Python logging setLevel() not taking effect

Question

I have a python program that utilizes multiprocessing to increase efficiency, and a function that creates a logger for each process. The logger function looks like this:

import logging
import os

def create_logger(app_name):
    """Create a logging interface"""
    # create a logger
    if logging in os.environ:
        logging_string = os.environ["logging"]
        if logging_string == "DEBUG":
            logging_level = loggin.DEBUG
        else if logging_string == "INFO":
            logging_level = logging.INFO
        else if logging_string == "WARNING":
            logging_level = logging.WARNING
        else if logging_string == "ERROR":
            logging_level = logging.ERROR
        else if logging_string == "CRITICAL":
            logging_level = logging.CRITICAL
    else:
        logging_level = logging.INFO

    logger = logging.getLogger(app_name)
    logger.setLevel(logging_level)

    # Console handler for error output
    console_handler = logging.StreamHandler()
    console_handler.setLevel(logging_level)

    # Formatter to make everything look nice
    formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
    console_handler.setFormatter(formatter)

    # Add the handlers to the logger
    logger.addHandler(console_handler)

    return logger

And my processing functions look like this:

import custom_logging

def do_capture(data_dict_access):
    """Process data"""

    # Custom logging
    LOGGER = custom_logging.create_logger("processor")

    LOGGER.debug("Doing stuff...")

However, no matter what the logging environment variable is set to, I still receive debug log messages in the console. Why is my logging level not taking effect, surely the calls to setLevel() should stop the debug messages from being logged?

Answer 1

Here is an easy way to create a logger object:

import logging
import os

def create_logger(app_name):
    """Create a logging interface"""
    logging_level = os.getenv('logging', logging.INFO)
    logging.basicConfig(
        level=logging_level,
        format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')
    logger = logging.getLogger(app_name)
    return logger

Discussion

• There is no need to convert from "DEBUG" to logging.DEBUG, the logging module understands these strings.
• Use basicConfig to ease the pain of setting up a logger. You don't need to create handler, set format, set level, ... This should work for most cases.

Update

I found out why your code does not work, besides the else if. Consider your line:

if logging in os.environ:

On this line loggging without quote refers to the logging library package. What you want is:

if 'logging' in os.environ: