Unable to name log file with custom timestamp format using TimedRotatingFileHandler

Question

Is it possible to create log files with custom date format, using TimedRotatingFileHandler?

import logging
from logging.handlers import TimedRotatingFileHandler
import os
from datetime import datetime
import time

logger = logging.getLogger('my_logger')
logger.setLevel(logging.DEBUG)

log_dir = 'logs'
log_file = os.path.join(log_dir, datetime.now().strftime('%Y%m%d-%H%M%S') + f'_.log')

handler = TimedRotatingFileHandler(log_file, when='s', interval=1, backupCount=0)
handler.setFormatter(logging.Formatter('%(asctime)s - %(levelname)s - %(message)s'))
logger.addHandler(handler)

i = 0
while True:
    logger.info(i)
    print(i)
    time.sleep(1)
    i += 1

Produces

20230810-100547_.log.2023-08-10_10-05-47
20230810-100547_.log.2023-08-10_10-05-48
20230810-100547_.log

Instead of

20230810-100547_.log
20230810-100548_.log
20230810-100549_.log

Does one need to reset the handler after midnight (is it even possible)? Does not seem elegant.

There seem to be a namer attribute in logging handlers

Answer 1

There is rotation_filename method and you can assign it to namer function. It will change name of your log file during rotation. Working code should look like this:

import logging
from logging.handlers import TimedRotatingFileHandler
import os
from datetime import datetime
import time

def namer(self):
    now = datetime.now()
    log_dir = './logs'
    return os.path.join(log_dir, datetime.now().strftime('%Y%m%d-%H%M%S') + f'_.log')

logger = logging.getLogger('my_logger')
logger.setLevel(logging.DEBUG)

log_dir = './logs'
log_file = os.path.join(log_dir, datetime.now().strftime('%Y%m%d-%H%M%S') + f'_.log')

handler = TimedRotatingFileHandler(log_file, when='s', interval=1, backupCount=0)
handler.rotation_filename = namer
handler.setFormatter(logging.Formatter('%(asctime)s - %(levelname)s - %(message)s'))
logger.addHandler(handler)


i = 0
while True:
    logger.info(i)
    print(i)
    time.sleep(1)
    i += 1