The doc is not right w.r.t. LOGGING overwriting.

[Vlada Macek]

The ​https://github.com/django/django/blob/master/docs/topics/logging.txt says

If the disable_existing_loggers key in the :setting:LOGGING dictConfig is set to True (which is the default) the default configuration is completely overridden.

That is not right and it is pretty painful to trace down that the django.request and django.security, although disabled, don't propagate to the root logger even when disable_existing_loggers in my LOGGING is True. One would expect the disabling would allow the logger to propagate again.

Many people apparently already ran into this.

There are Stack Overflow questions and blog posts about this topic. Best of them I found is here: ​http://www.caktusgroup.com/blog/2015/01/27/Django-Logging-Configuration-logging_config-default-settings-logger/

It suggests the working way to put to settings to really erase the default logging. I think it should definitely be stated in the doc.

LOGGING_CONFIG = None
LOGGING = {...}  # whatever you want

import logging.config
logging.config.dictConfig(LOGGING)

The logging system is complex by itself, something it is not a pleasure to work with for many. The reset path eliminating the confusion would be most welcome.

[Tim Graham]

I'll be happy to review any patch you could draft. See also #23394 and #23784.

[Vlada Macek]

Thank you. Sending a draft.

(Sorry, if the markup is wrong. ReST can compete with the logging module in opacity...)

[Vlada Macek]

There is a neat module logging_tree by Brandon Rhodes on PyPi that can be of tremendous help during understanding of the actual logger tree.

I don't know whether it could be considered to merge the module to Django, but what if I send a patch mentionting this module in the logging.txt doc?

[Tim Graham]

I lightly edited your patch and ​created a pull request so others can offer their thoughts. I also ​posted to django-developers to see if we can improve the state of logging in Django more generally.

[Paul Hallett]

Looks good and makes sense.

[Tim Graham <timograham@…>]

In c633667d:

Fixed #24361 -- Clarified docs on reconfiguring logging.

Thanks Tuttle for the report and draft patch, and Carl Meyer for
help and review.

[Tim Graham <timograham@…>]

In 0dc986d1:

[1.8.x] Fixed #24361 -- Clarified docs on reconfiguring logging.

Thanks Tuttle for the report and draft patch, and Carl Meyer for
help and review.

Backport of c633667da3605208ea5fc137f5322c599f48da69 from master

[Tim Graham <timograham@…>]

In 0121fb81:

[1.7.x] Fixed #24361 -- Clarified docs on reconfiguring logging.

Thanks Tuttle for the report and draft patch, and Carl Meyer for
help and review.

Backport of c633667da3605208ea5fc137f5322c599f48da69 from master

[Tim Graham <timograham@…>]

In 4a06a90:

Refs #24361 -- Corrected documented level of the 'django' logger.

The logger doesn't define an explicit level, therefore it defaults
to WARNING.

[Tim Graham <timograham@…>]

In 8f42934f:

[1.7.x] Refs #24361 -- Corrected documented level of the 'django' logger.

The logger doesn't define an explicit level, therefore it defaults
to WARNING.

Backport of 4a06a904dcd27388ec9a3cfb2bc8a8421bb44816 from stable/1.8.x