Logging in Python - Principles

Log early, Log often

By default python supports logging

import logging

It can output up to 5 logging levels.

logging.debug('debug')
logging.info('test')
logging.warning('warning')
logging.error('error')
logging.critical('critical')

By default, it shows warning and error and critical logs.

For logging each module, you have to import it first.

import logger

then it is best if you instantiate it like this:

logger = logging.getlogger(__name__)
looger.info('log from another module')

Calm code logger

import logging 
from rich.logging import RichHandler
logger = logging.getLogger(__name__)
# the handler determines where the logs go: stdout/file 
shell_handler = RichHandler() 
file_handler = logging.FileHandler("debug.log")
 
logger.setLevel(logging.DEBUG)
shell_handler.setLevel(logging.DEBUG)
file_handler.setLevel(logging.DEBUG) 
 
# the formatter determines what our logs will look like 
 
fmt_shell = '%(message)s' 
fmt_file = '%(levelname)s %(asctime)s [%(filename)s:%(funcName)s:%(lineno)d] %(message)s' 
 
shell_formatter = logging.Formatter(fmt_shell) 
file_formatter = logging.Formatter(fmt_file) 
# here we hook everything together
shell_handler.setFormatter(shell_formatter)
file_handler.setFormatter(file_formatter)
 
logger.addHandler(shell_handler)
logger.addHandler(file_handler)

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