Python logging in multiple modules

Question

I want to write a logger which I can use in multiple modules. I must be able to enable and disable it from one place. And it must be reusable.

Following is the scenario. switch_module.py

class Brocade(object):
    def __init__(self, ip, username, password):
        ...

    def connect(self):
        ...
    def disconnect(self):
        ...
    def switch_show(self):
        ...

switch_module_library.py

import switch_module

class Keyword_Mapper(object):
    def __init__(self, keyword_to_execute):
        self._brocade_object = switch_module.Brocade(ip, username, password)
        ...
    def map_keyword_to_command(self)
        ...

application_gui.py

class GUI:
    # I can open a file containing keyword for brocade switch
    # in this GUI in a tab and tree widget(it uses PyQt which I don't know)
    # Each tab is a QThread and there could be multiple tabs

    # Each tab is accompanied by an execute button.
    # On pressing exeute it will read the string/keywords from the file
    # and create an object of keyword_Mapper class and call
    # map_key_word_to_command method, execute the command on brocade
    # switch and log the results. Current I am logging the result
    # only from the Keyword_Mapper class.

Problem I have is how to write a logger which could be enabled and disabled at will and it must log to one file as well as console from all three modules.

I tried writing global logger in int.py and then importing it in all three modules and had to give a common name so that they log to the same file, but then ran into trouble since there is multi-threading and later created logger to log to a file which has thread-id in its name so that I can have each log per thread.

What if I am required to log to different file rather than the same file?

I have gone through python logging documentation but am unable to get a clear picture about writing a proper logging system which could be reused.

I have gone through this link Is it better to use root logger or named logger in Python

but due to the GUI created by someone other than me using PyQt and multi-threading I am unable to get my head around logging here.

score 1 · Accepted Answer · answered Dec 23 '14 at 22:49

I my project I only use a root logger (I dont have the time to create named loggers, even if it would be nice). So if you don't want to use a named logger, here is a quick solution:

I created a function to set up logger quickly:

import logging

def initLogger(level=logging.DEBUG):
    if level == logging.DEBUG:
        # Display more stuff when in a debug mode
        logging.basicConfig(
            format='%(levelname)s-%(module)s:%(lineno)d-%(funcName)s: %(message)s',
            level=level)
    else:
        # Display less stuff for info mode
        logging.basicConfig(format='%(levelname)s: %(message)s', level=level)

I created a package for it so that I can import it anywhere.

Then, in my top level I have:

import LoggingTools
if __name__ == '__main__':
    # Configure logger
    LoggingTools.initLogger(logging.DEBUG)
    #LoggingTools.initLogger(logging.INFO)

Depending if I am debugging or not, I using the corresponding statement.

Then in each other files, I just use the logging:

import logging
class MyClass():
    def __init__(self):
        logging.debug("Debug message")
        logging.info("Info message")

Python logging in multiple modules

1 Answers1