Writing custom log handler in python

Question

I am trying to extend RotatingFile Handler to say FooBar.

class FooBar(RotatingFileHandler)  :
    def __init__(self,  filename, mode='a', maxBytes=0,backupCount=0, encoding=None, delay=0) :
        RotatingHandler.__init__(self, filename, mode, maxBytes, backupCount, encoding, delay)

I configure it using

LOGGING = {
  'version': 1,
  'disable_existing_loggers': True,
    'formatters': {
    'verbose': {
      'format': '%(levelname)s %(asctime)s %(module)s %(process)d %(thread)d %(message)s'
        },
      'simple': {
        'format': '%(levelname)s %(asctime)s %(message)s'
        },
      },
    'handlers': {
      'file':{
        'level': 'ERROR',
        'class': 'myhandler.FooBar',
          'formatter': 'simple',
            'filename': '/tmp/cattle.txt',
              'mode': 'a',
              'maxBytes': 16,
                'backupCount' : 100,
                  },


#-- Remaining part truncated ###


logging.config.dictConfig(LOGGING)  ### === ERROR here

When I use it ; I get an error

  File "/usr/lib/python2.7/logging/config.py", line 576, in configure
    '%r: %s' % (name, e))
ValueError: Unable to configure handler 'file': global name 'RotatingHandler' is not defined

The configuration attribute classneeds the fully qualified name of the handler class which in your case is myhandler.FooBar right? But do you import logging.handler.RotatingFileHandler as RotatingFileHandlerin the classes implementation? — Dilettant
– Dilettant, Commented Jun 3, 2016 at 14:15
FooBar is just an example. I want to change behaviour of emit function and copy log file to AWS S3 upon rotate — forvaidya
– forvaidya, Commented Jun 3, 2016 at 14:47
The point was the missing import - cf. ErikR's answer including hints on skipping derivation altogether — Dilettant
– Dilettant, Commented Jun 3, 2016 at 15:05

Community · Accepted Answer · 2017-05-23 12:15:57Z

3

RotatingHandler is not in scope, so you would need something like this to bring it into scope:

from logging.handlers import RotatingFileHandler

However, have a look at this example:

How to log everything into a file using RotatingFileHandler by using logging.conf file?

You may not need to create your own class to accomplish what you want to do.

edited May 23, 2017 at 12:15

CommunityBot

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answered Jun 3, 2016 at 14:17

ErikR

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