How can I color Python logging output?

I already knew about the color escapes, I used them in my bash prompt a while ago. Thanks anyway. What I wanted was to integrate it with the logging module, which I eventually did after a couple of tries and errors. Here is what I end up with:

BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = range(8)

#The background is set with 40 plus the number of the color, and the foreground with 30

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

def formatter_message(message, use_color = True):
    if use_color:
        message = message.replace("$RESET", RESET_SEQ).replace("$BOLD", BOLD_SEQ)
    else:
        message = message.replace("$RESET", "").replace("$BOLD", "")
    return message

COLORS = {
    'WARNING': YELLOW,
    'INFO': WHITE,
    'DEBUG': BLUE,
    'CRITICAL': YELLOW,
    'ERROR': RED
}

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):
        levelname = record.levelname
        if self.use_color and levelname in COLORS:
            levelname_color = COLOR_SEQ % (30 + COLORS[levelname]) + levelname + RESET_SEQ
            record.levelname = levelname_color
        return logging.Formatter.format(self, record)

And to use it, create your own Logger:

# Custom logger class with multiple destinations
class ColoredLogger(logging.Logger):
    FORMAT = "[$BOLD%(name)-20s$RESET][%(levelname)-18s]  %(message)s ($BOLD%(filename)s$RESET:%(lineno)d)"
    COLOR_FORMAT = formatter_message(FORMAT, True)
    def __init__(self, name):
        logging.Logger.__init__(self, name, logging.DEBUG)                

        color_formatter = ColoredFormatter(self.COLOR_FORMAT)

        console = logging.StreamHandler()
        console.setFormatter(color_formatter)

        self.addHandler(console)
        return


logging.setLoggerClass(ColoredLogger)

Just in case anyone else needs it.

Be careful if you're using more than one logger or handler: ColoredFormatter is changing the record object, which is passed further to other handlers or propagated to other loggers. If you have configured file loggers etc. you probably don't want to have the colors in the log files. To avoid that, it's probably best to simply create a copy of record with copy.copy() before manipulating the levelname attribute, or to reset the levelname to the previous value, before returning the formatted string (credit to Michael in the comments).

---

Python 3 solution, no additional packages required

Define a class

import logging

class CustomFormatter(logging.Formatter):

    grey = "\x1b[38;20m"
    yellow = "\x1b[33;20m"
    red = "\x1b[31;20m"
    bold_red = "\x1b[31;1m"
    reset = "\x1b[0m"
    format = "%(asctime)s - %(name)s - %(levelname)s - %(message)s (%(filename)s:%(lineno)d)"

    FORMATS = {
        logging.DEBUG: grey + format + reset,
        logging.INFO: grey + format + reset,
        logging.WARNING: yellow + format + reset,
        logging.ERROR: red + format + reset,
        logging.CRITICAL: bold_red + format + reset
    }

    def format(self, record):
        log_fmt = self.FORMATS.get(record.levelno)
        formatter = logging.Formatter(log_fmt)
        return formatter.format(record)

Instantiate logger

# create logger with 'spam_application'
logger = logging.getLogger("My_app")
logger.setLevel(logging.DEBUG)

# create console handler with a higher log level
ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)

ch.setFormatter(CustomFormatter())

logger.addHandler(ch)

And use!

logger.debug("debug message")
logger.info("info message")
logger.warning("warning message")
logger.error("error message")
logger.critical("critical message")

https://i.stack.imgur.com/klCcc.png

https://i.stack.imgur.com/iZU5S.png

For windows

This solution works on Mac OS, IDE terminals. Looks like the Windows command prompt doesn't have colors at all by default. Here are instructions on how to enable them, which I haven't try https://www.howtogeek.com/322432/how-to-customize-your-command-prompts-color-scheme-with-microsofts-colortool/

---

Years ago I wrote a colored stream handler for my own use. Then I came across this page and found a collection of code snippets that people are copy/pasting :-(. My stream handler currently only works on UNIX (Linux, Mac OS X) but the advantage is that it's available on PyPI (and GitHub) and it's dead simple to use. It also has a Vim syntax mode :-). In the future I might extend it to work on Windows.

To install the package:

$ pip install coloredlogs

To confirm that it works:

$ coloredlogs --demo

To get started with your own code:

$ python
> import coloredlogs, logging
> coloredlogs.install()
> logging.info("It works!")
2014-07-30 21:21:26 peter-macbook root[7471] INFO It works!

The default log format shown in the above example contains the date, time, hostname, the name of the logger, the PID, the log level and the log message. This is what it looks like in practice:

https://i.stack.imgur.com/AgqpA.png

NOTE: When using Git Bash w/ MinTTY

Git Bash on windows has some documented quirks: Winpty and Git Bash

Which for ANSI escape codes and for ncurses style character rewriting and animations, you need to prefix commands with winpty.

$ winpty coloredlogs --demo
$ winpty python your_colored_logs_script.py

---

Update: Because this is an itch that I've been meaning to scratch for so long, I went ahead and wrote a library for lazy people like me who just want simple ways to do things: zenlog

Colorlog is excellent for this. It's available on PyPI (and thus installable through pip install colorlog) and is actively maintained.

Here's a quick copy-and-pasteable snippet to set up logging and print decent-looking log messages:

import logging
LOG_LEVEL = logging.DEBUG
LOGFORMAT = "  %(log_color)s%(levelname)-8s%(reset)s | %(log_color)s%(message)s%(reset)s"
from colorlog import ColoredFormatter
logging.root.setLevel(LOG_LEVEL)
formatter = ColoredFormatter(LOGFORMAT)
stream = logging.StreamHandler()
stream.setLevel(LOG_LEVEL)
stream.setFormatter(formatter)
log = logging.getLogger('pythonConfig')
log.setLevel(LOG_LEVEL)
log.addHandler(stream)

log.debug("A quirky message only developers care about")
log.info("Curious users might want to know this")
log.warn("Something is wrong and any user should be informed")
log.error("Serious stuff, this is red for a reason")
log.critical("OH NO everything is on fire")

Output:

https://github.com/ManufacturaInd/python-zenlog/raw/master/colorlogs.png

---

Quick and dirty solution for predefined log levels and without defining a new class.

logging.addLevelName( logging.WARNING, "\033[1;31m%s\033[1;0m" % logging.getLevelName(logging.WARNING))
logging.addLevelName( logging.ERROR, "\033[1;41m%s\033[1;0m" % logging.getLevelName(logging.ERROR))

---

Here is a solution that should work on any platform. If it doesn't just tell me and I will update it.

How it works: on platform supporting ANSI escapes is using them (non-Windows) and on Windows it does use API calls to change the console colors.

The script does hack the logging.StreamHandler.emit method from standard library adding a wrapper to it.

TestColorer.py

# Usage: add Colorer.py near you script and import it.
import logging
import Colorer

logging.warn("a warning")
logging.error("some error")
logging.info("some info")

Colorer.py

#!/usr/bin/env python
# encoding: utf-8
import logging
# now we patch Python code to add color support to logging.StreamHandler
def add_coloring_to_emit_windows(fn):
        # add methods we need to the class
    def _out_handle(self):
        import ctypes
        return ctypes.windll.kernel32.GetStdHandle(self.STD_OUTPUT_HANDLE)
    out_handle = property(_out_handle)

    def _set_color(self, code):
        import ctypes
        # Constants from the Windows API
        self.STD_OUTPUT_HANDLE = -11
        hdl = ctypes.windll.kernel32.GetStdHandle(self.STD_OUTPUT_HANDLE)
        ctypes.windll.kernel32.SetConsoleTextAttribute(hdl, code)

    setattr(logging.StreamHandler, '_set_color', _set_color)

    def new(*args):
        FOREGROUND_BLUE      = 0x0001 # text color contains blue.
        FOREGROUND_GREEN     = 0x0002 # text color contains green.
        FOREGROUND_RED       = 0x0004 # text color contains red.
        FOREGROUND_INTENSITY = 0x0008 # text color is intensified.
        FOREGROUND_WHITE     = FOREGROUND_BLUE|FOREGROUND_GREEN |FOREGROUND_RED
       # winbase.h
        STD_INPUT_HANDLE = -10
        STD_OUTPUT_HANDLE = -11
        STD_ERROR_HANDLE = -12

        # wincon.h
        FOREGROUND_BLACK     = 0x0000
        FOREGROUND_BLUE      = 0x0001
        FOREGROUND_GREEN     = 0x0002
        FOREGROUND_CYAN      = 0x0003
        FOREGROUND_RED       = 0x0004
        FOREGROUND_MAGENTA   = 0x0005
        FOREGROUND_YELLOW    = 0x0006
        FOREGROUND_GREY      = 0x0007
        FOREGROUND_INTENSITY = 0x0008 # foreground color is intensified.

        BACKGROUND_BLACK     = 0x0000
        BACKGROUND_BLUE      = 0x0010
        BACKGROUND_GREEN     = 0x0020
        BACKGROUND_CYAN      = 0x0030
        BACKGROUND_RED       = 0x0040
        BACKGROUND_MAGENTA   = 0x0050
        BACKGROUND_YELLOW    = 0x0060
        BACKGROUND_GREY      = 0x0070
        BACKGROUND_INTENSITY = 0x0080 # background color is intensified.     

        levelno = args[1].levelno
        if(levelno>=50):
            color = BACKGROUND_YELLOW | FOREGROUND_RED | FOREGROUND_INTENSITY | BACKGROUND_INTENSITY 
        elif(levelno>=40):
            color = FOREGROUND_RED | FOREGROUND_INTENSITY
        elif(levelno>=30):
            color = FOREGROUND_YELLOW | FOREGROUND_INTENSITY
        elif(levelno>=20):
            color = FOREGROUND_GREEN
        elif(levelno>=10):
            color = FOREGROUND_MAGENTA
        else:
            color =  FOREGROUND_WHITE
        args[0]._set_color(color)

        ret = fn(*args)
        args[0]._set_color( FOREGROUND_WHITE )
        #print "after"
        return ret
    return new

def add_coloring_to_emit_ansi(fn):
    # add methods we need to the class
    def new(*args):
        levelno = args[1].levelno
        if(levelno>=50):
            color = '\x1b[31m' # red
        elif(levelno>=40):
            color = '\x1b[31m' # red
        elif(levelno>=30):
            color = '\x1b[33m' # yellow
        elif(levelno>=20):
            color = '\x1b[32m' # green 
        elif(levelno>=10):
            color = '\x1b[35m' # pink
        else:
            color = '\x1b[0m' # normal
        args[1].msg = color + args[1].msg +  '\x1b[0m'  # normal
        #print "after"
        return fn(*args)
    return new

import platform
if platform.system()=='Windows':
    # Windows does not support ANSI escapes and we are using API calls to set the console color
    logging.StreamHandler.emit = add_coloring_to_emit_windows(logging.StreamHandler.emit)
else:
    # all non-Windows platforms are supporting ANSI escapes so we use them
    logging.StreamHandler.emit = add_coloring_to_emit_ansi(logging.StreamHandler.emit)
    #log = logging.getLogger()
    #log.addFilter(log_filter())
    #//hdlr = logging.StreamHandler()
    #//hdlr.setFormatter(formatter())

---

Well, I guess I might as well add my variation of the colored logger.

This is nothing fancy, but it is very simple to use and does not change the record object, thereby avoids logging the ANSI escape sequences to a log file if a file handler is used. It does not effect the log message formatting.

If you are already using the logging module's Formatter, all you have to do to get colored level names is to replace your counsel handlers Formatter with the ColoredFormatter. If you are logging an entire app you only need to do this for the top level logger.

colored_log.py

#!/usr/bin/env python

from copy import copy
from logging import Formatter

MAPPING = {
    'DEBUG'   : 37, # white
    'INFO'    : 36, # cyan
    'WARNING' : 33, # yellow
    'ERROR'   : 31, # red
    'CRITICAL': 41, # white on red bg
}

PREFIX = '\033['
SUFFIX = '\033[0m'

class ColoredFormatter(Formatter):

    def __init__(self, patern):
        Formatter.__init__(self, patern)

    def format(self, record):
        colored_record = copy(record)
        levelname = colored_record.levelname
        seq = MAPPING.get(levelname, 37) # default white
        colored_levelname = ('{0}{1}m{2}{3}') \
            .format(PREFIX, seq, levelname, SUFFIX)
        colored_record.levelname = colored_levelname
        return Formatter.format(self, colored_record)

Example usage

app.py

#!/usr/bin/env python

import logging
from colored_log import ColoredFormatter

# Create top level logger
log = logging.getLogger("main")

# Add console handler using our custom ColoredFormatter
ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)
cf = ColoredFormatter("[%(name)s][%(levelname)s]  %(message)s (%(filename)s:%(lineno)d)")
ch.setFormatter(cf)
log.addHandler(ch)

# Add file handler
fh = logging.FileHandler('app.log')
fh.setLevel(logging.DEBUG)
ff = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
fh.setFormatter(ff)
log.addHandler(fh)

# Set log level
log.setLevel(logging.DEBUG)

# Log some stuff
log.debug("app has started")
log.info("Logging to 'app.log' in the script dir")
log.warning("This is my last warning, take heed")
log.error("This is an error")
log.critical("He's dead, Jim")

# Import a sub-module 
import sub_module

sub_module.py

#!/usr/bin/env python

import logging
log = logging.getLogger('main.sub_module')

log.debug("Hello from the sub module")

Results

Terminal output

https://i.stack.imgur.com/OsmlG.png

app.log content

2017-09-29 00:32:23,434 - main - DEBUG - app has started
2017-09-29 00:32:23,434 - main - INFO - Logging to 'app.log' in the script dir
2017-09-29 00:32:23,435 - main - WARNING - This is my last warning, take heed
2017-09-29 00:32:23,435 - main - ERROR - This is an error
2017-09-29 00:32:23,435 - main - CRITICAL - He's dead, Jim
2017-09-29 00:32:23,435 - main.sub_module - DEBUG - Hello from the sub module

Of course you can get as fancy as you want with formatting the terminal and log file outputs. Only the log level will be colorized.

I hope somebody finds this useful and it is not just too much more of the same. :)

The Python example files can be downloaded from this GitHub Gist: https://gist.github.com/KurtJacobson/48e750701acec40c7161b5a2f79e6bfd

---

You can import the colorlog module and use its ColoredFormatter for colorizing log messages.

Example

Boilerplate for main module:

import logging
import os
import sys
try:
    import colorlog
except ImportError:
    pass

def setup_logging():
    root = logging.getLogger()
    root.setLevel(logging.DEBUG)
    format      = '%(asctime)s - %(levelname)-8s - %(message)s'
    date_format = '%Y-%m-%d %H:%M:%S'
    if 'colorlog' in sys.modules and os.isatty(2):
        cformat = '%(log_color)s' + format
        f = colorlog.ColoredFormatter(cformat, date_format,
              log_colors = { 'DEBUG'   : 'reset',       'INFO' : 'reset',
                             'WARNING' : 'bold_yellow', 'ERROR': 'bold_red',
                             'CRITICAL': 'bold_red' })
    else:
        f = logging.Formatter(format, date_format)
    ch = logging.StreamHandler()
    ch.setFormatter(f)
    root.addHandler(ch)

setup_logging()
log = logging.getLogger(__name__)

The code only enables colors in log messages, if the colorlog module is installed and if the output actually goes to a terminal. This avoids escape sequences being written to a file when the log output is redirected.

Also, a custom color scheme is setup that is better suited for terminals with dark background.

Some example logging calls:

log.debug   ('Hello Debug')
log.info    ('Hello Info')
log.warn    ('Hello Warn')
log.error   ('Hello Error')
log.critical('Hello Critical')

Output:

https://i.stack.imgur.com/lWWpI.png

---

I updated the example from airmind supporting tags for foreground and background. Just use the color variables $BLACK - $WHITE in your log formatter string. To set the background just use $BG-BLACK - $BG-WHITE.

import logging

BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = range(8)

COLORS = {
    'WARNING'  : YELLOW,
    'INFO'     : WHITE,
    'DEBUG'    : BLUE,
    'CRITICAL' : YELLOW,
    'ERROR'    : RED,
    'RED'      : RED,
    'GREEN'    : GREEN,
    'YELLOW'   : YELLOW,
    'BLUE'     : BLUE,
    'MAGENTA'  : MAGENTA,
    'CYAN'     : CYAN,
    'WHITE'    : WHITE,
}

RESET_SEQ = "\033[0m"
COLOR_SEQ = "\033[1;%dm"
BOLD_SEQ  = "\033[1m"

class ColorFormatter(logging.Formatter):

    def __init__(self, *args, **kwargs):
        # can't do super(...) here because Formatter is an old school class
        logging.Formatter.__init__(self, *args, **kwargs)

    def format(self, record):
        levelname = record.levelname
        color     = COLOR_SEQ % (30 + COLORS[levelname])
        message   = logging.Formatter.format(self, record)
        message   = message.replace("$RESET", RESET_SEQ)\
                           .replace("$BOLD",  BOLD_SEQ)\
                           .replace("$COLOR", color)
        for k,v in COLORS.items():
            message = message.replace("$" + k,    COLOR_SEQ % (v+30))\
                             .replace("$BG" + k,  COLOR_SEQ % (v+40))\
                             .replace("$BG-" + k, COLOR_SEQ % (v+40))
        return message + RESET_SEQ

logging.ColorFormatter = ColorFormatter

So now you can simple do the following in your config file:

[formatter_colorFormatter]
class=logging.ColorFormatter
format= $COLOR%(levelname)s $RESET %(asctime)s $BOLD$COLOR%(name)s$RESET %(message)s

---

I modified the original example provided by Sorin and subclassed StreamHandler to a ColorizedConsoleHandler.

The downside of their solution is that it modifies the message, and because that is modifying the actual logmessage any other handlers will get the modified message as well.

This resulted in logfiles with colorcodes in them in our case because we use multiple loggers.

The class below only works on platforms that support ANSI, but it should be trivial to add the Windows colorcodes to it.

import copy
import logging


class ColoredConsoleHandler(logging.StreamHandler):
    def emit(self, record):
        # Need to make a actual copy of the record
        # to prevent altering the message for other loggers
        myrecord = copy.copy(record)
        levelno = myrecord.levelno
        if(levelno >= 50):  # CRITICAL / FATAL
            color = '\x1b[31m'  # red
        elif(levelno >= 40):  # ERROR
            color = '\x1b[31m'  # red
        elif(levelno >= 30):  # WARNING
            color = '\x1b[33m'  # yellow
        elif(levelno >= 20):  # INFO
            color = '\x1b[32m'  # green
        elif(levelno >= 10):  # DEBUG
            color = '\x1b[35m'  # pink
        else:  # NOTSET and anything else
            color = '\x1b[0m'  # normal
        myrecord.msg = color + str(myrecord.msg) + '\x1b[0m'  # normal
        logging.StreamHandler.emit(self, myrecord)

---

Look at the following solution. The stream handler should be the thing doing the colouring, then you have the option of colouring words rather than just the whole line (with the Formatter).

http://plumberjack.blogspot.com/2010/12/colorizing-logging-output-in-terminals.html

---

Now there is a released PyPi module for customizable colored logging output:

https://pypi.python.org/pypi/rainbow_logging_handler/

and

https://github.com/laysakura/rainbow_logging_handler

Supports Windows

Supports Django

Customizable colors

As this is distributed as a Python egg, it is very easy to install for any Python application.

---

What about highlighting also log message arguments with alternating colors, in addition to coloring by level? I recently wrote simple code for that. Another advantage is that log call is made with Python 3 brace-style formatting. ("{}").

See latest code and examples here: https://github.com/davidohana/colargulog

Sample Logging code:

root_logger = logging.getLogger()
console_handler = logging.StreamHandler(stream=sys.stdout)
console_format = "%(asctime)s - %(levelname)-8s - %(name)-25s - %(message)s"
colored_formatter = ColorizedArgsFormatter(console_format)
console_handler.setFormatter(colored_formatter)
root_logger.addHandler(console_handler)

logger = logging.getLogger(__name__)
logger.info("Hello World")
logger.info("Request from {} handled in {:.3f} ms", socket.gethostname(), 11)
logger.info("Request from {} handled in {:.3f} ms", "127.0.0.1", 33.1)
logger.info("My favorite drinks are {}, {}, {}, {}", "milk", "wine", "tea", "beer")
logger.debug("this is a {} message", logging.getLevelName(logging.DEBUG))
logger.info("this is a {} message", logging.getLevelName(logging.INFO))
logger.warning("this is a {} message", logging.getLevelName(logging.WARNING))
logger.error("this is a {} message", logging.getLevelName(logging.ERROR))
logger.critical("this is a {} message", logging.getLevelName(logging.CRITICAL))
logger.info("Does old-style formatting also work? %s it is, but no colors (yet)", True)

Output:

https://i.stack.imgur.com/0Or6e.png

Implementation:

"""
colargulog - Python3 Logging with Colored Arguments and new string formatting style

Written by david.ohana@ibm.com
License: Apache-2.0
"""

import logging
import logging.handlers
import re


class ColorCodes:
    grey = "\x1b[38;21m"
    green = "\x1b[1;32m"
    yellow = "\x1b[33;21m"
    red = "\x1b[31;21m"
    bold_red = "\x1b[31;1m"
    blue = "\x1b[1;34m"
    light_blue = "\x1b[1;36m"
    purple = "\x1b[1;35m"
    reset = "\x1b[0m"


class ColorizedArgsFormatter(logging.Formatter):
    arg_colors = [ColorCodes.purple, ColorCodes.light_blue]
    level_fields = ["levelname", "levelno"]
    level_to_color = {
        logging.DEBUG: ColorCodes.grey,
        logging.INFO: ColorCodes.green,
        logging.WARNING: ColorCodes.yellow,
        logging.ERROR: ColorCodes.red,
        logging.CRITICAL: ColorCodes.bold_red,
    }

    def __init__(self, fmt: str):
        super().__init__()
        self.level_to_formatter = {}

        def add_color_format(level: int):
            color = ColorizedArgsFormatter.level_to_color[level]
            _format = fmt
            for fld in ColorizedArgsFormatter.level_fields:
                search = "(%\(" + fld + "\).*?s)"
                _format = re.sub(search, f"{color}\\1{ColorCodes.reset}", _format)
            formatter = logging.Formatter(_format)
            self.level_to_formatter[level] = formatter

        add_color_format(logging.DEBUG)
        add_color_format(logging.INFO)
        add_color_format(logging.WARNING)
        add_color_format(logging.ERROR)
        add_color_format(logging.CRITICAL)

    @staticmethod
    def rewrite_record(record: logging.LogRecord):
        if not BraceFormatStyleFormatter.is_brace_format_style(record):
            return

        msg = record.msg
        msg = msg.replace("{", "_{{")
        msg = msg.replace("}", "_}}")
        placeholder_count = 0
        # add ANSI escape code for next alternating color before each formatting parameter
        # and reset color after it.
        while True:
            if "_{{" not in msg:
                break
            color_index = placeholder_count % len(ColorizedArgsFormatter.arg_colors)
            color = ColorizedArgsFormatter.arg_colors[color_index]
            msg = msg.replace("_{{", color + "{", 1)
            msg = msg.replace("_}}", "}" + ColorCodes.reset, 1)
            placeholder_count += 1

        record.msg = msg.format(*record.args)
        record.args = []

    def format(self, record):
        orig_msg = record.msg
        orig_args = record.args
        formatter = self.level_to_formatter.get(record.levelno)
        self.rewrite_record(record)
        formatted = formatter.format(record)

        # restore log record to original state for other handlers
        record.msg = orig_msg
        record.args = orig_args
        return formatted


class BraceFormatStyleFormatter(logging.Formatter):
    def __init__(self, fmt: str):
        super().__init__()
        self.formatter = logging.Formatter(fmt)

    @staticmethod
    def is_brace_format_style(record: logging.LogRecord):
        if len(record.args) == 0:
            return False

        msg = record.msg
        if '%' in msg:
            return False

        count_of_start_param = msg.count("{")
        count_of_end_param = msg.count("}")

        if count_of_start_param != count_of_end_param:
            return False

        if count_of_start_param != len(record.args):
            return False

        return True

    @staticmethod
    def rewrite_record(record: logging.LogRecord):
        if not BraceFormatStyleFormatter.is_brace_format_style(record):
            return

        record.msg = record.msg.format(*record.args)
        record.args = []

    def format(self, record):
        orig_msg = record.msg
        orig_args = record.args
        self.rewrite_record(record)
        formatted = self.formatter.format(record)

        # restore log record to original state for other handlers
        record.msg = orig_msg
        record.args = orig_args
        return formatted

---

Install the colorlog package, you can use colors in your log messages immediately:

Obtain a logger instance, exactly as you would normally do.

Set the logging level. You can also use the constants like DEBUG and INFO from the logging module directly.

Set the message formatter to be the ColoredFormatter provided by the colorlog library.

import colorlog

logger = colorlog.getLogger()
logger.setLevel(colorlog.colorlog.logging.DEBUG)

handler = colorlog.StreamHandler()
handler.setFormatter(colorlog.ColoredFormatter())
logger.addHandler(handler)

logger.debug("Debug message")
logger.info("Information message")
logger.warning("Warning message")
logger.error("Error message")
logger.critical("Critical message")

https://i.stack.imgur.com/sXE9G.png

UPDATE: extra info

Just update ColoredFormatter:

handler.setFormatter(colorlog.ColoredFormatter('%(log_color)s [%(asctime)s] %(levelname)s [%(filename)s.%(funcName)s:%(lineno)d] %(message)s', datefmt='%a, %d %b %Y %H:%M:%S'))

https://i.stack.imgur.com/UMeCl.png

Package:

pip install colorlog

output:

Collecting colorlog
  Downloading colorlog-4.6.2-py2.py3-none-any.whl (10.0 kB)
Installing collected packages: colorlog
Successfully installed colorlog-4.6.2

---

A simple but very flexible tool for coloring ANY terminal text is 'colout'.

pip install colout
myprocess | colout REGEX_WITH_GROUPS color1,color2...

Where any text in the output of 'myprocess' which matches group 1 of the regex will be colored with color1, group 2 with color2, etc.

For example:

tail -f /var/log/mylogfile | colout '^(\w+ \d+ [\d:]+)|(\w+\.py:\d+ .+\(\)): (.+)$' white,black,cyan bold,bold,normal

i.e. the first regex group (parens) matches the initial date in the logfile, the second group matches a python filename, line number and function name, and the third group matches the log message that comes after that. I also use a parallel sequence of 'bold/normals' as well as the sequence of colors. This looks like:

https://i.stack.imgur.com/99ztB.png

Note that lines or parts of lines which don't match any of my regex are still echoed, so this isn't like 'grep --color' - nothing is filtered out of the output.

Obviously this is flexible enough that you can use it with any process, not just tailing logfiles. I usually just whip up a new regex on the fly any time I want to colorize something. For this reason, I prefer colout to any custom logfile-coloring tool, because I only need to learn one tool, regardless of what I'm coloring: logging, test output, syntax highlighting snippets of code in the terminal, etc.

It also avoids actually dumping ANSI codes in the logfile itself, which IMHO is a bad idea, because it will break things like grepping for patterns in the logfile unless you always remember to match the ANSI codes in your grep regex.

---

There are tons of responses. But none is talking about decorators. So here's mine.

Because it is a lot more simple.

There's no need to import anything, nor to write any subclass:

#!/usr/bin/env python
# -*- coding: utf-8 -*-


import logging


NO_COLOR = "\33[m"
RED, GREEN, ORANGE, BLUE, PURPLE, LBLUE, GREY = \
    map("\33[%dm".__mod__, range(31, 38))

logging.basicConfig(format="%(message)s", level=logging.DEBUG)
logger = logging.getLogger(__name__)

# the decorator to apply on the logger methods info, warn, ...
def add_color(logger_method, color):
  def wrapper(message, *args, **kwargs):
    return logger_method(
      # the coloring is applied here.
      color+message+NO_COLOR,
      *args, **kwargs
    )
  return wrapper

for level, color in zip((
  "info", "warn", "error", "debug"), (
  GREEN, ORANGE, RED, BLUE
)):
  setattr(logger, level, add_color(getattr(logger, level), color))

# this is displayed in red.
logger.error("Launching %s." % __file__)

This set the errors in red, debug messages in blue, and so on. Like asked in the question.

We could even adapt the wrapper to take a color argument to dynamicaly set the message's color using logger.debug("message", color=GREY)

EDIT: So here's the adapted decorator to set colors at runtime:

def add_color(logger_method, _color):
  def wrapper(message, *args, **kwargs):
    color = kwargs.pop("color", _color)
    if isinstance(color, int):
      color = "\33[%dm" % color
    return logger_method(
      # the coloring is applied here.
      color+message+NO_COLOR,
      *args, **kwargs
    )
  return wrapper

# blah blah, apply the decorator...

# this is displayed in red.
logger.error("Launching %s." % __file__)
# this is displayed in blue
logger.error("Launching %s." % __file__, color=34)
# and this, in grey
logger.error("Launching %s." % __file__, color=GREY)

---

Use the rich library

Rich supplies a logging handler which will format and colorize text written by Python's logging module.

It is easy to use and customizable + works in cmd.exe, Windows Terminal, ConEmu and Jupyter Notebook! (I tried many packages I tell ya, only rich's color works in the notebook.).

Rich also comes with many other fancy features.

Installation

pip install rich

Minimal example:

import logging
from rich.logging import RichHandler

FORMAT = "%(message)s"
logging.basicConfig(
    level="NOTSET", format=FORMAT, datefmt="[%X]", handlers=[RichHandler()]
)  # set level=20 or logging.INFO to turn of debug
logger = logging.getLogger("rich")

logger.debug("debug...")
logger.info("info...")
logger.warning("warning...")
logger.error("error...")
logger.fatal("fatal...")

https://i.stack.imgur.com/rn3ZO.png

---

Another minor remix of airmind's approach that keeps everything in one class:

class ColorFormatter(logging.Formatter):
  FORMAT = ("[$BOLD%(name)-20s$RESET][%(levelname)-18s]  "
            "%(message)s "
            "($BOLD%(filename)s$RESET:%(lineno)d)")

  BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = range(8)

  RESET_SEQ = "\033[0m"
  COLOR_SEQ = "\033[1;%dm"
  BOLD_SEQ = "\033[1m"

  COLORS = {
    'WARNING': YELLOW,
    'INFO': WHITE,
    'DEBUG': BLUE,
    'CRITICAL': YELLOW,
    'ERROR': RED
  }

  def formatter_msg(self, msg, use_color = True):
    if use_color:
      msg = msg.replace("$RESET", self.RESET_SEQ).replace("$BOLD", self.BOLD_SEQ)
    else:
      msg = msg.replace("$RESET", "").replace("$BOLD", "")
    return msg

  def __init__(self, use_color=True):
    msg = self.formatter_msg(self.FORMAT, use_color)
    logging.Formatter.__init__(self, msg)
    self.use_color = use_color

  def format(self, record):
    levelname = record.levelname
    if self.use_color and levelname in self.COLORS:
      fore_color = 30 + self.COLORS[levelname]
      levelname_color = self.COLOR_SEQ % fore_color + levelname + self.RESET_SEQ
      record.levelname = levelname_color
    return logging.Formatter.format(self, record)

To use attach the formatter to a handler, something like:

handler.setFormatter(ColorFormatter())
logger.addHandler(handler)

---

coloredlogs

Instalation

pip install coloredlogs

Usage

Minimal usage:

import logging
import coloredlogs

coloredlogs.install()  # install a handler on the root logger

logging.debug('message with level debug')
logging.info('message with level info')
logging.warning('message with level warning')
logging.error('message with level error')
logging.critical('message with level critical')

https://i.stack.imgur.com/A1axw.png

Start from message level debug:

import logging
import coloredlogs

coloredlogs.install(level='DEBUG')  # install a handler on the root logger with level debug

logging.debug('message with level debug')
logging.info('message with level info')
logging.warning('message with level warning')
logging.error('message with level error')
logging.critical('message with level critical')

https://i.stack.imgur.com/S3AAi.png

Hide messages from libraries:

import logging
import coloredlogs

logger = logging.getLogger(__name__)  # get a specific logger object
coloredlogs.install(level='DEBUG')  # install a handler on the root logger with level debug
coloredlogs.install(level='DEBUG', logger=logger)  # pass a specific logger object

logging.debug('message with level debug')
logging.info('message with level info')
logging.warning('message with level warning')
logging.error('message with level error')
logging.critical('message with level critical')

https://i.stack.imgur.com/S3AAi.png

Format log messages:

import logging
import coloredlogs

logger = logging.getLogger(__name__)  # get a specific logger object
coloredlogs.install(level='DEBUG')  # install a handler on the root logger with level debug
coloredlogs.install(level='DEBUG', logger=logger)  # pass a specific logger object
coloredlogs.install(
    level='DEBUG', logger=logger,
    fmt='%(asctime)s.%(msecs)03d %(filename)s:%(lineno)d %(levelname)s %(message)s'
)

logging.debug('message with level debug')
logging.info('message with level info')
logging.warning('message with level warning')
logging.error('message with level error')
logging.critical('message with level critical')

https://i.stack.imgur.com/0aBWR.png

Available format attributes:

%(asctime)s - Time as human-readable string, when logging call was issued

%(created)f - Time as float when logging call was issued

%(filename)s - File name

%(funcName)s - Name of function containing the logging call

%(hostname)s - System hostname

%(levelname)s - Text logging level

%(levelno)s - Integer logging level

%(lineno)d - Line number where the logging call was issued

%(message)s - Message passed to logging call (same as %(msg)s)

%(module)s - File name without extension where the logging call was issued

%(msecs)d - Millisecond part of the time when logging call was issued

%(msg)s - Message passed to logging call (same as %(message)s)

%(name)s - Logger name

%(pathname)s - Full pathname to file containing the logging call

%(process)d - Process ID

%(processName)s - Process name

%(programname)s - System programname

%(relativeCreated)d - Time as integer in milliseconds when logging call was issued, relative to the time when logging module was loaded

%(thread)d - Thread ID

%(threadName)s - Thread name

%(username)s - System username

Sources:

Coloredlogs package

Logging library

---

import logging
import sys

colors = {'pink': '\033[95m', 'blue': '\033[94m', 'green': '\033[92m', 'yellow': '\033[93m', 'red': '\033[91m',
      'ENDC': '\033[0m', 'bold': '\033[1m', 'underline': '\033[4m'}

logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)


def str_color(color, data):
    return colors[color] + str(data) + colors['ENDC']

params = {'param1': id1, 'param2': id2}

logging.info('\nParams:' + str_color("blue", str(params)))`

---

Solution using standard Python3 logging library

I am pretty excited to share this flexible solution for log coloring. I think it is an improvement to this solution by @SergeyPleshakov. I leveraged the log record's extra kwargs to set a log prefix and suffix. Then we just default the prefix and suffix to start and end with terminal color codes that correspond with the log level.

bonus feature ✨ 🍰 ✨

The extra prefix and suffix can be overridden by the log call to be whatever. You want your debug log to be prefixed with a 🐛, why not. You want a one of the info logs to be Green instead of the default, go for it!

Define the terminal Color and ColorLogFormatter classes

import logging


class Color:
    """A class for terminal color codes."""

    BOLD = "\033[1m"
    BLUE = "\033[94m"
    WHITE = "\033[97m"
    GREEN = "\033[92m"
    YELLOW = "\033[93m"
    RED = "\033[91m"
    BOLD_WHITE = BOLD + WHITE
    BOLD_BLUE = BOLD + BLUE
    BOLD_GREEN = BOLD + GREEN
    BOLD_YELLOW = BOLD + YELLOW
    BOLD_RED = BOLD + RED
    END = "\033[0m"


class ColorLogFormatter(logging.Formatter):
    """A class for formatting colored logs."""

    FORMAT = "%(prefix)s%(msg)s%(suffix)s"

    LOG_LEVEL_COLOR = {
        "DEBUG": {'prefix': '', 'suffix': ''},
        "INFO": {'prefix': '', 'suffix': ''},
        "WARNING": {'prefix': Color.BOLD_YELLOW, 'suffix': Color.END},
        "ERROR": {'prefix': Color.BOLD_RED, 'suffix': Color.END},
        "CRITICAL": {'prefix': Color.BOLD_RED, 'suffix': Color.END},
    }

    def format(self, record):
        """Format log records with a default prefix and suffix to terminal color codes that corresponds to the log level name."""
        if not hasattr(record, 'prefix'):
            record.prefix = self.LOG_LEVEL_COLOR.get(record.levelname.upper()).get('prefix')
        
        if not hasattr(record, 'suffix'):
            record.suffix = self.LOG_LEVEL_COLOR.get(record.levelname.upper()).get('suffix')

        formatter = logging.Formatter(self.FORMAT)
        return formatter.format(record)

Instantiate logger

logger = logging.getLogger('bobcat')
logger.setLevel('DEBUG')

stream_handler = logging.StreamHandler()
stream_handler.setFormatter(ColorLogFormatter())
logger.addHandler(stream_handler)

And use!

    logger.debug("This is debug", extra={'prefix': '🐛 '})
    logger.info("This is info")
    logger.info("This is a green info", extra={'prefix': Color.GREEN, 'suffix': Color.END})
    logger.warning("This is warning")
    logger.error("This is error")
    logger.critical("This is critical")

and Voilà!

https://i.stack.imgur.com/ZQJpg.png

---

Here's my solution:

class ColouredFormatter(logging.Formatter):
    RESET = '\x1B[0m'
    RED = '\x1B[31m'
    YELLOW = '\x1B[33m'
    BRGREEN = '\x1B[01;32m'  # grey in solarized for terminals

    def format(self, record, colour=False):
        message = super().format(record)

        if not colour:
            return message

        level_no = record.levelno
        if level_no >= logging.CRITICAL:
            colour = self.RED
        elif level_no >= logging.ERROR:
            colour = self.RED
        elif level_no >= logging.WARNING:
            colour = self.YELLOW
        elif level_no >= logging.INFO:
            colour = self.RESET
        elif level_no >= logging.DEBUG:
            colour = self.BRGREEN
        else:
            colour = self.RESET

        message = colour + message + self.RESET

        return message


class ColouredHandler(logging.StreamHandler):
    def __init__(self, stream=sys.stdout):
        super().__init__(stream)

    def format(self, record, colour=False):
        if not isinstance(self.formatter, ColouredFormatter):
            self.formatter = ColouredFormatter()

        return self.formatter.format(record, colour)

    def emit(self, record):
        stream = self.stream
        try:
            msg = self.format(record, stream.isatty())
            stream.write(msg)
            stream.write(self.terminator)
            self.flush()
        except Exception:
            self.handleError(record)


h = ColouredHandler()
h.formatter = ColouredFormatter('{asctime} {levelname:8} {message}', '%Y-%m-%d %H:%M:%S', '{')
logging.basicConfig(level=logging.DEBUG, handlers=[h])

---

FriendlyLog is another alternative. It works with Python 2 & 3 under Linux, Windows and MacOS.

---

This is another Python3 variant of airmind's example. I wanted some specific features I didn't see in the other examples

use colors for the terminal but do not write non-printable characters in the file handlers (I defined 2 formatters for this)

ability to override the color for a specific log message

configure the logger from a file (yaml in this case)

Notes: I used colorama but you could modify this so it is not required. Also for my testing I was just running python file so my class is in module __main__ You would have to change (): __main__.ColoredFormatter to whatever your module is.

pip install colorama pyyaml

logging.yaml

---
version: 1
disable_existing_loggers: False
formatters:
  simple:
    format: "%(threadName)s - %(name)s - %(levelname)s - %(message)s"
  color:
    format: "%(threadName)s - %(name)s - %(levelname)s - %(message)s"
    (): __main__.ColoredFormatter
    use_color: true

handlers:
  console:
    class: logging.StreamHandler
    level: DEBUG
    formatter: color
    stream: ext://sys.stdout

  info_file_handler:
    class: logging.handlers.RotatingFileHandler
    level: INFO
    formatter: simple
    filename: app.log
    maxBytes: 20971520 
    backupCount: 20
    encoding: utf8

  error_file_handler:
    class: logging.handlers.RotatingFileHandler
    level: ERROR
    formatter: simple
    filename: errors.log
    maxBytes: 10485760 
    backupCount: 20
    encoding: utf8

root:
  level: DEBUG
  handlers: [console, info_file_handler, error_file_handler]

main.py

import logging
import logging.config
import os
from logging import Logger

import colorama
import yaml
from colorama import Back, Fore, Style

COLORS = {
    "WARNING": Fore.YELLOW,
    "INFO": Fore.CYAN,
    "DEBUG": Fore.BLUE,
    "CRITICAL": Fore.YELLOW,
    "ERROR": Fore.RED,
}


class ColoredFormatter(logging.Formatter):
    def __init__(self, *, format, use_color):
        logging.Formatter.__init__(self, fmt=format)
        self.use_color = use_color

    def format(self, record):
        msg = super().format(record)
        if self.use_color:
            levelname = record.levelname
            if hasattr(record, "color"):
                return f"{record.color}{msg}{Style.RESET_ALL}"
            if levelname in COLORS:
                return f"{COLORS[levelname]}{msg}{Style.RESET_ALL}"
        return msg


with open("logging.yaml", "rt") as f:
    config = yaml.safe_load(f.read())
    logging.config.dictConfig(config)

logger: Logger = logging.getLogger(__name__)
logger.info("Test INFO", extra={"color": Back.RED})
logger.info("Test INFO", extra={"color": f"{Style.BRIGHT}{Back.RED}"})
logger.info("Test INFO")
logger.debug("Test DEBUG")
logger.warning("Test WARN")

output:

https://i.stack.imgur.com/AsvRt.png

---

Emoji

You can use colors for text as others mentioned in their answers to have colorful text with a background or foreground color.

But you can use emojis instead! for example, you can use ⚠️ for warning messages and 🛑 for error messages.

Or simply use these notebooks as a color:

print("📕: error message")
print("📙: warning message")
print("📗: ok status message")
print("📘: action message")
print("📓: canceled status message")
print("📔: Or anything you like and want to recognize immediately by color")

🎁 Bonus:

This method also helps you to quickly scan and find logs directly in the source code.

How to open emoji picker?

mac os: control + command + space

windows: win + .

linux: control + . or control + ;

---

The bit I had trouble with was setting up the formatter properly:

class ColouredFormatter(logging.Formatter):    
    def __init__(self, msg):
        logging.Formatter.__init__(self, msg)
        self._init_colour = _get_colour()

    def close(self):
        # restore the colour information to what it was
        _set_colour(self._init_colour)

    def format(self, record):        
        # Add your own colourer based on the other examples
        _set_colour( LOG_LEVEL_COLOUR[record.levelno] )
        return logging.Formatter.format(self, record)         

def init():
    # Set up the formatter. Needs to be first thing done.
    rootLogger = logging.getLogger()
    hdlr = logging.StreamHandler()
    fmt = ColouredFormatter('%(message)s')
    hdlr.setFormatter(fmt)
    rootLogger.addHandler(hdlr)

And then to use:

import coloured_log
import logging

coloured_log.init()
logging.info("info")    
logging.debug("debug")    

coloured_log.close()    # restore colours

---

While the other solutions seem fine they have some issues. Some do colour the whole lines which some times is not wanted and some omit any configuration you might have all together. The solution below doesn't affect anything but the message itself.

Code

class ColoredFormatter(logging.Formatter):
    def format(self, record):
        if record.levelno == logging.WARNING:
            record.msg = '\033[93m%s\033[0m' % record.msg
        elif record.levelno == logging.ERROR:
            record.msg = '\033[91m%s\033[0m' % record.msg
        return logging.Formatter.format(self, record)

Example

logger = logging.getLogger('mylogger')
handler = logging.StreamHandler()

log_format = '[%(asctime)s]:%(levelname)-7s:%(message)s'
time_format = '%H:%M:%S'
formatter = ColoredFormatter(log_format, datefmt=time_format)
handler.setFormatter(formatter)
logger.addHandler(handler)

logger.warn('this should be yellow')
logger.error('this should be red')

Output

[17:01:36]:WARNING:this should be yellow
[17:01:37]:ERROR  :this should be red

As you see, everything else still gets outputted and remain in their initial color. If you want to change anything else than the message you can simply pass the color codes to log_format in the example.

---

I have two submissions to add, one of which colorizes just the message (ColoredFormatter), and one of which colorizes the entire line (ColorizingStreamHandler). These also include more ANSI color codes than previous solutions.

Some content has been sourced (with modification) from: The post above, and http://plumberjack.blogspot.com/2010/12/colorizing-logging-output-in-terminals.html.

Colorizes the message only:

class ColoredFormatter(logging.Formatter):
    """Special custom formatter for colorizing log messages!"""

    BLACK = '\033[0;30m'
    RED = '\033[0;31m'
    GREEN = '\033[0;32m'
    BROWN = '\033[0;33m'
    BLUE = '\033[0;34m'
    PURPLE = '\033[0;35m'
    CYAN = '\033[0;36m'
    GREY = '\033[0;37m'

    DARK_GREY = '\033[1;30m'
    LIGHT_RED = '\033[1;31m'
    LIGHT_GREEN = '\033[1;32m'
    YELLOW = '\033[1;33m'
    LIGHT_BLUE = '\033[1;34m'
    LIGHT_PURPLE = '\033[1;35m'
    LIGHT_CYAN = '\033[1;36m'
    WHITE = '\033[1;37m'

    RESET = "\033[0m"

    def __init__(self, *args, **kwargs):
        self._colors = {logging.DEBUG: self.DARK_GREY,
                        logging.INFO: self.RESET,
                        logging.WARNING: self.BROWN,
                        logging.ERROR: self.RED,
                        logging.CRITICAL: self.LIGHT_RED}
        super(ColoredFormatter, self).__init__(*args, **kwargs)

    def format(self, record):
        """Applies the color formats"""
        record.msg = self._colors[record.levelno] + record.msg + self.RESET
        return logging.Formatter.format(self, record)

    def setLevelColor(self, logging_level, escaped_ansi_code):
        self._colors[logging_level] = escaped_ansi_code

Colorizes the whole line:

class ColorizingStreamHandler(logging.StreamHandler):

    BLACK = '\033[0;30m'
    RED = '\033[0;31m'
    GREEN = '\033[0;32m'
    BROWN = '\033[0;33m'
    BLUE = '\033[0;34m'
    PURPLE = '\033[0;35m'
    CYAN = '\033[0;36m'
    GREY = '\033[0;37m'

    DARK_GREY = '\033[1;30m'
    LIGHT_RED = '\033[1;31m'
    LIGHT_GREEN = '\033[1;32m'
    YELLOW = '\033[1;33m'
    LIGHT_BLUE = '\033[1;34m'
    LIGHT_PURPLE = '\033[1;35m'
    LIGHT_CYAN = '\033[1;36m'
    WHITE = '\033[1;37m'

    RESET = "\033[0m"

    def __init__(self, *args, **kwargs):
        self._colors = {logging.DEBUG: self.DARK_GREY,
                        logging.INFO: self.RESET,
                        logging.WARNING: self.BROWN,
                        logging.ERROR: self.RED,
                        logging.CRITICAL: self.LIGHT_RED}
        super(ColorizingStreamHandler, self).__init__(*args, **kwargs)

    @property
    def is_tty(self):
        isatty = getattr(self.stream, 'isatty', None)
        return isatty and isatty()

    def emit(self, record):
        try:
            message = self.format(record)
            stream = self.stream
            if not self.is_tty:
                stream.write(message)
            else:
                message = self._colors[record.levelno] + message + self.RESET
                stream.write(message)
            stream.write(getattr(self, 'terminator', '\n'))
            self.flush()
        except (KeyboardInterrupt, SystemExit):
            raise
        except:
            self.handleError(record)

    def setLevelColor(self, logging_level, escaped_ansi_code):
        self._colors[logging_level] = escaped_ansi_code

---

Just answered the same on similar question: Python | change text color in shell

The idea is to use the clint library. Which has support for MAC, Linux and Windows shells (CLI).

---

import logging

logging.basicConfig(filename="f.log" filemode='w', level=logging.INFO,
                    format = "%(logger_name)s %(color)s  %(message)s %(endColor)s")


class Logger(object):
    __GREEN = "\033[92m"
    __RED = '\033[91m'
    __ENDC = '\033[0m'

    def __init__(self, name):
        self.logger = logging.getLogger(name)
        self.extra={'logger_name': name, 'endColor': self.__ENDC, 'color': self.__GREEN}


    def info(self, msg):
        self.extra['color'] = self.__GREEN
        self.logger.info(msg, extra=self.extra)

    def error(self, msg):
        self.extra['color'] = self.__RED
        self.logger.error(msg, extra=self.extra)

Usage

Logger("File Name").info("This shows green text")

---