Structlog key value renderer with colors

colorkeyvaluerender.py

# coding: utf-8
'Color key value renderer'

import itertools
from io import StringIO

import colorama
import structlog

LEVEL_COLORS = {
    'critical': colorama.Fore.RED,
    'exception': colorama.Fore.RED,
    'error': colorama.Fore.RED,
    'warn': colorama.Fore.YELLOW,
    'warning': colorama.Fore.YELLOW,
    'info': colorama.Fore.GREEN,
    'debug': colorama.Fore.BLUE,
    'notset': colorama.Back.RED,
}

COLORS = {
    'timestamp': colorama.Style.DIM,
    'time': colorama.Style.DIM,
    'event': colorama.Fore.BLUE + colorama.Style.BRIGHT
}

# all ANSI colors, except black, white and cyan
KV_COLORS = (
    colorama.Fore.RED, colorama.Fore.GREEN, colorama.Fore.YELLOW,
    colorama.Fore.BLUE, colorama.Fore.MAGENTA
)


def _color(key, colors):
    return COLORS.get(key, next(colors))


class ColorKeyValueRenderer(structlog.processors.KeyValueRenderer):
    'Renderer to output key values with colors'

    def __init__(self, force_colors=False, **kwargs):
        super().__init__(self, **kwargs)

        if force_colors:
            colorama.deinit()
            colorama.init(strip=False)
        else:
            colorama.init()

    def __call__(self, _, __, event_dict):
        colors_iterator = itertools.cycle(reversed(KV_COLORS))
        buffer = StringIO()

        for key, value in self._ordered_items(event_dict):
            if value is not None:
                if key == 'level':
                    buffer.write(
                        LEVEL_COLORS[value] + key + '=' + str(value) +
                        colorama.Style.RESET_ALL + ' '
                    )
                else:
                    buffer.write(
                        _color(key, colors_iterator) + key + '=' +
                        self._repr(value) + colorama.Style.RESET_ALL + ' '
                    )

        return buffer.getvalue()