coloured_stream_handler.py: A logging stream handler that colours lines differently depending on their logging level.

coloured_stream_handler.py

from logging import StreamHandler

try:
    unicode
    _unicode = True
except NameError:
    _unicode = False
    
    
class ColouredStreamHandler(StreamHandler):

    COLOURS = {
        0: '37',        # not set
        10: '37',       # debug
        20: '39',       # info
        30: '33',       # warning
        40: '31',       # error
        50: '31;1'      # critical
    }

    def __init__(self):
        super(ColouredStreamHandler, self).__init__()

    def emit(self, record):
        try:
            msg = self.format(record)
            stream = self.stream
            fs = "\033[" + self.COLOURS[record.levelno] + "m%s\033[0m\n"
            if not _unicode:
                stream.write(fs % msg)
            else:
                try:
                    if (isinstance(msg, unicode) and getattr(stream, 'encoding', None)):
                        ufs = u'%s\n'
                        try:
                            stream.write(ufs % msg)
                        except UnicodeEncodeError:
                            stream.write((ufs % msg).encode(stream.encoding))
                    else:
                        stream.write(fs % msg)
                except UnicodeError:
                    stream.write(fs % msg.encode("UTF-8"))
            self.flush()
        except (KeyboardInterrupt, SystemExit):
            raise
        except:
            self.handleError(record)