ColoredFormatter is a formatter for use with pythons logging module.

It allows colors to be placed in the format string, which is mostly useful when paired with a StreamHandler that is outputting to a terminal. This is accomplished by added a set of terminal color codes to the record before it is used to format the string.

The following values are made availible for use in the format string:

• fg_{colorname}, bg_{colorname}: Foreground and background colors. The colors names are black, red, green, yellow, blue, purple, cyan and white.
• bold: Bold output.
• reset: Clear all formatting (both foreground and background colors).
• log_color: Return the color associated with the records level (from color_levels).

ColoredFormatter takes several arguments:

• format: The format string used to output the message (required).
• datefmt: An optional date format passed to the base class. See logging.Formatter.
• reset: Implicitly adds a color reset code to the message output, unless the output already ends with one. Defaults to True.
• log_colors: A mapping of record level names to color names. The defaults can be found in colorlog.default_log_colors, or the below example.
• style: Availible on Python 3.2 and above. See logging.Formatter.

The following code creates a ColoredFormatter for use in a logging setup, passing each arguments defaults to the constructor:

from colorlog import ColoredFormatter

formatter = ColoredFormatter(
        "%(log_color)s%(levelname)-8s%(reset)s %(blue)s%(message)s",
        datefmt=None,
        reset=True,
        color_levels={
                'DEBUG':    'cyan',
                'INFO':     'green',
                'WARNING':  'yellow',
                'ERROR':    'red',
                'CRITICAL': 'red',
        }
)

logging.config.dictConfig({
        'formatters': {
                'colored': {
                        '()': 'colorlog.ColoredFormatter',
                        'format': "%(log_color)s%(levelname)-8s%(reset)s %(blue)s%(message)s"
                }
        },

        ...
})

A full example dictionary can be found in tests/test_colorlog.py.

...

[formatters]
keys=color

[formatter_color]
class=colorlog.ColoredFormatter
format=%(log_color)s%(levelname)-8s%(reset)s %(bg_blue)s[%(name)s]%(reset)s %(message)s from fileConfig
datefmt=%m-%d %H:%M:%S

...

An instance of ColoredFormatter created with those arguments will then be used by any handlers that are configured to use the color formatter.

A full example configuration can be found in tests/test_config.ini.

colorlog works on Python 2.6 and above, including Python 3.

Tests similar to those in the above examples can be found in tests/test_colorlog.py, which can also be run with any supported version of Python.

colorlog is distributed under the MIT Licence.