[Twisted-Python] Passing arguments while running a twistd application

Jean-Paul Calderone exarkun at divmod.com
Fri Oct 31 09:12:19 EDT 2008

On Fri, 31 Oct 2008 12:42:52 +0100, Terry Jones <terry at jon.es> wrote:
>>>>>> "Adriano" == Adriano Marques <py.adriano at gmail.com> writes:
>Adriano> I have a twisted application, which formely was run with command
>Adriano> line arguments which were used during runtime, eg: I was passing
>Adriano> the path to the log file as argument. Then, I decided to make my
>Adriano> app run through twistd as a tac file but then I'm not able to pass
>Adriano> command line arguments anymore. Is there any way to overcome this
>Adriano> issue?
>I also ran into this, and asked for some way to pass args but got told
>(paraphrasing, from memory) that that's not the way to do it...

To add slightly to this correct answer:

The "tac" in a .tac file stands for "Twisted Application Configuration".
The reason you cannot pass extra arguments on the command line when using
a .tac file is that the intent is for all configuration to be in the .tac
file.  So if this isn't appropriate for your application, a twistd plugin
is probably a better solution.

>The way to do it seems to be to convert your application to be a Twisted
>plugin. It's not too hard.  Then you make sure there's a twisted/plugins
>dir accessible from your path (with no __init__.py files in/under it). Then
>twistd will find your plugin (just run twistd with no options and you
>should see your plugin name listed at the bottom among the commands). Then
>you can add options processing by subclassing the Options class in
>Sorry to be so terse - no time. The above does work though, and seems to be
>the Twisted way. Rough (untested) guideline code below.
>from zope.interface import implements
>from twisted.python import usage
>from twisted.plugin import IPlugin
>from twisted.application.service import IServiceMaker
>from ???? import myservice
>class Options(usage.Options):
>    optFlags = [
>        ['verbose', None, 'If True, be verbose.'],
>    ]
>    optParameters = [
>        ['port', 'p', '0', 'The port number to listen on.'],
>    ]
>class MyServiceMaker(object):
>    implements(IServiceMaker, IPlugin)
>    # The tapname will appear in the output of twistd when run with no args.
>    # Use twistd -n my-plugin-name
>    # to invoke it.
>    tapname = 'my-plugin-name'
>    description = 'My snazzy service.'
>    options = Options
>    def makeService(self, options):
>        return myservice(
>            options['port'], options['verbose'])
>serviceMaker = MyServiceMaker()

Fortunately, in case the above misses anything or you'd like any parts
of it explained, there is documentation about writing plugins. :)



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