Add an example for the gunicorn.app.base.BaseApplication

docs/source/run.rst

@@ -127,3 +127,60 @@ However, in this configuration, Gunicorn does not reload the application when
 new workers are started. See the note about preloading_.
 
 .. _preloading: configure.html#preload-app
+
+
+custom application
+------------------
+
+Sometimes, you want to integrate Gunicorn with your WSGI application. In this
+case, you can inherit from gunicorn.app.base.BaseApplication.
+
+Example::
+
+    #!/usr/bin/env python
+    import gunicorn.app.base
+
+    def my_index(environ, start_response):
+        response_body = 'Works fine'
+        status = '200 OK'
+
+        response_headers = [
+            ('Content-Type', 'text/plain'),
+            ('Content-Length', str(len(response_body)))
+        ]
+
+        start_response(status, response_headers)
+
+        return [response_body]
+
+    class MyApplication(gunicorn.app.base.BaseApplication):
+        def __init__(self, app, options=None):
+            self.options = dict(options or {})
+            self.application = app
+            super(MyApplication, self).__init__()
+
+        def load_config(self):
+            tmp_config = map(
+                lambda item: (item[0].lower(), item[1]),
+                self.options.iteritems()
+            )
+
+            config = dict(
+                (key, value)
+                for key, value in tmp_config
+                if key in self.cfg.settings and value is not None
+            )
+
+            for key, value in config.iteritems():
+                self.cfg.set(key.lower(), value)
+
+        def load(self):
+            return self.application
+
+    if __name__ == '__main__':
+        options = {
+            'bind': '%s:%s' % ('127.0.0.1', '8080'),
+            'workers': 4,
+            # 'pidfile': pidfile,
+        }
+        MyApplication(my_index, options).run()