Colored formatter for logging in python. Supports logging to a file without the escape sequences.

colored_log.py

#!/usr/bin/env python

#  Copyright (c) 2017 Kurt Jacobson

#  Permission is hereby granted, free of charge, to any person obtaining a copy
#  of this software and associated documentation files (the "Software"), to deal
#  in the Software without restriction, including without limitation the rights
#  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#  copies of the Software, and to permit persons to whom the Software is
#  furnished to do so, subject to the following conditions:

#  The above copyright notice and this permission notice shall be included in all
#  copies or substantial portions of the Software.

#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
#  SOFTWARE.

from copy import copy
from logging import Formatter

MAPPING = {
    'DEBUG'   : 37, # white
    'INFO'    : 36, # cyan
    'WARNING' : 33, # yellow
    'ERROR'   : 31, # red
    'CRITICAL': 41, # white on red bg
}

PREFIX = '\033['
SUFFIX = '\033[0m'

class ColoredFormatter(Formatter):

    def __init__(self, patern):
        Formatter.__init__(self, patern)

    def format(self, record):
        colored_record = copy(record)
        levelname = colored_record.levelname
        seq = MAPPING.get(levelname, 37) # default white
        colored_levelname = ('{0}{1}m{2}{3}') \
            .format(PREFIX, seq, levelname, SUFFIX)
        colored_record.levelname = colored_levelname
        return Formatter.format(self, colored_record)


# ********* Example Usage *********

def demo():

    import logging

    # Create logger
    log = logging.getLogger(__name__)

    # Add console handler
    ch = logging.StreamHandler()
    ch.setLevel(logging.DEBUG)
    cf = ColoredFormatter("[%(name)s][%(levelname)s]  %(message)s (%(filename)s:%(lineno)d)")
    ch.setFormatter(cf)
    log.addHandler(ch)

    # Add file handler
    fh = logging.FileHandler('demo.log')
    fh.setLevel(logging.DEBUG)
    ff = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
    fh.setFormatter(ff)
    log.addHandler(fh)

    # Set log level
    log.setLevel(logging.DEBUG)

    # Log some stuff
    log.debug("Logging demo has started")
    log.info("Logging to 'demo.log' in the script dir")
    log.warning("This is my last warning, take heed")
    log.error("This is an error")
    log.critical("He's dead, Jim")

if __name__ == '__main__':
    demo()