Trouble propagating logging configuration

[Dieter Maurer]

Loris Bennett wrote at 2021-9-1 13:48 +0200:
> ...
>Yes, but to quote from https://docs.python.org/3.6/howto/logging.html#logging-basic-tutorial:
>
>  A good convention to use when naming loggers is to use a module-level
>  logger, in each module which uses logging, named as follows:
>
>    logger = logging.getLogger(__name__)
>
>  This means that logger names track the package/module hierarchy, and
>  it’s intuitively obvious where events are logged just from the logger
>  name.
>
>so in this case the source layout is relevant, isn't it?

Relevant in this case is the package/module hierarchy.

Often the package/module hierarchy follows the source layout
**BUT** this is not necessarily the case.

In particular, the "start" module of a script is called `__main__`
indepently of its location.
Furthermore, so called "namespace packages" consist of
decentralized (i.e. located at different places in the file system)
subpackages.

Thus, in general, the connection between pachage/module hierarchy
and the source layout is loose.


>> Furthermore, the place of the configuration (and where in the
>> code it is activated) is completely irrelevant for the "inheritance".
>
>OK, so one issue is that I was getting confused by the *order* in which
>modules are being called.  If I have two modules, 'foo' and 'bar', in
>the same directory, configure the logging just in 'foo' and then call
>
>
>  foo.some_method()
>  bar.some_method()
>
>then both methods will be logged.   If I do
>
>  bar.some_method()
>  foo.some_method()
>
>then only the method in 'foo' will be logged.

Usually, log configuration is considered a (global) application
(not a (local) package/module) concern:
The components (modules) decide what to log at what level
and global configuration decides what to do with those messages.

Thus, typically, you configure the complete logging in
your main application module and then start to import modules
and call their functions.

> ...
>If I have
>
>  [loggers]
>  keys=root,main,log_test
>
>in my logging configuration and initialise  the logging in run.py  ...

This logging configuration is obviously not complete (thus, I cannot
check what happens in your case).
You may have made errors at other places in your configuration
which may explain your observations.

At your place, I would look at the `logging` source code
to find out where you can see (in an interactive Python session)
which loggers have been created by your configuration and
how they are configured. For the last part you use "vars(logger)".



--
Dieter