Question

as you might know the python logging module supports the definition of *kwargs to customize log entries. This appears to be not supported for logging exceptions.

My Question: Is there an easy way to use custom kwargs with logging.exception?

A minimal example follows:

import logging
import logging.handlers

def create_logger(): 
    """ initialize logging using sys log

    """
    logger = logging.getLogger()

    form = '%(asctime)s [%(levelname)-8s] %(xyz)s %(message)s'
    local_log_handler = logging.handlers.SysLogHandler(address='/dev/log')
    formatter = logging.Formatter(form)
    local_log_handler.setFormatter(formatter)

    logger.addHandler(local_log_handler)
    return logger

log = create_logger()
try:
    raise AttributeError("whatever")
except:
    log.warn('Alarm! Fire!', extra={'xyz':'POLICE'})
    log.exception('')

Output:

Traceback (most recent call last):
  File "logexample.py", line 27, in <module>
    log.exception('')
  File "/usr/lib/python2.7/logging/__init__.py", line 1172, in exception
    self.error(msg, exc_info=1, *args)
  File "/usr/lib/python2.7/logging/__init__.py", line 1166, in error
    self._log(ERROR, msg, args, **kwargs)
  File "/usr/lib/python2.7/logging/__init__.py", line 1258, in _log
    self.handle(record)
  File "/usr/lib/python2.7/logging/__init__.py", line 1268, in handle
    self.callHandlers(record)
  File "/usr/lib/python2.7/logging/__init__.py", line 1308, in callHandlers
    hdlr.handle(record)
  File "/usr/lib/python2.7/logging/__init__.py", line 748, in handle
    self.emit(record)
  File "/usr/lib/python2.7/logging/handlers.py", line 791, in emit
    msg = self.format(record) + '\000'
  File "/usr/lib/python2.7/logging/__init__.py", line 723, in format
    return fmt.format(record)
  File "/usr/lib/python2.7/logging/__init__.py", line 467, in format
    s = self._fmt % record.__dict__
KeyError: 'xyz'

Syslog:

Jul 30 14:56:27 localhost 2012-07-30 14:56:27,131 [WARNING ] POLICE Alarm! Fire!

PS: A little background, I am writing a process with threading and I want to log information in the following manner:

[app-thread1]
[app-thread2]
…

Answer 1

You can just use e.g.

logger.error('Message with %s', 'args', exc_info=1, extra={...})