Python logger dynamic filename

Question

I want to configure my Python logger in such a way so that each instance of logger should log in a file having the same name as the name of the logger itself.

e.g.:

log_hm = logging.getLogger('healthmonitor')
log_hm.info("Testing Log") # Should log to /some/path/healthmonitor.log

log_sc = logging.getLogger('scripts')
log_sc.debug("Testing Scripts") # Should log to /some/path/scripts.log

log_cr = logging.getLogger('cron')
log_cr.info("Testing cron") # Should log to /some/path/cron.log

I want to keep it generic and dont want to hardcode all kind of logger names I can have. Is that possible?

Asked By: sharjeel

||

Source

Answer 1

How about simply wrap the handler code in a function:

import os
def myLogger(name):
    logger = logging.getLogger(name)
    logger.setLevel(logging.DEBUG)
    handler = logging.FileHandler(os.path.join('/some/path/', name + '.log'), 'w')
    logger.addHandler(handler)
    return logger

log_hm = myLogger('healthmonitor')
log_hm.info("Testing Log") # Should log to /some/path/healthmonitor.log

To prevent creating duplicate handlers, care needs to be taken to ensure that myLogger(name) is only called once per name. Usually that means putting myLogger(name) inside

if __name__ == '__main__':
    log_hm = myLogger('healthmonitor')

of the main script.

Answered By: unutbu

Answer 2

import os
import logging

class MyFileHandler(object):

    def __init__(self, dir, logger, handlerFactory, **kw):
        kw['filename'] = os.path.join(dir, logger.name)
        self._handler = handlerFactory(**kw)

    def __getattr__(self, n):
        if hasattr(self._handler, n):
            return getattr(self._handler, n)
        raise AttributeError, n

logger = logging.getLogger('test')
logger.setLevel(logging.INFO)
handler = MyFileHandler(os.curdir, logger, logging.FileHandler)
logger.addHandler(handler)
logger.info('hello mylogger')

Answered By: mg.

Answer 3

The approach used in the above solution is correct, but that has issue of adding duplicate handlers when called more than once. Here is the improved version.

import os
def getLogger(name):
    # logger.getLogger returns the cached logger when called multiple times
    # logger.Logger created a new one every time and that avoids adding
    # duplicate handlers 
    logger = logging.Logger(name)
    logger.setLevel(logging.DEBUG)
    handler = logging.FileHandler(os.path.join('/some/path/', name + '.log'), 'a')
    logger.addHandler(handler)
    return logger

def test(i):
  log_hm = getLogger('healthmonitor')
  log_hm.info("Testing Log %s", i) # Should log to /some/path/healthmonitor.log

test(1)
test(2)

Answered By: Anand Chitipothu

Answer 4

I’m trying to implement this solution with both dynamic path and file name but nothing is written in the file.

class PaymentViewSet(viewsets.ModelViewSet):
serializer_class = PaymentSerializer
queryset = Payment.objects.all()
permission_classes = [IsAuthenticated]

def paymentLog(self, paymentSerializer):
    # file : logs/${terminalName}/${%Y-%m}-payments.log
    terminalName = TerminalSerializer(Terminal.objects.get(pk=paymentSerializer.data.get("terminal"))).data.get("name")
    filePath = os.path.join(settings.LOG_PATH, terminalName)
    if not os.path.exists(filePath):
        os.makedirs(filePath)
    fileName = filePath + "/" + datetime.now().strftime("%Y-%m") +'-payments.log'
    handler = logging.FileHandler(fileName)
    handler.setFormatter('%(asctime)s [PAYMENT]- %(message)s')

    logger = logging.Logger("payment")
    logger.setLevel(logging.INFO)
    logger.addHandler(handler)
    # logger.propagate = False
    logging.info(paymentSerializer.data)

    # printout()


def create(self, request, *args, **kwargs):
    serializer = self.get_serializer(data=request.data)
    serializer.is_valid(raise_exception=True)
    self.perform_create(serializer)

    # log here
    self.paymentLog(serializer)

    headers = self.get_success_headers(serializer.data)
    return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

The path and file are created like intended but the log never writes.

Answered By: Fabien B

Python logger dynamic filename

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