Automatically delete old Python log files

Question

I have a Python program that runs daily. I'm using the logging module with FileHandler to write logs to a file. I would like each run's logs to be in its own file with a timestamp. However, I want to delete old files (say > 3 months) to avoid filling the disk.

I've looked at the RotatingFileHandler and TimedRotatingFileHandler but I don't want a single run's logs to be split across multiple files, even if a single run were to take days. Is there a built-in method for that?

Answer 1

The logging module has a built in TimedRotatingFileHandler:

# import module
from logging.handlers import TimedRotatingFileHandler
from logging import Formatter

# get named logger
logger = logging.getLogger(__name__)

# create handler
handler = TimedRotatingFileHandler(filename='runtime.log', when='D', interval=1, backupCount=90, encoding='utf-8', delay=False)

# create formatter and add to handler
formatter = Formatter(fmt='%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler.setFormatter(formatter)

# add the handler to named logger
logger.addHandler(handler)

# set the logging level
logger.setLevel(logging.INFO)

# --------------------------------------

# log something
logger.info("test")

Old logs automatically get a timestamp appended.

Every day a new backup will be created.

If more than 91 (current+backups) files exist the oldest will be deleted.

Answer 2

import logging
import time
from logging.handlers import RotatingFileHandler

logFile = 'test-' + time.strftime("%Y%m%d-%H%M%S")+ '.log'

logger = logging.getLogger('my_logger')
handler = RotatingFileHandler(logFile, mode='a', maxBytes=50*1024*1024, 
                                 backupCount=5, encoding=None, delay=False)
logger.setLevel(logging.DEBUG)
logger.addHandler(handler)

for _ in range(10000):
    logger.debug("Hello, world!")