Python colorful logging example

README.md

Usage example

% python -i colorful_logging_formatter.py 
>>> import logging
>>> logger = logging.getLogger('foo')
>>> logger.setLevel(logging.DEBUG)
>>> import sys
>>> handler = logging.StreamHandler(sys.stderr)
>>> handler.setFormatter(ColorLogFormatter())
>>> handler.setLevel(logging.DEBUG)
>>> logger.addHandler(handler)
>>> 
>>> logger.debug('Debug message')
 DEBUG   foo  Debug message
>>> logger.info('Info message')
 INFO    foo  Info message
>>> logger.warning('Warning message')
 WARNING  foo  Warning message
>>> logger.error('Error message')
 ERROR   foo  Error message
>>> logger.critical('Critical message')
 CRITICAL  foo  Critical message
>>> try:
...     100 / 0
... except:
...     logger.exception('Something bad happened!')
... 
 ERROR   foo  Something bad happened!
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
ZeroDivisionError: integer division or modulo by zero
>>> 

Screenshot

Note

To see it in all its glory, you'll need to use a powerline-patched font in your terminal (I use inconsolata-dz). Otherwise, just set POWERLINE_STYLE = False.

colorful_logging_formatter.py

import logging
from termcolor import colored

POWERLINE_STYLE = True

class ColorLogFormatter(logging.Formatter):
    level_colors = {
        logging.DEBUG: 'cyan',
        logging.INFO: 'green',
        logging.WARNING: 'yellow',
        logging.ERROR: 'red',
        logging.CRITICAL: 'red',
    }

    def _get_exc_info(self, record):
        if record.exc_info:
            # Cache the traceback text to avoid converting it multiple times
            # (it's constant anyway)
            if not record.exc_text:
                record.exc_text = self.formatException(record.exc_info)
        if record.exc_text:
            try:
                return unicode(record.exc_text)
            except UnicodeError:
                # Sometimes filenames have non-ASCII chars, which can lead
                # to errors when s is Unicode and record.exc_text is str
                # See issue 8924.
                # We also use replace for when there are multiple
                # encodings, e.g. UTF-8 for the filesystem and latin-1
                # for a script. See issue 13232.
                return record.exc_text.decode(sys.getfilesystemencoding(),
                                              'replace')
        return None

    def format(self, record):
        """Format logs nicely"""

        color = self.level_colors.get(record.levelno, 'white')

        levelname = colored(' {0:<6} '.format(record.levelname),
                            color, attrs=['reverse'])

        if POWERLINE_STYLE:
            levelname += colored(u'\ue0b0', color, 'on_white')

        loggername = colored(' {0} '.format(record.name), 'red', 'on_white')

        if POWERLINE_STYLE:
            loggername += colored(u'\ue0b0', 'white')

        message = colored(record.getMessage(), color)

        s = ' '.join((''.join((levelname, loggername)), message))

        exc_info = self._get_exc_info(record)
        if exc_info is not None:
            if s[-1:] != "\n":
                s = s + "\n"
            s += colored(exc_info, 'grey', attrs=['bold'])

        return s