how do I save flask app logs separately per day instead of one giant file

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


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

formatter = logging.Formatter('[%(asctime)s] %(levelname)s: %(message)s', datefmt='%Y-%m-%d %H:%M:%S')

handler = TimedRotatingFileHandler(os.path.join('./', 'custom_log.log'), 
                        when='midnight', backupCount=7)
handler.setLevel(logging.INFO)
handler.setFormatter(formatter)

logger.addHandler(handler)

logger.info("Info")
logger.warning("Warning")
logger.error("Error")

from flask import Flask
import logging
from logging.handlers import RotatingFileHandler

app = Flask(__name__)

if __name__ == '__main__':
    handler = RotatingFileHandler('test.log', maxBytes=12000, backupCount=5)
    handler.setLevel(logging.INFO)
    app.logger.addHandler(handler)
    app.run()