def start()

in skywalking/bootstrap/cli/sw_python.py [0:0]

• 30 lines of code
• 5 McCabe index (conditional complexity)

def start() -> None:
    """ Entry point of CLI """
    parser = argparse.ArgumentParser(description='SkyWalking Python Agent CLI',
                                     epilog='Append your command, with SkyWalking agent attached for you automatically',
                                     allow_abbrev=False)

    parser.add_argument('-d', '--debug', help='Print CLI debug logs to stdout', action='store_true')

    base_subparser = argparse.ArgumentParser(add_help=False)
    subparsers = parser.add_subparsers(dest='option', required=True, help='CLI options, now only supports `run`, for '
                                                                          'help please type `sw-python -h` or refer '
                                                                          'to the CLI documentation')

    run_parser = subparsers.add_parser('run', parents=[base_subparser])

    # TODO support parsing optional sw_config.toml
    # config_parser = subparsers.add_parser("config", parents=[base_subparser])
    # parser.add_argument('-config', nargs='?', type=argparse.FileType('r'),
    #                     help='Optionally takes a sw_python.toml config file')

    run_parser.add_argument('-p', '--prefork', help='[Experimental] This flag turns on auto detection of '
                                                    'uwsgi and gunicorn, '
                                                    'then automatically starts the Python agent in each worker process.'
                                                    "(TL;DR: You don't need to add manual "
                                                    '@postfork hook to your app anymore)',
                            action='store_true')
    # The command arg compress all remaining args into itself
    # This must be the last arg
    run_parser.add_argument('command', help='Your original commands e.g. gunicorn app.wsgi',
                            nargs=argparse.REMAINDER, metavar='command')

    # To handle cases with flags and positional args in user commands
    args = parser.parse_args()  # type: argparse.Namespace

    cli_logger.setLevel(logging.DEBUG if args.debug else logging.INFO)

    cli_logger.debug(f'Args received {args}')

    if not args.command:
        cli_logger.error('Command is not provided, please type `sw-python -h` for the list of command line arguments')
        return
    try:
        dispatch(args)
    except SWRunnerFailure:
        cli_logger.exception(f"Failed to run the given user application command `{' '.join(args.command)}`, "
                             f'please make sure given command is valid.')
        return