Bazel helpers library

Base Starlark libraries and basic Bazel rules which are useful for constructing rulesets and BUILD files.

Relationship to bazel-skylib

This module depends on bazel-skylib. In theory all these utilities could be upstreamed to bazel-skylib, but the declared scope of that project is narrow and it no longer accepts feature requests, see https://github.com/orgs/bazelbuild/discussions/3. It's possible that we may instead remove the dependency on bazel-skylib and entirely replace it, in an ABI-compatible sense. See #927.

Installation

Installation instructions are included on each release: https://github.com/bazel-contrib/bazel-lib/releases

To use a commit rather than a release, you can point at any SHA of the repo. However, this adds more "dev dependencies", as you'll have to build our helper programs (such as copy_to_directory, expand_template) from their Go sources rather than download pre-built binaries.

For example to use commit abc123 in MODULE.bazel:

# Automatically picks up new Go dev dependencies
git_override(
    module_name = "bazel_lib",
    commit = "abc123",
    remote = "[email protected]:bazel-contrib/bazel-lib.git",
)

Or in WORKSPACE:

1. Replace url = "https://github.com/bazel-contrib/bazel-lib/releases/download/v0.1.0/bazel-lib-v0.1.0.tar.gz" with a GitHub-provided source archive like url = "https://github.com/bazel-contrib/bazel-lib/archive/abc123.tar.gz"
2. Replace strip_prefix = "bazel-lib-0.1.0" with strip_prefix = "bazel-lib-abc123"
3. Update the sha256. The easiest way to do this is to comment out the line, then Bazel will print a message with the correct value.
4. load("@bazel_lib//:deps.bzl", "go_dependencies") and then call go_dependencies()

Note that GitHub source archives don't have a strong guarantee on the sha256 stability, see https://github.blog/2023-02-21-update-on-the-future-stability-of-source-code-archives-and-hashes