finger_plugin.py

# ==== twisted/plugins/finger_plugin.py ====
# This snippet shows how to configure Twisted plugins to use custom logging.
# This is a modification of a 'finger' example by Chris Miles at
# http://chrismiles.livejournal.com/23399.html
#
# It's kind of a dirty monkey patching hack, but I don't know how to
# configure logging in plugins until this ticket is resolved:
# http://twistedmatrix.com/trac/ticket/638
# 
# I change logging from the default LogFile to DailyLogFile, and also
# install a custom log observer.

# - Zope modules -
from zope.interface import implements

# - Twisted modules -
from twisted.python import usage
from twisted.application.service import IServiceMaker
from twisted.plugin import IPlugin
from twisted.python.log import ILogObserver, FileLogObserver, textFromEventDict
from twisted.python.logfile import DailyLogFile
from twisted.python import util

# - Finger modules -
from finger import finger

class Options(usage.Options):
    synopsis = "[options]"
    longdesc = "Make a finger server."
    optParameters = [
        ['file', 'f', '/etc/users'],
        ['templates', 't', '/usr/share/finger/templates'],
        ['ircnick', 'n', 'fingerbot'],
        ['ircserver', None, 'irc.freenode.net'],
        ['pbport', 'p', 8889],
        # adding new 'logfile' option. The original -l options of twistd
        # will not be used
        ['logfile', 'l', 'finger.log'],
    ]
    
    optFlags = [['ssl', 's']]


class MyLogObserver(FileLogObserver):
    # This is my custom log observer. What it does is it avoids printing
    # the 'system' component of the log
    # It can basically do whatever you want with your logging
    def emit(self, eventDict):
        text = textFromEventDict(eventDict)
        if text is None:
            return
        timeStr = self.formatTime(eventDict['time'])
        util.untilConcludes(self.write, timeStr + " " +  text.replace("\n", "\n\t") + "\n")
        util.untilConcludes(self.flush)


# wrapper for the setServiceParent method of t.a.s.Service
def wrap_setServiceParent(func, config):
    def decorator(app):
        logfile = DailyLogFile(config["logfile"], "/tmp")
        app.setComponent(ILogObserver, MyLogObserver(logfile).emit)
        return func(app)
    return decorator

class MyServiceMaker(object):
    implements(IServiceMaker, IPlugin)
    
    tapname = "finger"
    description = "Finger server."
    options = Options
    
    def makeService(self, config):
        s = finger.makeService(config)
        
        # Here's the monkey patching trick:
        # we hook into setServiceParent of the service to execute some code
        # in the context where twisted application object is accessible
        s.setServiceParent = wrap_setServiceParent(s.setServiceParent, config)
        return s

serviceMaker = MyServiceMaker()