Here's a JSON log formatter for Python. I want to be able to log details of exceptions (and have some capability to debug-by-logs). I want to be able to log extra data in JSON format (in addition to a message string).

Is my approach sound, in general?

I distinguish between regular logging and exception logging by checking for presence of exc_info. It works, but is it the right way to do it?

Am logging the exception info that I should be logging? Am I missing anything useful?

Here's what I wrote so far. (Work in progress, and I'm not married to this design.)

class JsonLogFormatter(logging.Formatter):
	def __init__(self) -> None:
		super().__init__()

	def format(self, record):
		log_record_dict = { "time": self.formatTime(record), "level": record.levelname, "message": record.message }

		if record.exc_info is not None:
			log_record_dict.update( {"exception": self.formatException(record.exc_info)} )
		
		log_record_dict.update(record.args)
		return json.dumps(log_record_dict, indent=None)

Log entry in the unhandled exception hook.

class UncaughtExceptionHook:

	def __init__(self, logger):
		self.logger = logger
		sys.excepthook = self.exception_hook    # It seemd sonvenient to register the hook with the system in the ctor.  Future will show if this is future-proof.

	def exception_hook(self, ex_type, ex_value, ex_traceback):
		self.logger.critical(f"Unhandled exception.",  exc_info=(ex_type, ex_value, ex_traceback))
		sys.exit(1)

Calling code.

logger.info("hello JSON log entry")
logger.info("now with an attachment", {"foo": "Lorem ipsum"} )

#deliberate exception to check the UncaughtExceptionHook
raise ValueError("deliberate exception to check the UncaughtExceptionHook" )

Resulting log entries.

{"time": "2023-05-02 15:12:46,735", "level": "INFO", "message": "hello JSON log entry"}
{"time": "2023-05-02 15:12:53,643", "level": "INFO", "message": "now with an attachment", "foo": "Lorem ipsum"}
{"time": "2023-05-02 15:12:56,086", "level": "CRITICAL", "message": "Unhandled exception.", "exception": "Traceback (most recent call last):\n  File \"C:\\Program Files\\WindowsApps\\PythonSoftwareFoundation.Python.3.11_3.11.1008.0_x64__qbz5n2kfra8p0\\Lib\\runpy.py\", line 198, in _run_module_as_main\n    return _run_code(code, main_globals, None,\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"C:\\Program Files\\WindowsApps\\PythonSoftwareFoundation.Python.3.11_3.11.1008.0_x64__qbz5n2kfra8p0\\Lib\\runpy.py\", line 88, in _run_code\n    exec(code, run_globals)\n  File \"c:\\Users\\User\\.vscode\\extensions\\ms-python.python-2023.6.1\\pythonFiles\\lib\\python\\debugpy\\adapter/../..\\debugpy\\launcher/../..\\debugpy\\__main__.py\", line 39, in <module>\n    cli.main()\n  File \"c:\\Users\\User\\.vscode\\extensions\\ms-python.python-2023.6.1\\pythonFiles\\lib\\python\\debugpy\\adapter/../..\\debugpy\\launcher/../..\\debugpy/..\\debugpy\\server\\cli.py\", line 430, in main\n    run()\n  File \"c:\\Users\\User\\.vscode\\extensions\\ms-python.python-2023.6.1\\pythonFiles\\lib\\python\\debugpy\\adapter/../..\\debugpy\\launcher/../..\\debugpy/..\\debugpy\\server\\cli.py\", line 284, in run_file\n    runpy.run_path(target, run_name=\"__main__\")\n  File \"c:\\Users\\User\\.vscode\\extensions\\ms-python.python-2023.6.1\\pythonFiles\\lib\\python\\debugpy\\_vendored\\pydevd\\_pydevd_bundle\\pydevd_runpy.py\", line 321, in run_path\n    return _run_module_code(code, init_globals, run_name,\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"c:\\Users\\User\\.vscode\\extensions\\ms-python.python-2023.6.1\\pythonFiles\\lib\\python\\debugpy\\_vendored\\pydevd\\_pydevd_bundle\\pydevd_runpy.py\", line 135, in _run_module_code\n    _run_code(code, mod_globals, init_globals,\n  File \"c:\\Users\\User\\.vscode\\extensions\\ms-python.python-2023.6.1\\pythonFiles\\lib\\python\\debugpy\\_vendored\\pydevd\\_pydevd_bundle\\pydevd_runpy.py\", line 124, in _run_code\n    exec(code, run_globals)\n  File \"C:\\Users\\User\\source\\repos\\KiCAD netlist reader\\test01.py\", line 59, in <module>\n    raise ValueError(\"deliberate exception to check the UncaughtExceptionHook\" )\nValueError: deliberate exception to check the UncaughtExceptionHook"}

posted 12 months ago

CC BY-NC 4.0

12mo ago

misk94555‭

31 reputation 1 0 6 1