portage/tools/generate_chrome_prebuilt_config.py

#!/usr/bin/env python3
# Copyright 2023 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""A tool to generate bazel config to use a prebuilt for chromeos-chrome."""

import logging
import os
import re
import subprocess


def _run_command(args: list[str]) -> str:
    """Runs the specified command and returns its output."""
    return subprocess.check_output(args, encoding="utf-8")


def _resolve_alias(label: str) -> str:
    """Resolves the specified Bazel alias and returns its actual label."""
    while True:
        actual = _run_command(
            ["bazel", "query", f"labels('actual', {label})"]
        ).strip()
        if actual == "":
            return label
        label = actual


def _get_chromeos_version_sh_path() -> str:
    """Returns the path of the chromeos_version.sh file."""
    return os.path.join(
        _run_command(["bazel", "info", "workspace"]).strip(),
        "third_party/chromiumos-overlay/chromeos/config/chromeos_version.sh",
    )


def _get_chromeos_version_info() -> dict[str, str]:
    """Returns ChromeOS version info."""
    result = {}
    for line in _run_command([_get_chromeos_version_sh_path()]).split("\n"):
        m = re.match(r"(\w+)=(.*)", line.strip())
        if m:
            result[m.group(1)] = m.group(2)
    return result


def _find_chrome_prebuilt(board: str, branch: int, build: int) -> str:
    """Finds a chromeos-chrome prebuilt and returns its URL."""

    # Try up to 10 versions.
    for _ in range(10):
        logging.info(
            "Trying to find a prebuilt: branch = %i, build = %i", branch, build
        )
        try:
            output = _run_command(
                [
                    "gsutil",
                    "ls",
                    f"gs://chromeos-prebuilt/board/{board}/postsubmit-R{branch}-{build}*/packages/chromeos-base/chromeos-chrome*.tbz2",
                ]
            )
            return output.strip().splitlines()[-1]
        except subprocess.CalledProcessError:
            # Failed to find a usable prebuilt. Try an older version.
            build = build - 1
    raise RuntimeError("Failed to find a prebuilt.")


def main():
    """The entry point of the program."""

    logging.basicConfig(level=logging.INFO)

    board = os.environ["BOARD"]
    logging.info("Board name is %s", board)

    version_info = _get_chromeos_version_info()
    branch = int(version_info["CHROME_BRANCH"])
    build = int(version_info["CHROMEOS_BUILD"])
    logging.info(
        "Version numbers taken from the checkout: branch = %i, build = %i",
        branch,
        build,
    )

    chrome_label = "@portage//chromeos-base/chromeos-chrome"
    chrome_actual_label = _resolve_alias(chrome_label)
    prebuilt_label = chrome_actual_label + "_prebuilt"
    logging.info("Prebuilt label is %s", prebuilt_label)

    prebuilt_url = _find_chrome_prebuilt(board, branch, build)

    print(f"--{prebuilt_label}={prebuilt_url}")


if __name__ == "__main__":
    main()