Answers for "what are handlers in logging python"

python logging to file

import logging
import sys

logger = logging.getLogger()
logger.setLevel(logging.INFO)
formatter = logging.Formatter('%(asctime)s | %(levelname)s | %(message)s', 
                              '%m-%d-%Y %H:%M:%S')

stdout_handler = logging.StreamHandler(sys.stdout)
stdout_handler.setLevel(logging.DEBUG)
stdout_handler.setFormatter(formatter)

file_handler = logging.FileHandler('logs.log')
file_handler.setLevel(logging.DEBUG)
file_handler.setFormatter(formatter)

logger.addHandler(file_handler)
logger.addHandler(stdout_handler)

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.