config.py

#!/usr/bin/env python
import sys
import logging
import logging.handlers


# The terminal has 8 colors with codes from 0 to 7
BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = range(8)

# These are the sequences need to get colored ouput
RESET_SEQ = "\033[0m"
COLOR_SEQ = "\033[1;%dm"
BOLD_SEQ = "\033[1m"

# The background is set with 40 plus the number of the color,
# and the foreground with 30
COLORS = {
    'WARNING':  COLOR_SEQ % (30 + YELLOW) + 'WARN ' + RESET_SEQ,
    'INFO':     COLOR_SEQ % (30 + WHITE) + 'INFO ' + RESET_SEQ,
    'DEBUG':    COLOR_SEQ % (30 + BLUE) + 'DEBUG' + RESET_SEQ,
    'CRITICAL': COLOR_SEQ % (30 + YELLOW) + 'CRITI' + RESET_SEQ,
    'ERROR':    COLOR_SEQ % (30 + RED) + 'ERROR' + RESET_SEQ,
}


class ColoredFormatter(logging.Formatter):
    def __init__(self, msg, use_color=True):
        logging.Formatter.__init__(self, msg)
        self.use_color = use_color

    def format(self, record):
        if self.use_color:
            record.levelname = COLORS.get(record.levelname, record.levelname)
        return logging.Formatter.format(self, record)


class LoggingConfiguration(object):
    COLOR_FORMAT = "%(asctime)s" + \
                   " %(levelname)s %(message)s " + \
                   "(" + BOLD_SEQ + "%(filename)s" + RESET_SEQ + ":%(lineno)d)"
    NO_COLOR_FORMAT = "%(asctime)s %(levelname)s " + \
                      "%(message)s " + \
                      "(%(filename)s:%(lineno)d)"
    FILE_FORMAT = "%(asctime)s %(levelname)s " + \
                  "%(message)s "

    @classmethod
    def set(cls, log_level, log_filename, append=None, **kwargs):
        """ Configure a rotating file logging
        """
        logger = logging.getLogger()
        logger.setLevel(log_level)

        COLOR_FORMAT = cls.COLOR_FORMAT
        NO_COLOR_FORMAT = cls.NO_COLOR_FORMAT
        FILE_FORMAT = cls.FILE_FORMAT
        if 'name' in kwargs:
            COLOR_FORMAT = COLOR_FORMAT.replace('%(threadName)-22s',
                                                '%-22s' % (kwargs['name']))
            NO_COLOR_FORMAT = NO_COLOR_FORMAT.replace(
                '%(threadName)-22s', '%-22s' % (kwargs['name']))
            FILE_FORMAT = FILE_FORMAT.replace(
                '%(threadName)-22s', '%s' % (kwargs['name']))

        # Log to rotating file
        try:
            fh = logging.handlers.RotatingFileHandler(
                log_filename,
                mode='a+',
                backupCount=3
            )
            fh.setFormatter(ColoredFormatter(FILE_FORMAT, False))
            fh.setLevel(log_level)
            logger.addHandler(fh)
            if not append:
                # Create a new log file on every new
                fh.doRollover()
        except IOError as e:
            print('ignore to log to {}: {}'.format(log_filename, e))

        # Log to sys.stderr using log level passed through command line
        if log_level != logging.NOTSET:
            log_handler = logging.StreamHandler(sys.stdout)
            if sys.platform.find('linux') >= 0:
                formatter = ColoredFormatter(COLOR_FORMAT)
            else:
                formatter = ColoredFormatter(NO_COLOR_FORMAT, False)
            log_handler.setFormatter(formatter)
            log_handler.setLevel(log_level)
            logger.addHandler(log_handler)