Werkzeug DebuggedApplication with uWSGI under lighttpd.

uWSGI is a fairly awesome app server; it's lightweight and fast, yet highly stable.

Unfortunately, mod_uwsgi for lighttpd is somewhat half-baked. Aside from yet another app server using the equivalent of urllib.unquote instead of urllib.unquote_plus, it also behaves differently than most app servers in dealing with query parameters.

This led to headaches when trying to use Werkzeug's awesome Ajax-based python interpreter-in-a-page, as the static asset requests were not getting caught by Werkzeug's middleware. If you watch it with firebug, you'll see 404's for a bunch of requests:

__debugger__/?cmd=resource&f=style.css
__debugger__/?cmd=resource&f=jquery.js
__debugger__/?cmd=resource&f=debugger.js
__debugger__/?cmd=resource&f=console.png
__debugger__/?cmd=resource&f=source.png

What's the fix? Rewrite some of the environ coming from uWSGI, using a middleware in your wsgi handler module:

if condition_to_enable_werkzeug:
   try:
       from werkzeug.debug import DebuggedApplication

       class WerkzeugDebugger(DebuggedApplication):

           def __call__(self, environ, start_response):
               #fix uwsig's environ
               environ['QUERY_STRING'] = environ['QUERY_STRING'].split('?')[0]
               environ['REQUEST_URI'] = environ['REQUEST_URI'].split('?')[0]
               environ['PATH_INFO'] = environ['PATH_INFO'].split('?')[0]
               return super(WerkzeugDebugger, self).__call__(environ, start_response)

       #wrap this middleware around the your application
       application = WerkzeugDebugger(application, evalex=True)
       application.werkzeug = True #or whatever, if you need to disable your own error handler
   except ImportError, e: #werkzeug not found
       pass