build/bazel/scripts/update_bazel_vendor_dir.py

#!/usr/bin/env fuchsia-vendored-python

# Copyright 2025 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import argparse
import shutil
import subprocess
import sys
import tempfile
from pathlib import Path


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--bazel",
        type=Path,
        required=True,
        help="Path to Bazel executable",
    )
    parser.add_argument(
        "--workspace",
        type=Path,
        required=True,
        help="Path to Bazel workspace",
    )
    parser.add_argument(
        "--bazel-vendor-dir",
        type=Path,
        required=True,
        help="Bazel vendor directory to write to",
    )
    parser.add_argument(
        "--repo",
        action="append",
        required=True,
        help="Bazel repositories to vendor",
    )
    parser.add_argument(
        "--stub-repo",
        action="append",
        required=True,
        help=(
            "Bazel repositories that are manually stubbed out, their existing"
            " content should be preserved after the update"
        ),
    )
    args = parser.parse_args()

    # Always do a clean vendor in a temporary directory to drop unwanted repos.
    with tempfile.TemporaryDirectory() as tmp:
        temp_dir = Path(tmp)
        cmd = [
            args.bazel,
            "vendor",
            f"--vendor_dir={temp_dir}",
            # Overwrite local-only settings from bazelrc. Allow network access and
            # enable Bazel Central repository when updating vendor repositories.
            "--downloader_config=/dev/null",
            "--registry=https://bcr.bazel.build/",
        ]
        cmd += [f"--repo={repo}" for repo in args.repo]

        print(" ".join(str(s) for s in cmd))

        # Remove the existing local Bazel registry to force `bazel vendor` to update
        # and create a new one.
        shutil.rmtree(args.bazel_vendor_dir / "_registries", ignore_errors=True)
        subprocess.check_call(
            cmd,
            cwd=args.workspace,
        )

        # Pin all the vendored and stub directories, to make sure Bazel doesn't try
        # to update any of them when building.
        with open(temp_dir / "VENDOR.bazel", "w") as f:
            f.write(
                """################################################################################
# @generated
# DO NOT MODIFY: This file is auto-generated by the following command, instead
# of changing this file directly, rerun this command:
#
#    fx update-bazel-vendor-dir
################################################################################

"""
            )
            for repo in sorted(args.repo + args.stub_repo):
                f.write(f'pin("{repo}")\n')

        # Vendor again after all repositories are pinned to drop the `.marker` files.
        # This also verifies the VENDOR.bazel file re-written above is valid.
        subprocess.check_call(
            cmd,
            cwd=args.workspace,
            # Suppress stdout and stderr to avoid user confusion.
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )

        # Persist manually stubbed repos from the existing vendor dir.
        for repo in args.stub_repo:
            repo_name = repo.lstrip("@")
            shutil.copytree(
                args.bazel_vendor_dir / repo_name, temp_dir / repo_name
            )
        shutil.move(args.bazel_vendor_dir / "README.md", temp_dir / "README.md")
        shutil.move(args.bazel_vendor_dir / "OWNERS", temp_dir / "OWNERS")

        shutil.rmtree(args.bazel_vendor_dir)
        shutil.move(temp_dir, args.bazel_vendor_dir)


if __name__ == "__main__":
    sys.exit(main())