Logging is fun. We all want to be lumberjacks. My muscle-memory wants to put print statements everywhere, but it’s better to use log.debug instead. print statements make mod_wsgi sad, and they’re not much use in production. Plus, django-debug-toolbar can hijack the logger and show all the log statements generated during the last request. When DEBUG = True, all logs will be printed to the development console where you started the server. In production, we’re piping everything into syslog.
The root logger is set up from log_settings.py in the base of zamboni’s tree. It sets up sensible defaults, but you can twiddle with these settings:
This setting is required, and defaults to loggging.DEBUG, which will let just about anything pass through. To reconfigure, import logging in your settings file and pick a different level:
import logging
LOG_LEVEL = logging.WARN
See PEP 391 and log_settings.py for formatting help. Each section of LOGGING will get merged into the corresponding section of log_settings.py. Handlers and log levels are set up automatically based on LOG_LEVEL and DEBUG unless you set them here. Messages will not propagate through a logger unless propagate: True is set.
LOGGING = {
'loggers': {
'caching': {'handlers': ['null']},
},
}
If you want to add more to this in settings_local.py, do something like this:
LOGGING['loggers'].update({
'z.paypal': {
'level': logging.DEBUG,
},
'z.sphinx': {
'handlers': ['null'],
},
})
The logging package uses global objects to make the same logging configuration available to all code loaded in the interpreter. Loggers are created in a pseudo-namespace structure, so app-level loggers can inherit settings from a root logger. zamboni’s root namespace is just "z", in the interest of brevity. In the caching package, we create a logger that inherits the configuration by naming it "z.caching":
import commonware.log
log = commonware.log.getLogger('z.caching')
log.debug("I'm in the caching package.")
Logs can be nested as much as you want. Maintaining log namespaces is useful because we can turn up the logging output for a particular section of zamboni without becoming overwhelmed with logging from all other parts.
commonware.log.getLogger should be used inside the request cycle. It returns a LoggingAdapter that inserts the current user’s IP address into the log message.
Complete logging docs: http://docs.python.org/library/logging.html