Python Logging - Set Date as Filename

Question

I am working on implementing logging within my Python project and have hit a bit of a snag. I am trying to set up my logging such that the Handlers, and Formatters are all organized into a configuration file. What I am trying to do at the moment is to set up my fileHandler such that it will create a log file that looks something like this: YYYY_MM_DD.log obviously with the Y's representing the year, M's representing the month, and D's representing the day.

This is what I have attempted with my config file:

[loggers] keys=root,MainLogger  [handlers] keys=fileHandler, consoleHandler  [formatters] keys=logFormatter, consoleFormatter  [logger_root] level=DEBUG handlers=fileHandler  [logger_MainLogger] level=DEBUG handlers=fileHandler, consoleHandler qualname=MainLogger propagate=0  [handler_consoleHandler] class=StreamHandler level=DEBUG formatter=consoleFormatter args=(sys.stdout,)  [handler_fileHandler] class=FileHandler level=DEBUG formatter=logFormatter args=(datetime.now().strftime('%Y_%m_%d.log'), 'a')  [formatter_logFormatter] format=%(asctime)s | %(levelname)-8s | %(lineno)04d | %(message)s  [formatter_consoleFormatter] format=%(asctime)s | %(levelname)-8s | %(fillname)s-%(funcName)s-%(lineno)04d | %message)s 

The file I am using to test the configuration is pretty simple:

import logging import logging.config  logging.config.fileConfig('logging.conf') logger = logging.getLogger('MainLogger') logger.debug("TEST") 

The specific error I am getting at the moment is:

configparser.InterpolationSyntaxError: '%' must be followed by '%' or '(', found: "%Y_%m_%d.log'), 'a')" 

I've tried changing the %Y, %m, and %d as the error says, but that doesn't fix the problem. How do I go about setting up the config file so that my log files look the way I want them to?

I should note when I change the filename to test.log everything worked fine, so this is the only error I seem to be having with this.

Answer 1

You can't use datetime in a config file, as it doesn't know what it means. You can however add the Filehandler in the python file itself:

import logging.config from datetime import datetime  logging.config.fileConfig('aaa.conf') logger = logging.getLogger('MainLogger')  fh = logging.FileHandler('{:%Y-%m-%d}.log'.format(datetime.now())) formatter = logging.Formatter('%(asctime)s | %(levelname)-8s | %(lineno)04d | %(message)s') fh.setFormatter(formatter)  logger.addHandler(fh) logger.debug("TEST") 

This way you can set the date as the file name in the handler.

This is the config file, note that you had a typo in the last formatter, you put fillname instead of filename and you forgot ( in message.

[loggers] keys=root,MainLogger  [handlers] keys=consoleHandler  [formatters] keys=consoleFormatter  [logger_root] level=DEBUG handlers=consoleHandler  [logger_MainLogger] level=DEBUG handlers=consoleHandler qualname=MainLogger propagate=0  [handler_consoleHandler] class=StreamHandler level=DEBUG formatter=consoleFormatter args=(sys.stdout,)  [formatter_consoleFormatter] format=%(asctime)s | %(levelname)-8s | %(filename)s-%(funcName)s-%(lineno)04d | %(message)s 

This Should work just fine.