Question or problem about Python programming:
Some time ago, I saw a Mono application with colored output, presumably because of its log system (because all the messages were standardized).
Now, Python has the logging module, which lets you specify a lot of options to customize output. So, I’m imagining something similar would be possible with Python, but I can’t find out how to do this anywhere.
Is there any way to make the Python logging module output in color?
What I want (for instance) errors in red, debug messages in blue or yellow, and so on.
Of course this would probably require a compatible terminal (most modern terminals are); but I could fallback to the original logging output if color isn’t supported.
Any ideas how I can get colored output with the logging module?
How to solve the problem:
Solution 1:
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).
Solution 2:
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:
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
Solution 3:
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:
Solution 4:
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())
Solution 5:
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))
