Maintaining Logging and/or stdout/stderr in Python Daemon

Question

Every recipe that I\'ve found for creating a daemon process in Python involves forking twice (for Unix) and then closing all open file descriptors. (See http://www.jejik.com

Answer 1

You can simplify the code for this if you set up your logging handler objects separately from your root logger object, and then add the handler objects as an independent step rather than doing it all at one time. The following should work for you.

import daemon
import logging

logger = logging.getLogger()
logger.setLevel(logging.DEBUG)
fh = logging.FileHandler("./foo.log")
logger.addHandler(fh)

context = daemon.DaemonContext(
   files_preserve = [
      fh.stream,
   ],
)

logger.debug( "Before daemonizing." )
context.open()
logger.debug( "After daemonizing." )