dist/dist.bzl

# Rule to support Bazel in copying its output files to the dist dir outside of
# the standard Bazel output user root.

load("@bazel_skylib//rules:copy_file.bzl", "copy_file")

def _label_list_to_manifest(lst):
    """Convert the outputs of a label list to manifest content."""
    all_dist_files = []
    for f in lst:
        all_dist_files += f[DefaultInfo].files.to_list()
    return all_dist_files, "\n".join([dist_file.short_path for dist_file in all_dist_files])

def _generate_dist_manifest_impl(ctx):
    # Create a manifest of dist files to differentiate them from other runfiles.
    dist_manifest = ctx.actions.declare_file(ctx.attr.name + "_dist_manifest.txt")
    all_dist_files, dist_manifest_content = _label_list_to_manifest(ctx.attr.data)
    ctx.actions.write(
        output = dist_manifest,
        content = dist_manifest_content,
    )

    dist_archives_manifest = ctx.actions.declare_file(ctx.attr.name + "_dist_archives_manifest.txt")
    all_dist_archives, dist_archives_manifest_content = _label_list_to_manifest(ctx.attr.archives)
    ctx.actions.write(
        output = dist_archives_manifest,
        content = dist_archives_manifest_content,
    )

    # Create the runfiles object.
    runfiles = ctx.runfiles(files = all_dist_files + all_dist_archives + [
        dist_manifest,
        dist_archives_manifest,
    ])

    return [DefaultInfo(runfiles = runfiles)]

_generate_dist_manifest = rule(
    implementation = _generate_dist_manifest_impl,
    doc = """Generate a manifest of files to be dist to a directory.""",
    attrs = {
        "data": attr.label_list(
            mandatory = True,
            allow_files = True,
            doc = """Files or targets to copy to the dist dir.

In the case of targets, the rule copies the list of `files` from the target's DefaultInfo provider.
""",
        ),
        "archives": attr.label_list(
            mandatory = True,
            allow_files = [".tar.gz", ".tar"],
            doc = """Files or targets to be extracted to the dist dir.

In the case of targets, the rule copies the list of `files` from the target's DefaultInfo provider.
""",
        ),
    },
)

def copy_to_dist_dir(name, data = [], archives = []):
    """A dist rule to copy files out of Bazel's output directory into a custom location.

    Example:
    ```
    bazel run //path/to/my:dist_target -- --dist_dir=/tmp/dist
    ```

    Args:
        name: name of this rule
        data: A list of labels, whose outputs are copied to `--dist_dir`.
        archives: A list of labels, whose outputs are treated as tarballs and
          extracted to `--dist_dir`.
    """
    _generate_dist_manifest(
        name = name + "_dist_manifest",
        data = data,
        archives = archives,
    )

    copy_file(
        name = name + "_dist_tool",
        src = "//build/bazel_common_rules/dist:dist.py",
        out = name + "_dist.py",
    )

    # The dist py_binary tool must be colocated in the same package as the
    # dist_manifest so that the runfiles directory is the same, and that the
    # dist_manifest is in the data runfiles of the dist tool.
    native.py_binary(
        name = name,
        main = name + "_dist.py",
        srcs = [name + "_dist.py"],
        python_version = "PY3",
        visibility = ["//visibility:public"],
        data = [name + "_dist_manifest"],
    )