Python Logging – Set Date as Filename

This uses content from your config file, but does not access the file directly. You create your own filehandler and then add it to the logger.

import logging
from datetime import datetime

# Create logger.
logger = logging.getLogger('MainLogger')
logger.setLevel(logging.DEBUG)

# Create filehandler with desired filename.
fh = logging.FileHandler('{}.log'.format(datetime.now().strftime('%Y_%m_%d')))
fh.setLevel(logging.DEBUG)
log_formatter = logging.Formatter('%(asctime)s | %(levelname)-8s | %(lineno)04d | %(message)s')
fh.setFormatter(log_formatter)

# Add filehandler to logger.
logger.addHandler(fh)

Note that a (append) is the default mode parameter for a FileHandler.

Perhaps you can use Python’s TimedRotatingFileHandler instead. You can set the interval to create a new log file every day with the date as the suffix.

Documentation–

• Python 2: https://docs.python.org/2/library/logging.handlers.html#timedrotatingfilehandler
• Python 3: https://docs.python.org/3/library/logging.handlers.html#timedrotatingfilehandler

Note that the current day’s log file won’t have a date. This file handler only adds the date suffix when a new day starts.

Also, the suffix it uses is “%Y-%m-%d”, which is a little different than what you want. But there’s a SO question here about how you can alter that.

Maybe try changing the name after you’ve loaded the config file:

from datetime inport datetime

logging.config.fileConfig('logging.conf')
logging.basicConfig(filename = datetime.now().strftime('%Y_%m_%d.log'))

This worked for me.

Update this,

args=(datetime.now().strftime('%Y_%m_%d.log'), 'a')

with this,

args=(__import__("datetime").datetime.now().strftime('%Y_%m_%d.log'), 'a')

Reference (Example no 3): http://python-reference.readthedocs.io/en/latest/docs/functions/eval.html

This also works

from datetime import datetime
log_file = str(datetime.utcnow().strftime('%m_%d_%Y_%I_%M_%S')) + '.log'
logging.basicConfig(filename=log_file, format='%(levelname)s | %(asctime)s | %(message)s', datefmt='%m/%d/%Y %I:%M:%S %p', level=logging.DEBUG)

Logfile name:04_30_2018_10_03_01.log

Using double ‘%’-characters in the format string in combination with the approach suggested by Abhishek led to a working solution in my case (Python 3.5):

The filehandler in the config file should then look similar to this one:

[handler_fileHandler]
class=FileHandler
level=DEBUG
formatter=defaultFormatter
args=(__import__("datetime").datetime.now().strftime('/your_path/your_file_name_%%Y-%%m-%%d_%%H-%%M-%%S.log'), 'a')

This post is old, but for anyone still struggling with any such issue of dynamic naming of filenames from logging.conf
while calling logging.config.fileConfig() you can pass the variables and use them in the logging configuration file.
Eg:

logging.conf

args=('my_log_%(date)s.log','w')

python.py

import logging.config
logging.config.fileConfig('logging.conf', defaults={'date':datetime.now()})

You might wanna format the date while using it here.

In the same fashion, any number of variables could be used.

My solution for my python product is to keep the configuration file with a path to a fixed log file such as:

[handler_fileHandler] <br>
class=FileHandler <br>
level=DEBUG <br>
formatter=defaultFormatter <br>
args=('../projectnamespace/data/logs/logfile.log',)

and for each day I will move the log file to older folder logs so by doing that I avoid having a huge log files for later reading….

log_path = str((Path(__file__).parent / 'data' / 'logs' / 'logfile.log').absolute())

log_file_date_created = None 
if platform.system() == 'Windows':
    log_file_date_created = datetime.fromtimestamp(os.path.getctime(log_path))
else:
    stat = os.stat(log_path)
    try:
        log_file_date_created = stat.st_birthtime
    except AttributeError:
        # running in Linux. No easy way to get creation dates here,
        # we get when its content was last modified.
        return stat.st_mtime

if log_file_date_created != None and abs(datetime.today().day - log_file_date_created.day) >= 1:
    file_date = str(log_file_date_created.strftime("%m_%d_%Y")) + '_logfile.log'
    log_path_new_name = str((Path(__file__).parent / 'data' / 'logs' / 'older' /  file_date ).absolute())
    os.replace(log_path, log_path_new_name)

I wanted to keep all of my logging configurable through the config file and wasn’t satisfied with the answers here manually adding the handler through the code. The solution I came up with is to create a handler class inheriting FileHandler which appends the date to the filename parameter before calling the FileHandler constructor:

import os
from logging import FileHandler
from datetime import datetime

class TimestampedFileHandler(FileHandler):
    def __init__(self, filename, mode='a', encoding=None, delay=False):
        filename, extension = os.path.splitext(filename)
        filename = f"{filename}_{datetime.now().strftime('%Y-%m-%d_%H-%M-%S')}{extension}"
        FileHandler.__init__(self, filename, mode, encoding, delay)

You can then use the TimestampedFileHandler in your config file and set its level, formatter, and parameters together with the other handlers.

I created class called LoggingService and use it’s in other python file

import logging
from logging.handlers import RotatingFileHandler
from datetime import datetime

class LoggingService:

    def namer(name):
        now = datetime.now()
        date_time = now.strftime("%Y-%m-%d")
        return name[:-1] + date_time +"."+name[-1:]
      

    LOG_FORMAT = "%(levelname)s %(asctime)s - %(name)s - %(message)s"
    log_file = "your inital log file location"

    rotate_handler = RotatingFileHandler(
        filename=log_file,
        mode='a',
        maxBytes=256,
        backupCount=8,
        encoding=None,
        delay=False
    )

    logging.basicConfig(
        level=logging.DEBUG,
        format=LOG_FORMAT,
        datefmt='%m/%d/%Y %I:%M:%S %p',
        handlers=[rotate_handler]
    )

    rotate_handler.namer = namer

    @staticmethod
    def get_logger(name):
        return logging.getLogger(name)

My solution is to use f strings.
Place f into the ‘filename’ parameter in your config and add {date.today()} or {datetime.now()}.

import logging
from datetime import date, datetime

logging.basicConfig(filename=f"C:\Users\...\my_log{date.today()}.log",
                    encoding='utf-8', format='%(asctime)s - %(message)s', level=logging.INFO)