Deploying a Web.py application with WSGI, several servers

Question

I've created a web.py application, and now that it is ready to be deployed, I want to run in not on web.py's built-in webserver. I want to be able to run it on different webservers, Apache or IIS, without having to change my application code. This is where WSGI is supposed to come in, if I understand it correctly.
However, I don't understand what exacly I have to do to make my application deployable on a WSGI server? Most examples assume you are using Pylons/Django/other-framework, on which you simply run some magic command which fixes everything for you.
From what I understand of the (quite brief) web.py documentation, instead of running web.application(...).run(), I should use web.application(...).wsgifunc(). And then what?

Answer 1

Exactly what you need to do to host it with a specific WSGI hosting mechanism varies with the server.

For the case of Apache/mod_wsgi and Phusion Passenger, you just need to provide a WSGI script file which contains an object called 'application'. For web.py 0.2, this is the result of calling web.wsgifunc() with appropriate arguments. For web.py 0.3, you instead use wsgifunc() member function of object returned by web.application(). For details of these see mod_wsgi documentation:

http://code.google.com/p/modwsgi/wiki/IntegrationWithWebPy

If instead you are having to use FASTCGI, SCGI or AJP adapters for a server such as Lighttpd, nginx or Cherokee, then you need to use 'flup' package to provide a bridge between those language agnostic interfaces and WSGI. This involves calling a flup function with the same WSGI application object above that something like mod_wsgi or Phusion Passenger would use directly without the need for a bridge. For details of this see:

http://trac.saddi.com/flup/wiki/FlupServers

Important thing is to structure your web application so that it is in its own self contained set of modules. To work with a particular server, then create a separate script file as necessary to bridge between what that server requires and your application code. Your application code should always be outside of the web server document directory and only the script file that acts as bridge would be in server document directory if appropriate.

Answer 2

As of July 21 2009, there is a much fuller installation guide at the webpy install site, that discusses flup, fastcgi, apache and more. I haven't yet tried it, but it seems like it's much more detailed.

Answer 3

Here is an example of two hosted apps using cherrypy wsgi server:

#!/usr/bin/python
from web import wsgiserver
import web

# webpy wsgi app
urls = (
  '/test.*', 'index'
)

class index:
    def GET(self):
        web.header("content-type", "text/html")
        return "Hello, world1!"

application = web.application(urls, globals(), autoreload=False).wsgifunc() 


# generic wsgi app
def my_blog_app(environ, start_response):
    status = '200 OK'
    response_headers = [('Content-type','text/plain')]
    start_response(status, response_headers)
    return ['Hello world! - blog\n']


"""
# single hosted app
server = wsgiserver.CherryPyWSGIServer(
            ('0.0.0.0', 8070), application,
            server_name='www.cherrypy.example')

"""

# multiple hosted apps with WSGIPathInfoDispatcher
d = wsgiserver.WSGIPathInfoDispatcher({'/test': application, '/blog': my_blog_app})
server = wsgiserver.CherryPyWSGIServer(('0.0.0.0', 8070), d)            
server.start()