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A useful skeleton template for Python command-line applications, which sets up logging and provides useful command-line options to control it.
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| #!/usr/bin/env python3 | |
| import argparse | |
| import logging | |
| import logging.config | |
| import logging.handlers | |
| import os | |
| import sys | |
| from typing import Any | |
| CONSOLE_LOG_FORMAT = "%(asctime)s.%(msecs)03d [%(levelname)s] --- %(message)s" | |
| CONSOLE_TIME_FORMAT = "%H:%M:%S" | |
| def get_argument_parser() -> argparse.ArgumentParser: | |
| """Set up command-line argument parser.""" | |
| prog_name = os.path.basename(sys.argv[0]) or "app.py" | |
| parser = argparse.ArgumentParser(prog=prog_name) | |
| parser.add_argument( | |
| "-d", | |
| "--debug", | |
| dest="log_level", | |
| action="store_const", | |
| const=logging.DEBUG, | |
| help="Show debug output", | |
| ) | |
| parser.add_argument("-l", "--log-file", help="Log to file instead of console") | |
| parser.add_argument( | |
| "-q", | |
| "--quiet", | |
| dest="log_level", | |
| action="store_const", | |
| const=logging.WARNING, | |
| help="Show only warnings and errors", | |
| ) | |
| parser.set_defaults(log_level=logging.INFO, log_file=None) | |
| return parser | |
| # -------- MAIN APPLICATION | |
| def application_main(args: argparse.Namespace) -> int: | |
| """Application main entrypoint.""" | |
| return 0 | |
| # -------- END MAIN APPLICATION | |
| def get_logging_config(args: argparse.Namespace) -> None: | |
| """Configure logging based on command-line parameters.""" | |
| # Basic logging configuration skeleton | |
| config_dict: dict[str, Any] = { | |
| "version": 1, | |
| "formatters": { | |
| "console": {"format": CONSOLE_LOG_FORMAT, "datefmt": CONSOLE_TIME_FORMAT}, | |
| "logfile": {"format": "%(asctime)s %(name)s %(levelname)s: %(message)s"}, | |
| }, | |
| "handlers": {}, | |
| "root": {"level": 0, "handlers": []}, | |
| } | |
| # Customise logging configuration based on command-line arguments. | |
| if args.log_file is None: | |
| config_dict["handlers"]["console"] = { | |
| "class": "logging.StreamHandler", | |
| "formatter": "console", | |
| "level": args.log_level, | |
| "stream": "ext://sys.stdout", | |
| } | |
| config_dict["root"]["handlers"].append("console") | |
| else: | |
| config_dict["handlers"]["logfile"] = { | |
| "class": "logging.handlers.TimedRotatingFileHandler", | |
| "formatter": "logfile", | |
| "level": args.log_level, | |
| "filename": args.log_file, | |
| "when": "midnight", | |
| "backupCount": 30, | |
| } | |
| config_dict["root"]["handlers"].append("logfile") | |
| # Implement configuration | |
| logging.config.dictConfig(config_dict) | |
| def main(argv: list[str]) -> int: | |
| """Initialise logging and parse command-line arguments.""" | |
| # Default logging so we can start logging straight away | |
| logging.basicConfig( | |
| format=CONSOLE_LOG_FORMAT, datefmt=CONSOLE_TIME_FORMAT, level=logging.INFO | |
| ) | |
| parser = get_argument_parser() | |
| args = parser.parse_args(args=argv[1:]) | |
| get_logging_config(args) | |
| return application_main(args) | |
| if __name__ == "__main__": | |
| sys.exit(main(sys.argv)) |
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