Python logging: colourising terminal output

ansistrm.py

#
# Copyright (C) 2010-2012 Vinay Sajip. All rights reserved. Licensed under the new BSD license.
#
import ctypes
import logging
import os

class ColorizingStreamHandler(logging.StreamHandler):
    # color names to indices
    color_map = {
        'black': 0,
        'red': 1,
        'green': 2,
        'yellow': 3,
        'blue': 4,
        'magenta': 5,
        'cyan': 6,
        'white': 7,
    }

    #levels to (background, foreground, bold/intense)
    if os.name == 'nt':
        level_map = {
            logging.DEBUG: (None, 'blue', True),
            logging.INFO: (None, 'white', False),
            logging.WARNING: (None, 'yellow', True),
            logging.ERROR: (None, 'red', True),
            logging.CRITICAL: ('red', 'white', True),
        }
    else:
        level_map = {
            logging.DEBUG: (None, 'blue', False),
            logging.INFO: (None, 'black', False),
            logging.WARNING: (None, 'yellow', False),
            logging.ERROR: (None, 'red', False),
            logging.CRITICAL: ('red', 'white', True),
        }
    csi = '\x1b['
    reset = '\x1b[0m'

    @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:
                self.output_colorized(message)
            stream.write(getattr(self, 'terminator', '\n'))
            self.flush()
        except (KeyboardInterrupt, SystemExit):
            raise
        except:
            self.handleError(record)

    if os.name != 'nt':
        def output_colorized(self, message):
            self.stream.write(message)
    else:
        import re
        ansi_esc = re.compile(r'\x1b\[((?:\d+)(?:;(?:\d+))*)m')

        nt_color_map = {
            0: 0x00,    # black
            1: 0x04,    # red
            2: 0x02,    # green
            3: 0x06,    # yellow
            4: 0x01,    # blue
            5: 0x05,    # magenta
            6: 0x03,    # cyan
            7: 0x07,    # white
        }

        def output_colorized(self, message):
            parts = self.ansi_esc.split(message)
            write = self.stream.write
            h = None
            fd = getattr(self.stream, 'fileno', None)
            if fd is not None:
                fd = fd()
                if fd in (1, 2): # stdout or stderr
                    h = ctypes.windll.kernel32.GetStdHandle(-10 - fd)
            while parts:
                text = parts.pop(0)
                if text:
                    write(text)
                if parts:
                    params = parts.pop(0)
                    if h is not None:
                        params = [int(p) for p in params.split(';')]
                        color = 0
                        for p in params:
                            if 40 <= p <= 47:
                                color |= self.nt_color_map[p - 40] << 4
                            elif 30 <= p <= 37:
                                color |= self.nt_color_map[p - 30]
                            elif p == 1:
                                color |= 0x08 # foreground intensity on
                            elif p == 0: # reset to default color
                                color = 0x07
                            else:
                                pass # error condition ignored
                        ctypes.windll.kernel32.SetConsoleTextAttribute(h, color)

    def colorize(self, message, record):
        if record.levelno in self.level_map:
            bg, fg, bold = self.level_map[record.levelno]
            params = []
            if bg in self.color_map:
                params.append(str(self.color_map[bg] + 40))
            if fg in self.color_map:
                params.append(str(self.color_map[fg] + 30))
            if bold:
                params.append('1')
            if params:
                message = ''.join((self.csi, ';'.join(params),
                                   'm', message, self.reset))
        return message

    def format(self, record):
        message = logging.StreamHandler.format(self, record)
        if self.is_tty:
            # Don't colorize any traceback
            parts = message.split('\n', 1)
            parts[0] = self.colorize(parts[0], record)
            message = '\n'.join(parts)
        return message

def main():
    root = logging.getLogger()
    root.setLevel(logging.DEBUG)
    root.addHandler(ColorizingStreamHandler())
    logging.debug('DEBUG')
    logging.info('INFO')
    logging.warning('WARNING')
    logging.error('ERROR')
    logging.critical('CRITICAL')

if __name__ == '__main__':
    main()

Gist updated to use non-capturing groups. Thanks to Marius Gedminas for the suggestion.

this also seems to only require ctypes fi you're using NT

@unux: Good point. Gist updated. Thanks.

With python 2.7, this didn't work for me on windows 64bit without "import ctypes" at the top :. Either way, thanks :D

I was looking for this! Thanks for sharing. I'm using your code in a github project I'm developing. Is it enough to keep the copyright notice at the top of the file? Module is here.

Hi Vítor, I've updated the Gist to clarify in the copyright notice that the licensing is new BSD. Please ensure you update your copy with the new notice. Regards, Vinay Sajip

…

----- Original Message -----

From: Vítor Brandão ***@***.*** To: Vinay Sajip ***@***.*** Cc: Sent: Saturday, 14 April 2012, 23:57 Subject: Re: gist gist: 758430 I was looking for this! Thanks for sharing. I'm using your code in a [github project](https://github.com/noiselabs/box-linux-sync) I'm developing. Is it enough to keep the copyright notice at the top of the file? Module is [here](https://github.com/noiselabs/box-linux-sync/blob/master/src/noiselabs/box/ansistrm.py). --- Reply to this email directly or view it on GitHub: https://gist.github.com/758430

Done. Thanks.

Providing an __init__() will facilitate the customization when using dictConfig()

    def __init__(self, level_map=None, *args, **kwargs):
        if level_map is not None:
            self.level_map = level_map
        logging.StreamHandler.__init__(self, *args, **kwargs)

According to the code, the logging.INFO level seems to be the terminal default, if you comment it or set all params to None you do not have to make a special case for nt:

--- ansistrm.py.orig    2012-10-24 15:52:45.051056546 +0200
+++ ansistrm.py 2012-10-24 15:57:06.599067746 +0200
@@ -19,25 +19,21 @@
     }

     #levels to (background, foreground, bold/intense)
-    if os.name == 'nt':
-        level_map = {
-            logging.DEBUG: (None, 'blue', True),
-            logging.INFO: (None, 'white', False),
-            logging.WARNING: (None, 'yellow', True),
-            logging.ERROR: (None, 'red', True),
-            logging.CRITICAL: ('red', 'white', True),
-        }
-    else:
-        level_map = {
-            logging.DEBUG: (None, 'blue', False),
-            logging.INFO: (None, 'black', False),
-            logging.WARNING: (None, 'yellow', False),
-            logging.ERROR: (None, 'red', False),
-            logging.CRITICAL: ('red', 'white', True),
-        }
+    level_map = {
+        logging.DEBUG: (None, 'blue', False),
+        logging.INFO: (None, None, False),
+        logging.WARNING: (None, 'yellow', False),
+        logging.ERROR: (None, 'red', False),
+        logging.CRITICAL: ('red', 'white', True),
+    }
     csi = '\x1b['
     reset = '\x1b[0m'

+    def __init__(self, level_map=None, *args, **kwargs):
+        if level_map is not None:
+            self.level_map = level_map
+        logging.StreamHandler.__init__(self, *args, **kwargs)
+
     @property
     def is_tty(self):
         isatty = getattr(self.stream, 'isatty', None)

Thanks for the gist, well done!
On my terminal (gnome 3.4.1.1) white you specified in the color_map is 'normal white' but not the one the terminal actually uses ('bright white'), so I had to change in the color_map to 'white':9 instead of original 7. Value 9 should mean the default text color.

After switching from win7 64bit to win8 64bit the following ctypes declaration was needed:

import ctypes
ctypes.windll.kernel32.SetConsoleTextAttribute.argtypes = [ctypes.c_ulong, ctypes.c_ushort]

for python3 support:

import sys
if os.name != 'nt':
    def output_colorized(self, message):
        if sys.version[0] == '2':
            self.stream.write(message)
        else:
            self.stream.write(message.decode())