PYTHON

setup logger python

# Logger setup in python
def get_logger(self) -> logging.RootLogger:
    """instance of logger module, will be used for logging operations"""
    
    # logger config
    logger = logging.getLogger(__name__)
    logger.setLevel(logging.DEBUG)

    # log format
    lg_format = "%(levelname)s|%(filename)s:%(lineno)d|%(asctime)s|%(message)s"
    log_format = logging.Formatter(lg_format)

    # file handler
    file_handler = logging.FileHandler("log/monitor_model.log")
    file_handler.setFormatter(log_format)

    logger.handlers.clear()
    logger.addHandler(file_handler)
    return logger

python logging basicconfig stdout

# https://stackoverflow.com/a/14058475
import logging
import sys

root = logging.getLogger()
root.setLevel(logging.DEBUG)

handler = logging.StreamHandler(sys.stdout)
handler.setLevel(logging.DEBUG)
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler.setFormatter(formatter)
root.addHandler(handler)

python logging basicConfig+time

logging.basicConfig(filename='my_log_file.log', format='%(asctime)s - %(message)s', level=logging.INFO)

python logging

# Example usage:
# For now, this is how I like to set up logging in Python:

import logging

# instantiate the root (parent) logger object (this is what gets called
# to create log messages)
root_logger = logging.getLogger()
# remove the default StreamHandler which isn't formatted well
root_logger.handlers = []
# set the lowest-severity log message to be included by the root_logger (this
# doesn't need to be set for each of the handlers that are added to the
# root_logger later because handlers inherit the logging level of their parent
# if their level is left unspecified. The root logger uses WARNING by default
root_logger.setLevel(logging.INFO)

# create the file_handler, which controls log messages which will be written
# to a log file (the default write mode is append)
file_handler = logging.FileHandler('/path/to/logfile.log')
# create the console_handler (which enables log messages to be sent to stdout)
console_handler = logging.StreamHandler()

# create the formatter, which controls the format of the log messages
# I like this format which includes the following information:
# 2022-04-01 14:03:03,446 - script_name.py - function_name - Line: 461 - INFO - Log message.
formatter = logging.Formatter('%(asctime)s - %(filename)s - %(funcName)s - Line: %(lineno)d - %(levelname)s - %(message)s')
# add the formatter to the handlers so they get formatted as desired
file_handler.setFormatter(formatter)
console_handler.setFormatter(formatter)

# set the severity level of the console_hander to ERROR so that only messages
# of severity ERROR or higher are printed to the console
console_handler.setLevel(logging.ERROR)

# add the handlers to the root_logger
root_logger.addHandler(file_handler)
root_logger.addHandler(console_handler)


# given the above setup
# running this line will append the info message to the /path/to/logfile.log
# but won't print to the console
root_logger.INFO("A casual message.")
# running this line will append the error message to the /path/to/logfile.log
# and will print it to the console
root_logger.ERROR("A serious issue!")

Python Logging

# importing module
import logging
 
# Create and configure logger
logging.basicConfig(filename="newfile.log",
                    format='%(asctime)s %(message)s',
                    filemode='w')
 
# Creating an object
logger = logging.getLogger()
 
# Setting the threshold of logger to DEBUG
logger.setLevel(logging.DEBUG)
 
# Test messages
logger.debug("Harmless debug Message")
logger.info("Just an information")
logger.warning("Its a Warning")
logger.error("Did you try to divide by zero")
logger.critical("Internet is down")

python logging level

# python logging level
Level: NOTSET > DEBUG > INFO > WARNING > ERROR > CRITICAL
Value:   0    >  10   >  20  >    30   >  40   >  50
  
Logger.setLevel() specifies the lowest-severity log message a logger will
handle, where debug is the lowest built-in severity level and critical is
the highest built-in severity. 

For example, if the severity level is INFO, the logger will handle only INFO,
WARNING, ERROR, and CRITICAL messages and will ignore DEBUG messages.

# logging

# logging
import logging

# log the execution time and a message of an action
logging.basicConfig(filename='fileName.log',
                    level=logging.INFO,
					format='%(levelname)s:%(asctime)s:%(message)s',
					datefmt="%Y-%m-%d %H:%M:%S")

logging.info('ADD TWO NUMBERS')
print(5+5)

# output in console -> 10
# output in fileName.log -> INFO:2021-12-25 17:47:27:ADD TWO NUMBERS
# Logging is a means of tracking events that happen when some software runs. Logging is important for software developing, debugging and running. If you don’t have any logging record and your program crashes, there are very little chances that you detect the cause of the problem.

python logging levels

Logging Levels

CRITICAL
ERROR
WARNING
INFO
DEBUG
NOTSET

logging.basicConfig()

import logging  
  
#Create and configure logger using the basicConfig() function  
logging.basicConfig(filename="newfile.log",  
               format='%(asctime)s %(message)s',  
               filemode='w')  
  
#Creating an object of the logging  
logger=logging.getLogger()  
  
#Setting the threshold of logger to DEBUG  
logger.setLevel(logging.DEBUG)  
  
#Test messages  
logger.debug("This is a harmless debug Message")  
logger.info("This is just an information")  
logger.warning("It is a Warning. Please make changes")  
logger.error("You are trying to divide by zero")  
logger.critical("Internet is down")