How To Refer To A Standard Library In A Logging Configuration File?

I need to use a constant defined in the standard library socket in a logging configuration file. Problem, when reading the config file with logging.config.fileConfig() it ends with

Solution 1:

As documented in this section of the docs, the values are evaluated in the logging package's namespace. Hence, you can do something like this:

import logging
import socket

# The next line allows 'socket' in the logging package's namespace to pick up
# the stdlib socket module
logging.socket = socket
...
# when the config file is processed, it should work as expected
logging.config.fileConfig(...)
# remove the mapping from the logging package, as not needed any more
# (optional)
del logging.socket

Solution 2:

First solution (should work but doesn't)

Well here there is a partial answer: https://docs.python.org/3.4/library/logging.config.html#access-to-external-objects

So I tried this:

args=('/dev/log','mathmaker','ext://socket.SOCK_STREAM')

But it does not work:

Traceback (most recent call last):
  File "/usr/lib/python3.4/logging/__init__.py", line 1878, in shutdown
    h.close()
  File "/usr/lib/python3.4/logging/handlers.py", line 857, in close
    self.socket.close()
AttributeError: 'SysLogHandler' object has no attribute 'socket'

It's like python expects the 'external' object to be an attribute of the class declared in the handler section (e.g. here: class=logging.handlers.SysLogHandler).

Second solution (but requires to turn the config file into yaml):

So, as the mechanism that seems dedicated to solve this problem does not work, I have tried with a configuration file written in yaml, and now it works. It requires to add a dependency (python-yaml or python3-yaml for ubuntu users...) and to load the configuration file as a dictionary:

with open(settings.logging_conf_file) as f:
    logging.config.dictConfig(yaml.load(f))

and this way, it works.

Here is the same configuration file turned into working yaml (and notice that: 1. the import of socket is not required in the main script, looks like python will by itself 'magically' deal with the import; and 2. apart from the fact that yaml is easier to read than the old plain text config file, it also allows to define the keywords in a more readable way):

version: 1

formatters:
    rawMessageFormatter:
        format: '%(message)s'
        datefmt: ''
    defaultFormatter:
        format: '%(asctime)s.%(msecs)d %(filename)s: %(funcName)s: %(message)s'
        datefmt: '%Y/%m/%d %H:%M:%S'

handlers:
    nullHandler:
        class: logging.NullHandler
    mainHandler:
        class: logging.handlers.SysLogHandler
        level: INFO
        formatter: defaultFormatter
        address: '/dev/log'
        facility: 'myapp'
        socktype: ext://socket.SOCK_DGRAM

loggers:
    root:
        level: INFO
        handlers: [nullHandler]
    mainLogger:
        level: DEBUG
        handlers: [mainHandler]
        qualname: mainLogger