download a pre-build executable of buildifier, if it exists. Otherwise, it will rely on the @com_github_bazelbuild_buildtools repo to build from source.

BUILD.bazel

load("@rules_file//generate:rules.bzl", "format", "generate_test")

format(
    name = "buildifier_format",
    srcs = ["@files//:buildifier_files"],
    formatter = "@rules_file//buildifier",
    strip_prefix = "files",
)

generate_test(
    name = "buildifier_diff",
    generate = ":format",
)

files.bazel

filegroup(
    name = "buildifier_files",
    srcs = glob(
        [
            "files/**/*.bazel",
            "files/**/*.bzl",
            "files/**/BUILD",
            "files/**/WORKSPACE",
        ],
    ),
    visibility = ["//visibility:public"],
)

Generate deleted_packages.bazelrc:

bazel run :gen_bazelrc

.bazelrc

import %workspace%/deleted_packages.bazelrc

To format:

bazel run :buildifier_format

To check format:

bazel run :buildifier_diff