python logging: How to replace the output file of a FileHandler?

Question

This is for Python 2.7 ....

I have a Django project, and I use logging.config.dictConfig(CONFIG) to get the logging that I want when running the Django app as a server. I have my own module in mycore.logging, and it creates a logger object at import-time. This is all great.

However, Django has independent 'management commands' and I want to log each management command to its own separate file. The logfile name would be the name of the management command + ".log".

I've searched and googled and not found any examples of this. Is it really so unusual? Or have I just not found the prior art?

I think I know how to remove the existing FileHandler, instantiate a new one with my desired output file, and add it as a handler on the logger object.

But it seems like a clunky thing to do. Any advice will be welcome.

import logging
import logging.config
from logutils.colorize import ColorizingStreamHandler
from django.conf import settings

class ColorHandler(ColorizingStreamHandler):
    def __init__(self, *args, **kwargs):
        super(ColorHandler, self).__init__(*args, **kwargs)
        self.level_map = {
                # Provide your custom coloring information here
                logging.DEBUG: (None, 'blue', False),
                logging.INFO: (None, 'green', False),
                logging.WARNING: (None, 'yellow', False),
                logging.ERROR: (None, 'red', False),
                logging.CRITICAL: ('red', 'white', True),

        }

try:
    CONSOLE_LOG_LEVEL = settings.CONSOLE_LOG_LEVEL
except AttributeError as ae:
    CONSOLE_LOG_LEVEL =  logging.INFO
try:
    FILE_LOG_LEVEL = settings.FILE_LOG_LEVEL
except AttributeError as ae:
    FILE_LOG_LEVEL =  logging.DEBUG

CONFIG = {
    'version':1,
    'disable_existing_loggers': True,
    'handlers':{
        'console': {
            '()':ColorHandler,
            'level': CONSOLE_LOG_LEVEL,
            'formatter': 'simplest',
            'stream': 'ext://sys.stdout',
        },
        'file': {
            'class': 'logging.handlers.RotatingFileHandler',
            'level': FILE_LOG_LEVEL,
            'formatter': 'simplest',
            'filename': './log-oxfam.txt',
            'mode': 'a',
            'maxBytes': 10485760,
            'backupCount': 5,
        },
    },
    'formatters': {
        'simplest': {
            'format': '%(levelname)-8s %(message)s',
        },
        'time_level_message': {
            'format': '%(asctime)s %(levelname)-8s %(message)s',
        },
        'detailed': {
            'format': '%(asctime)s %(module)s line:%(lineno)-4d %(levelname)-8s %(message)s',
        },
    },
    'loggers': {
        'myDjangoApp': {
            'level':'DEBUG',
            'handlers':['console', 'file'],
            ###'handlers':['console'],
        },
    },
}

logging.config.dictConfig(CONFIG)
logger = logging.getLogger("myDjangoApp")

user1600649 · Accepted Answer · 2017-06-30 17:26:17Z

1

I would base the solution around logging.handlers.QueueHandler. It's pretty much the only one that isn't tied to a storage facility. Your listeners can decide at runtime where to put things.

answered Jun 30, 2017 at 17:26

user1600649

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4 Comments

Bill Torcaso Over a year ago

My bad. I need a solution in python 2.7. I clarified the description to say so.

user1600649 Over a year ago

Don't see an easy solution there. You'd pretty much have to somehow teach a MemoryView to go threaded with the old threading library that doesn't have a Queue (luckily there is collections.deque, but still). I now remember why I migrated to 3.x though :)

Bill Torcaso Over a year ago

I think I haven't been clear about the thing that I want. Here is a summary: -- At import time, my utility code instantiates a log object. That does what I need. -- At __main__() time, in selected, independent commands, I want to replace (entirely) the FileHandler that exists within my logger object, with new FileHandler object with the same attributes as the original except that it writes to a different file.

Vinay Sajip Over a year ago

@BillTorcaso You can use the logutils project to provide QueueHandler functionality under Python 2.7 - pip install logutils.

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