[Django]-Django Setup Default Logging

As you said in your answer, Chris, one option to define a default logger is to use the empty string as its key.

However, I think the intended way is to define a special logger under the root key of the logging configuration dictionary. I found this in the Python documentation:

root – this will be the configuration for the root logger. Processing of the configuration will be as for any logger, except that the propagate setting will not be applicable.

Here’s the configuration from your answer changed to use the root key:

LOGGING = {
    'version': 1,
    'disable_existing_loggers': True,
    'formatters': {
        'standard': {
            'format': '%(asctime)s [%(levelname)s] %(name)s: %(message)s'
        },
    },
    'handlers': {
        'default': {
            'level':'DEBUG',
            'class':'logging.handlers.RotatingFileHandler',
            'filename': 'logs/mylog.log',
            'maxBytes': 1024*1024*5, # 5 MB
            'backupCount': 5,
            'formatter':'standard',
        },  
        'request_handler': {
            'level':'DEBUG',
            'class':'logging.handlers.RotatingFileHandler',
            'filename': 'logs/django_request.log',
            'maxBytes': 1024*1024*5, # 5 MB
            'backupCount': 5,
            'formatter':'standard',
        },
    },
    'root': {
        'handlers': ['default'],
        'level': 'DEBUG'
    },
    'loggers': {
        'django.request': {
            'handlers': ['request_handler'],
            'level': 'DEBUG',
            'propagate': False
        },
    }
}

To be fair, I can’t see any difference in behaviour between the two configurations. It appears that defining a logger with an empty string key will modify the root logger, because logging.getLogger('') will return the root logger.

The only reason I prefer 'root' over '' is that it is explicit about modifying the root logger. In case you were curious, 'root' overrides '' if you define both, just because the root entry is processed last.

import logging
logger = logging.getLogger(__name__)

after add:

logging.basicConfig(
    level = logging.DEBUG,
    format = '%(name)s %(levelname)s %(message)s',
)

we may change format to:

format = '"%(levelname)s:%(name)s:%(message)s"  ',

or

format = '%(name)s %(asctime)s %(levelname)s %(message)s',

I made a quick sample to check what configuration is used when both root key and the empty '' logger are referenced in config dict.

import logging.config

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'fmt1': {
            'format': '[FMT1] %(asctime)-15s %(message)s',
        },
        'fmt2': {
            'format': '[FMT2] %(asctime)-15s %(message)s',
        }
    },
    'handlers': {
        'console1': {
            'level': 'INFO',
            'class': 'logging.StreamHandler',
            'formatter': 'fmt1',
        },
        'console2': {
            'level': 'INFO',
            'class': 'logging.StreamHandler',
            'formatter': 'fmt2',
        },
    },
    # First config for root logger: console1 -> fmt1
    'root': {
        'handlers': ['console1'],
        'level': 'DEBUG',
        'propagate': True,
    },
    'loggers': {
        # Second config for root logger: console2 -> fmt2
        '': {
            'handlers': ['console2'],
            'level': 'DEBUG',
            'propagate': True,
        },
    },
}

logging.config.dictConfig(LOGGING)

l1 = logging.getLogger()
l2 = logging.getLogger('')
root = logging.root

l1.info("l1")
l2.info("l2")
root.info("root logger")

Prints the following result:

[FMT1] 2018-12-18 17:24:47,691 l1
[FMT1] 2018-12-18 17:24:47,691 l2
[FMT1] 2018-12-18 17:24:47,691 root logger

indicating that configuration under root key has the highest priority. If the block is removed, the result is:

[FMT2] 2018-12-18 17:25:43,757 l1
[FMT2] 2018-12-18 17:25:43,757 l2
[FMT2] 2018-12-18 17:25:43,757 root logger

In both case, I was able to debug and determine that all three loggers (l1, l2 and root) referenced the same logger instance, the root logger.

Hope that will help others who, like me, were confused by the 2 different ways to configure the root logger.