Chroma Formatter

Wrapper for Python logging formatter that adds color

Installation

Chroma Formatter is on PyPI and can be installed with:

pip install chromaformatter

Usage

Chroma Formatter adds two features to the default logging formatter, colors can be added to the log format string, and formatted arguments in a log message can be colored. Colors can be inserted info the format string as such:

log_format = (
    f'{Colors.Fore.GREEN}%(asctime)-s '
    f'{Colors.LEVEL_COLOR}%(levelname).1s '
    f'{Colors.Fore.MAGENTA}%(filename)-s:%(lineno)03d '
    f'{Colors.LEVEL_COLOR}- %(message)s'
)

Then, use chromaformatter.ChromaFormatter rather than logging.Formatter.

import sys
import logging

from chromaformatter import ChromaFormatter, Colors

log = logging.getLogger()
log_format = (
    f'{Colors.Fore.GREEN}%(asctime)-s '
    f'{Colors.LEVEL_COLOR}%(levelname).1s '
    f'{Colors.Fore.MAGENTA}%(filename)-s:%(lineno)03d '
    f'{Colors.LEVEL_COLOR}- %(message)s'
)
formatter = ChromaFormatter(
    fmt=log_format,
    arg_start_color=Colors.Fore.WHITE,
    arg_end_color=Colors.LEVEL_COLOR
)
handler = logging.StreamHandler(stream=sys.stdout)
handler.setFormatter(formatter)
log.addHandler(handler)

Formatted Arguments in a Log

By setting arg_start_color for argument colors and arg_end_color for the rest of the string that comes after the argument, those colors will be applied to arguments.

log.info('This %s will be colored.', 'variable')

Additional Configuration

ChromaFormatter has a dict called color_map to determine the colors of each logging level.

By default, the colors are:

Color map can be changed as such:

formatter.color_map[logging.INFO] = Colors.Fore.WHITE
formatter.color_map[logging.DEBUG] = Colors.Fore.MAGENTA

Applying to Existing Loggers

If you are using a third party module that uses the standard python logging module you can apply a ChromaFormatter as such:

import sys
import logging

from chromaformatter import ChromaFormatter, Colors

log_format = (
    f'{Colors.Fore.GREEN}%(asctime)-s '
    f'{Colors.LEVEL_COLOR}%(levelname).1s '
    f'{Colors.Fore.MAGENTA}%(filename)-s:%(lineno)03d '
    f'{Colors.LEVEL_COLOR}- %(message)s'
)
stream_formatter = ChromaFormatter(log_format)
stream_handler = logging.StreamHandler(stream=sys.stdout)

flask_logger = logging.getLogger('werkzeug')
while flask_logger.handlers:
    flask_logger.removeHandler(flask_logger.handlers.pop())
flask_logger.addHandler(stream_handler)