Document that LOGGING_CONFIG callback is not called when LOGGING dict is not set.

[Craig de Stigter]

the docs say:

LOGGING_CONFIG¶

Default: 'logging.config.dictConfig'

A path to a callable that will be used to configure logging in the Django project. Points at an instance of Python’s dictConfig configuration method by default.

If you set LOGGING_CONFIG to None, the logging configuration process will be skipped.

​https://docs.djangoproject.com/en/4.1/ref/settings/#logging-config

It turns out that in fact, you need to set LOGGING to some non-falsey value for the LOGGING_CONFIG callback to even be called at all. This isn't obvious - part of the reason for having a callback is if your logging is more dynamic than a dict-based config allows.

So now all our apps need some variation of this to work around this bug:

LOGGING = {"note": "this MUST be a non-falsey value for logging to work"}

I think this dependency on LOGGING should be clearly stated in the documentation for LOGGING_CONFIG, or just fixed (by always calling the LOGGING_CONFIG function even if LOGGING is falsey)

[Mariusz Felisiak]

Thanks for this report. I imagine it might be reasonable to call a custom callback without any configuration.

This limitation was added in a014ddfef2f606471f25c756d97b3b50fcbd9e91. Claude, does it work for you?

[Mariusz Felisiak]

Unfortunately, the default dictConfig crashes with empty LOGGING:

  File "/usr/lib/python3.8/logging/config.py", line 496, in configure
    raise ValueError("dictionary doesn't specify a version")
ValueError: dictionary doesn't specify a version

I imagine it might be reasonable to call a custom callback without any configuration.

It's rather niche, and proposed change is backward incompatible, so documenting this restriction seems like a reasonable consensus.

[Kinza-Raza]

I'd like to take this up.

[Kinza-Raza]

​https://github.com/django/django/pull/15978

[Carlton Gibson <carlton@…>]

In 5f5401b1:

Fixed #33920 -- Doc'd dependency of LOGGING_CONFIG callback on non-empty LOGGING.

[Carlton Gibson <carlton.gibson@…>]

In dafdceda:

[4.1.x] Fixed #33920 -- Doc'd dependency of LOGGING_CONFIG callback on non-empty LOGGING.

Backport of 5f5401b1149dca4a487eec6b1008124eacc7d29f from main