CODEWITHSUNDEEP
pythondebugginglogging
xetra11
xetra11

Reputation: 8885

Enabling debug logging in Python

Given this code I try to have log statements working but I am not able to. The documentation tells me that I do not have to set a level.

When a logger is created, the level is set to NOTSET (which causes all messages to be processed when the logger is the root logger, or delegation to the parent when the logger is a non-root logger).

But it did not work without. Therefore I tried to set it to debug. But still no luck.

"""
Experimental Port Fowarding
"""
import logging

def main(config):
    """ entry point"""

    log = logging.getLogger(__name__)
    log.setLevel(logging.DEBUG)

    log.debug("opening config file...")
    config_file = open(config, 'r')
    log.debug("config found!")

Upvotes: 0

Views: 8347

Answers (2)

GyRo
GyRo

Reputation: 2646

By default the logger writes to STDERR stream which usually prints to the console itself.
Basically you can change the log file path by setting:

logging.basicConfig(filename="YourFileName.log")
log = logging.getLogger(__name__)

Upvotes: 0

chthonicdaemon
chthonicdaemon

Reputation: 19830

The logger you are getting doesn't have any handlers. You can check this by doing print(log.handlers) and seeing the output is an empty list ([]).

The simplest way to use the logging library is something like this, where you call logging.basicConfig to set everything up, as shown in the logging module basic tutorial:

"""
Experimental Port Fowarding
"""
import logging

logging.basicConfig(level=logging.DEBUG)

def main(config):
    """ entry point"""

    logging.debug("opening config file...")
    config_file = open(config, 'r')
    logging.debug("config found!")

main('test.conf')

This works for me from outside and inside IPython.

If you want to avoid basicConfig for some reason you need to register a handler manually, like this:

import logging

def main(config):
    """ entry point"""

    log = logging.getLogger(__name__)
    log.setLevel(logging.DEBUG)
    # Minimal change: add StreamHandler to display to stdout
    log.addHandler(logging.StreamHandler())

    log.debug("opening config file...")
    config_file = open(config, 'r')
    log.debug("config found!")

Upvotes: 3

Related Questions