Using a variable while calling logger.setLevel

Question

Does anyone know if there is a way to use a variable in the setlevel() function of Python's Logging module?

At the moment I am using this:

Log = logging.getLogger('myLogger')
Log.setLevel(logging.DEBUG)

But I'd like to have this:

Log = logging.getLogger('myLogger')
levels = {'CRITICAL' : logging.critical,
    'ERROR' : logging.error,
    'WARNING' : logging.warning,
    'INFO' : logging.info,
    'DEBUG' : logging.debug
}
level = levels['INFO']
Log.setLevel(level)

But it doesn't seem to work - it just doesn't log anything.

I'm doing this so that I can set the logging level for a whole bunch of scripts from a variable in a single config file.

Answer 1

I find that leveraging an optional environmental variable is very convenient and flexible:

class Foo():
    def __init__(self):
        self.logger = logging.getLogger(__name__)
        level = logging.getLevelName(os.environ.get('LOG_LEVEL', 'ERROR'))
        logging.basicConfig(level=level)

    def bar(self):
        self.logger.debug('Log something')

Answer 2

You should also be able to do this:

Log = logging.getLogger('myLogger')
level = logging.getLevelName('INFO')
Log.setLevel(level)

The logging.getLevelName(lvl) function works both ways. I use it, it works (you should check your python implementation though).

This saves you the trouble to maintain your own dictionary, and reduces the possibility of typo errors.

Answer 3

logging.setLevel() takes an int or a str.

So the following works just fine (at least in Python 3.7):

logger = logging.getLogger(__name__)
logger.setLevel("DEBUG")

Answer 4

What about using getattr on logging module?

import logging
str_level = 'DEBUG'
level = getattr(logging, str_level)
logger = logging.getLogger("my_logger")
logger.setLevel(level)
print(logger.getEffectiveLevel())

Answer 5

I had problems with python 3 and got this working for me: https://docs.python.org/3/howto/logging.html

# myapp.py
import logging
import mylib

def main():
    logging.basicConfig(filename='myapp.log', level=logging.INFO)
    logging.info('Started')
    mylib.do_something()
    logging.info('Finished')

if __name__ == '__main__':
    main()