logging formats based on log levels

custom_format_logger.py

import logging
from bisect import bisect
from logging import getLogger, Formatter, LogRecord, StreamHandler
from typing import Dict


class LevelFormatter(Formatter):
    def __init__(self, formats: Dict[int, str], **kwargs):
        super().__init__()

        if 'fmt' in kwargs:
            raise ValueError(
                'Format string must be passed to level-surrogate formatters, '
                'not this one'
            )

        self.formats = sorted(
            (level, Formatter(fmt, **kwargs)) for level, fmt in formats.items()
        )

    def format(self, record: LogRecord) -> str:
        idx = bisect(self.formats, (record.levelno,), hi=len(self.formats)-1)
        level, formatter = self.formats[idx]
        return formatter.format(record)


def test():
    handler = StreamHandler()
    handler.setFormatter(
        LevelFormatter(
            {
                logging.INFO: '%(levelname)s (info): %(message)s',
                logging.WARNING: '%(levelname)s: (warning): %(message)s',
            }
        )
    )
    handler.setLevel(logging.DEBUG)

    logger = getLogger('test_logger')
    logger.setLevel(logging.DEBUG)
    logger.addHandler(handler)

    logger.debug('mdebug')
    logger.info('minfo')
    logger.log(logging.INFO + 1, 'higher minfo')
    logger.warning('mwarning')
    logger.error('merror')
    logger.critical('mcritical')


test()