Best practices for logging in setup.py

[mwtoews]

With dynamic aspects of setup.py it is useful to see messages on (e.g.) discovery of libraries to compile modules. What is the best practice to show these messages?

I've been looking at setuptools/tests/test_logging.py for inspiration, but it only tests the internal logging. Could this logger be extended for other purposes? The standard logging module (now used by setuptools) is an obvious way, but it's not clear how it should be used.

Attempt 1

This attempt only shows "BEFORE setup()" from log threshold WARNING and higher before setup() and then for "MESSAGE TWO" either DEBUG or higher with --verbose or INFO or higher without.

import logging
from setuptools import setup

log = logging.getLogger()

log.debug("BEFORE setup() DEBUG")
log.info("BEFORE setup() INFO")
log.warning("BEFORE setup() WARNING")

setup(name="test_logging", version="0.1")

log.debug("AFTER setup() DEBUG")
log.info("AFTER setup() INFO")
log.warning("AFTER setup() WARNING")

Here it is with --verbose:

$ python setup.py --verbose sdist
BEFORE setup() WARNING
... running sdist ...
AFTER setup() DEBUG
AFTER setup() INFO
AFTER setup() WARNING

Attempt 2

This uses non-public API and is a hack.

import logging
from setuptools import setup
from setuptools import logging as setuptools_logging

setuptools_logging.configure()
log = logging.getLogger()

log.debug("BEFORE setup() DEBUG")
log.info("BEFORE setup() INFO")
log.warning("BEFORE setup() WARNING")

setup(name="test_logging", version="0.2")

log.debug("AFTER setup() DEBUG")
log.info("AFTER setup() INFO")
log.warning("AFTER setup() WARNING")

and now without --verbose:

$ python setup.py sdist
BEFORE setup() DEBUG
BEFORE setup() INFO
BEFORE setup() WARNING
running sdist
...
AFTER setup() INFO
AFTER setup() WARNING

Analysis and expected behaviour

With both of the examples, the logger behaves as expected after setup(), as it has set the appropriate log level based on the presence (or absence) of a verbose flag. However, these messages are used to show messages gathering data before setup(). Neither of the above two attempts show messages for the appropriate logger level. Is there a better way?

And as a bonus question, why does the placement order of --verbose matter? E.g. python setup.py sdist --verbose ignores the verbose flag.

[webknjaz]

I haven't seen anybody caring about such logging, except for an occasional exception message being longer.

But FWIW abusing setup.py as a command wrapper (i.e. calling it directly) is highly discouraged and only the use via the PEP 517 interface is supported, any other misuses are deprecated.
https://blog.ganssle.io/articles/2021/10/setup-py-deprecated.html

[mwtoews]

Yes, I'm aware calling setup.py is deprecated, just providing simple demos. Similar outputs can be obtained via python -m build --sdist

[webknjaz]

Well, I haven't seen anything more involved than this https://github.com/pyca/cryptography/blob/d7d6b19/setup.py#L80-L91.