Python logging - new log file every time applicati

Question

I've been doing research and am having an extremely difficult time completing what I'm hoping to achieve. Currently, this is what I have (testlog.py)

import logging
import logging.handlers

filename = "example.log"

logger = logging.getLogger()
logger.setLevel(logging.DEBUG)
formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")

handler = logging.handlers.RotatingFileHandler(filename, mode = 'w', backupCount = 5)
handler.setLevel(logging.DEBUG)
handler.setFormatter(formatter)
logger.addHandler(handler)

ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)
ch.setFormatter(formatter)
logger.addHandler(ch)

for i in range(10):
   logger.debug("testx") #where I alternate x from 1 thru 9 to see output

It currently successfully prints out to the console and to example.log, which is what I want.

Every time I run it, it makes a new file and replaces the old example.log like so:

run with logger.debug("test1")

example.log contains test1 10 times like it should

run with logger.debug("test2")

it rewrites example.log to contain test2 10 times etc...

However, I would like for the code to make a new log file every time I run the program so that I have

example.log

example.log1

example.log2

...

example.log5

In conclusion, I'd like for this file to print the log message to the console, to the log file, and I would like a new log file (up to *.5) whenever I run the program. Thanks!

Answer 1

logging.handlers.RotatingFileHandler rotates your logs based either on size or on date, but you can force it to rotate using RotatingFileHandler.doRollover() so something like:

import logging.handlers
import os

filename = "example.log"

# your logging setup

should_roll_over = os.path.isfile(filename)
handler = logging.handlers.RotatingFileHandler(filename, mode='w', backupCount=5)
if should_roll_over:  # log already exists, roll over!
    handler.doRollover()

# the rest of your setup...

Should work like a charm.