Python: Create a Logger

(Last Updated On: )

This post is how-to create a logger.

First we need to import

  1. import sys
  2. import logging
  3. from datetime import datetime
  4. from pytz import timezone

Then we create a class for Formatter

  1. class CustomFormatter(logging.Formatter):
  2.     grey = "\x1b[38;20m"
  3.     reset = "\x1b[0m"
  4.     format = "%(asctime)s - %(name)s - %(levelname)s - %(message)s (%(filename)s:)"
  5.     FORMATS = {
  6.         logging.DEBUG: '\x1b[38;5;23m' + format + reset,
  7.         logging.INFO: grey + format + reset,
  8.         logging.WARNING: '\x1b[38;5;56m' + format + reset,
  9.         logging.ERROR: '\x1b[38;5;197m' + format + reset,
  10.         logging.CRITICAL: '\x1b[38;5;1m' + format +reset
  11.     }
  12.  
  13.     def format(self, record):
  14.         log_fmt = self.FORMATS.get(record.levelno)
  15.         formatter = logging.Formatter(log_fmt)
  16.         return formatter.format(record)

Then we create a function set our logger up.

  1. def set_logger(logging_level, name, log_dir, timezone):
  2.     LOGGING_LEVELS = ['WARNING','INFO','DEBUG','ERROR']
  3.     if logging_level not in LOGGING_LEVELS:
  4.         logging_level = 'INFO'
  5.  
  6.     level_lookup = {
  7.         'WARNING': logging.WARNING,
  8.         'INFO': logging.INFO,
  9.         'DEBUG': logging.DEBUG,
  10.         'ERROR': logging.ERROR,
  11.     }
  12.     logging.Formatter.converter = lambda *args: datetime.now(tz=timezone(timezone)).timetuple()
  13.     logging.basicConfig(level=level_lookup[logging_level], format="[%(levelname)s] %(asctime)s - %(message)s:%(lineno)d")
  14.     stream_handler = logging.StreamHandler(sys.stdout)
  15.     stream_handler.setFormatter(CustomFormatter())
  16.     logger = logging.getLogger(name)
  17.     logger.addHandler(stream_handler)
  18.     logger.setLevel(logging_level)
  19.  
  20.     Path(log_dir).mkdir(parents=True, exist_ok=True)
  21.  
  22.     now = datetime.now(tz=timezone(timezone))
  23.     now = now.strftime("%H-%M-%S")
  24.  
  25.     log_file = '%slog_%s.log' % (log_dir, now)
  26.     file_handler = logging.FileHandler(log_file, mode='a')
  27.     file_handler.setFormatter(logging.Formatter("[%(levelname)s] %(asctime)s - %(message)s:%(lineno)d"))
  28.     logger.addHandler(file_handler)
  29.  
  30.     return logger

References

https://alexandra-zaharia.github.io/posts/make-your-own-custom-color-formatter-with-python-logging/