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24 Nov 2021

211124-1731 python logging setup

(By MO at work)

Naming loggers after the package / files

Logger names can be used to cleanly output and separate them.

Assuming one has a package with multiple files/subfolders in it, it’s possible to give each one their own logger, like this:

In the main file of the package:

logger = logging.getLogger(__package__)

In all the other files:

logger = logging.getLogger(__name__)

That way paths ./package/my_module.py lead to loggers named like package.my_module that map the semantical and the directory structure.

Changing settings of the loggers

In a setup above, one can then easily change the settings of the loggers referring to them by their names.

Configuring logging: Logging HOWTO — Python 3.10.0 documentation

Changing loglevel is easy from code,

if args.debug:
		logger.setLevel(logging.DEBUG)

logging.config allows to change the config from ini-like config files. Two main ways: logging.config.fileConfig reads ini-like config files, logging.config.dictConfig 1 from dictionaries.

Sample .yaml that when converted to dict would change the loglevel of different loggers:

version: 1
                               
loggers:
	packageName.mymodule1:
		level: DEBUG
	packageName.mymodule2:
		level: DEBUG

These loggers can even include external ones!


  1. logging.config — Logging configuration — Python 3.10.0 documentation ↩︎

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