Python Other

Logging

Simple logging

• logging
• basicConfig

import logging

logging.debug("debug") 
logging.info("info") 
logging.warning("warning") 
logging.error("error")
logging.critical("critical")

logging.log(logging.WARNING, "another warning")
logging.log(40, "another error")

WARNING:root:warning
ERROR:root:error
CRITICAL:root:critical
WARNING:root:another warning
ERROR:root:another error

• Written on STDERR

Simple logging - set level

import logging
 
logging.basicConfig(level = logging.INFO)
 
logging.debug("debug") 
logging.info("info") 
logging.warning("warning") 
logging.error("error")
logging.critical("critical")

INFO:root:info
WARNING:root:warning
ERROR:root:error
CRITICAL:root:critical

Simple logging to a file

import logging
import time
 
logging.basicConfig(level = logging.INFO, filename = time.strftime("my-%Y-%m-%d.log"))
 
logging.debug("debug") 
logging.info("info") 
logging.warning("warning") 
logging.error("error")
logging.critical("critical")

Simple logging format

import logging
    
logging.basicConfig( format = '%(asctime)s  %(levelname)-10s %(processName)s  %(name)s %(message)s')
    
logging.debug("debug") 
logging.info("info") 
logging.warning("warning") 
logging.error("error")
logging.critical("critical")

Simple logging change date format

import logging
 
logging.basicConfig( format = '%(asctime)s  %(levelname)-10s %(processName)s  %(name)s %(message)s', datefmt =  "%Y-%m-%d-%H-%M-%S")
 
logging.debug("debug") 
logging.info("info") 
logging.warning("warning") 
logging.error("error")
logging.critical("critical")

2020-04-22-18-59-16  WARNING    MainProcess  root warning
2020-04-22-18-59-16  ERROR      MainProcess  root error
2020-04-22-18-59-16  CRITICAL   MainProcess  root critical

getLogger

• getLogger
• FileHandler
• StreamHandler

import logging
 
logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)
 
fh = logging.FileHandler('my.log')
fh.setLevel(logging.INFO)
fh.setFormatter( logging.Formatter('%(asctime)s - %(name)s - %(levelname)-10s - %(message)s') )
logger.addHandler(fh)
 
 
sh = logging.StreamHandler()
sh.setLevel(logging.DEBUG)
sh.setFormatter(logging.Formatter('%(asctime)s - %(levelname)-10s - %(message)s'))
logger.addHandler(sh)
 
 
 
log = logging.getLogger(__name__)
log.debug("debug") 
log.info("info") 
log.warning("warning") 
log.error("error")
log.critical("critical")

Time-based logrotation

• TimedRotatingFileHandler

import logging
import logging.handlers

log_file = "my.log"

logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)

ch = logging.handlers.TimedRotatingFileHandler(log_file, when='M', backupCount=2)
ch.setLevel(logging.INFO)
ch.setFormatter( logging.Formatter('%(asctime)s - %(name)s - %(levelname)-10s - %(message)s') )
logger.addHandler(ch)


log = logging.getLogger(__name__)
log.debug("debug")
log.info("info")
log.warning("warning")
log.error("error")
log.critical("critical")

• S - seconds
• M - minutes
• H - hours
• D - days
• docs

Size-based logrotation

import logging
import logging.handlers

log_file = "my.log"

logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)

ch = logging.handlers.RotatingFileHandler(log_file, maxBytes=100, backupCount=2)
ch.setLevel(logging.INFO)
ch.setFormatter( logging.Formatter('%(asctime)s - %(name)s - %(levelname)-10s - %(message)s') )
logger.addHandler(ch)


log = logging.getLogger(__name__)
log.debug("debug")
log.info("info")
log.warning("warning")
log.error("error")
log.critical("critical")