Django logging on Heroku

Logging on Heroku from Django can be tricky at first, but it’s actually not that horrible to get set up.

This following logging definition (goes into your settings file) defined two formatters. The verbose one matches the logging format Heroku itself uses. It also defines two handlers, a null handler (shouldn’t need to be used) and a console handler – the console handler is what you want to use with Heroku. The reason for this is that logging on Heroku works by a simple stream logger, logging any output made to stdout/stderr. Lastly, I’ve defined one logger called testlogger – this part of the logging definition goes like normal for logging definitions.

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'verbose': {
            'format': ('%(asctime)s [%(process)d] [%(levelname)s] ' +
                       'pathname=%(pathname)s lineno=%(lineno)s ' +
                       'funcname=%(funcName)s %(message)s'),
            'datefmt': '%Y-%m-%d %H:%M:%S'
        },
        'simple': {
            'format': '%(levelname)s %(message)s'
        }
    },
    'handlers': {
        'null': {
            'level': 'DEBUG',
            'class': 'logging.NullHandler',
        },
        'console': {
            'level': 'DEBUG',
            'class': 'logging.StreamHandler',
            'formatter': 'verbose'
        }
    },
    'loggers': {
        'testlogger': {
            'handlers': ['console'],
            'level': 'INFO',
        }
    }
}

Next up, how to use this. In this simple case, you can do the following in any other file in your Django project, to write to this specific logger we defined (testlogger). Remember that by the logger definition in our settings file, any log message INFO or above will be output.

import logging
logger = logging.getLogger('testlogger')
logger.info('This is a simple log message')