- -

-

Other Servers¶

-

There are popular servers written in Python that allow the execution of WSGI -applications as well. These servers stand alone when they run; you can proxy -to them from your web server.

-

Tornado¶

-

Tornado is an open source version of the scalable, non-blocking web -server and tools that power FriendFeed. Because it is non-blocking and -uses epoll, it can handle thousands of simultaneous standing connections, -which means it is ideal for real-time web services. Integrating this -service with Flask is a trivial task:

-

from tornado.wsgi import WSGIContainer
-from tornado.httpserver import HTTPServer
-from tornado.ioloop import IOLoop
-from yourapplication import app
-
-http_server = HTTPServer(WSGIContainer(app))
-http_server.listen(5000)
-IOLoop.instance().start()
-

-

-

Gevent¶

-

Gevent is a coroutine-based Python networking library that uses -greenlet to provide a high-level synchronous API on top of libevent -event loop:

-

from gevent.wsgi import WSGIServer
-from yourapplication import app
-
-http_server = WSGIServer(('', 5000), app)
-http_server.serve_forever()
-

-

-

Gunicorn¶

-

Gunicorn ‘Green Unicorn’ is a WSGI HTTP Server for UNIX. It’s a pre-fork -worker model ported from Ruby’s Unicorn project. It supports both eventlet -and greenlet. Running a Flask application on this server is quite simple:

-

gunicorn myproject:app

-

Gunicorn provides many command-line options – see gunicorn -h. -For example, to run a Flask application with 4 worker processes (-w -4) binding to localhost port 4000 (-b 127.0.0.1:4000):

-

gunicorn -w 4 -b 127.0.0.1:4000 myproject:app

-

Proxy Setups¶

-

If you deploy your application using one of these servers behind an HTTP -proxy you will need to rewrite a few headers in order for the -application to work. The two problematic values in the WSGI environment -usually are REMOTE_ADDR and HTTP_HOST. Werkzeug ships a fixer that -will solve some common setups, but you might want to write your own WSGI -middleware for specific setups.

-

The most common setup invokes the host being set from X-Forwarded-Host -and the remote address from X-Forwarded-For:

-

from werkzeug.contrib.fixers import ProxyFix
-app.wsgi_app = ProxyFix(app.wsgi_app)
-

-

-

Please keep in mind that it is a security issue to use such a middleware -in a non-proxy setup because it will blindly trust the incoming -headers which might be forged by malicious clients.

-

If you want to rewrite the headers from another header, you might want to -use a fixer like this:

-

class CustomProxyFix(object):
-
-    def __init__(self, app):
-        self.app = app
-
-    def __call__(self, environ, start_response):
-        host = environ.get('HTTP_X_FHOST', '')
-        if host:
-            environ['HTTP_HOST'] = host
-        return self.app(environ, start_response)
-
-app.wsgi_app = CustomProxyFix(app.wsgi_app)
-

-

-

- - -

Other Servers¶

Tornado¶

Gevent¶

Gunicorn¶

Proxy Setups¶

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Other Servers¶

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Gunicorn¶

Proxy Setups¶

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