34

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.

Skitzafreak
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  • How are you importing datetime? This could be an error not getting handled correctly due to the common mistake of using `datetime.now()` instead of `datetime.datetime.now()`. – Richard Dunn Aug 01 '17 at 19:31
  • ......I suppose I am not importing datetime. Though I did just change my config file to `datetime.datetime.now()` and still got the same error. Would I be importing it in my Python script? – Skitzafreak Aug 01 '17 at 19:33
  • Yeah, try putting `from datetime import datetime` at the top of your script. – Richard Dunn Aug 01 '17 at 19:43
  • Hold on. Is that in the **logging.conf** file? That's not a python script, that just text... – Richard Dunn Aug 01 '17 at 19:46
  • Yeah I realize the `logging.conf` file is just text. That's why I am asking if anyone knows a way to in the configuration file set the Date as the file name. Or is this a case where instead of using a configuration file I should be hard coding it in the script? – Skitzafreak Aug 01 '17 at 19:49
  • See my answer below, though to be fair, @nofinator's answer is the right way to go... – Richard Dunn Aug 01 '17 at 19:55

12 Answers12

21

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.

Dror Av.
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10

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--

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.

nofinator
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    Not sure if they works in the way I need it to. From my understanding after looking at the links you provided the `TimedRotatingFileHandler` is for when you are planning on having a program running for multiple days and you want separate log files for each day. In my case my program may be getting used 30 minutes to an hour for each use, but I still need to be able to track the date of when it is used. – Skitzafreak Aug 01 '17 at 19:59
6

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

shaik moeed
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Abhishek
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5

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')
NotMuchTalent
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4

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.

user2165
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Vijay Jangir
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3

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.

Xnot
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1

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'))
Richard Dunn
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0

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.

Alexander
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0

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

Delgan
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Joy
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    Imagine your program running for two days. Then the file name would remain the same. That would beat the purpose of having a date in the filename. – nurettin Mar 17 '23 at 06:57
0

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)
Ophir Carmi
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ibra
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0

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)
Yasiru Ayeshmantha
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0

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)
Niall Nolan
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