How to run twisted with flask?

You can use the WSGIResource from Twisted istead of a ReverseProxy.

UPDATE: Added a more complex example that sets up a WSGIResource at /my_flask and a ReverseProxy at /example

from flask import Flask
from twisted.internet import reactor
from twisted.web.proxy import ReverseProxyResource
from twisted.web.resource import Resource
from twisted.web.server import Site
from twisted.web.wsgi import WSGIResource

app = Flask(__name__)


@app.route('/example')
def index():
    return 'My Twisted Flask'

flask_site = WSGIResource(reactor, reactor.getThreadPool(), app)

root = Resource()
root.putChild('my_flask', flask_site)

site_example = ReverseProxyResource('www.example.com', 80, '/')
root.putChild('example', site_example)


reactor.listenTCP(8081, Site(root))
reactor.run()

Try running the above in your localhost and then visiting localhost:8081/my_flask/example or localhost:8081/example


You should give klein a try. It's made and used by most of the twisted core devs. The syntax is very much like flask so you won't have to rewrite much if you already have a working flask app. So something like the following should work:

from twisted.internet import reactor
from twisted.web import proxy, server
from klein import Klein

app = Klein()

@app.route('/example')
def home(request):
    site = server.Site(proxy.ReverseProxyResource('www.example.com', 80, ''.encode("utf-8")))
    reactor.listenTCP(80, site)

app.run('localhost', 8000)        # start the klein app on port 8000 and reactor event loop

Links

  • Klein Docs
  • Klein Github

The accepted answer does not cover how to run twisted with Flask, and points to a different framework. The answer with an example no longer works either.

Here are two different examples. The first one is the same as the first answer, but fixed to work on Python 3

from flask import Flask
from twisted.internet import reactor
from twisted.web.proxy import ReverseProxyResource
from twisted.web.resource import Resource
from twisted.web.server import Site
from twisted.web.wsgi import WSGIResource

app = Flask(__name__)


@app.route('/example')
def index():
    return 'My Twisted Flask'

flask_site = WSGIResource(reactor, reactor.getThreadPool(), app)

root = Resource()
root.putChild(b'my_flask', flask_site)

site_example = ReverseProxyResource('www.example.com', 80, b'/')
root.putChild(b'example', site_example)


reactor.listenTCP(8081, Site(root))
reactor.run()

For this example, run it and open any of these:

localhost:8081/my_flask/example

localhost:8081/example

This other example is recommended, since it sets up two services and provides them through a .tac file to twistd. Take the base code from here: https://github.com/pika/pika/blob/master/examples/twisted_service.py

"""Modify the bottom of the file to pick the new MultiService"""
# ... all the code from twisted_service.py goes here.
# Scroll to the bottom of the file and
# remove everything below application = service.Application("pikaapplication")
# You should keep the PikaService, PikaProtocol and PikaFactory
# classes, since we need them for this code:
from pika.connection import ConnectionParameters
from pika.credentials import PlainCredentials
from twisted.application import service, strports
from twisted.internet import reactor
from twisted.web.server import Site
from twisted.web.wsgi import WSGIResource
from flask import Flask

# This IServiceCollection will hold Pika and Flask
flask_pika_multiservice = service.MultiService()

# FLASK SERVICE SETUP
app = Flask("demoapp")
@app.route('/')
def hello_world():
    return 'Hello, World!'

flask_site = Site(WSGIResource(reactor, reactor.getThreadPool(), app))

# New resources can be added, such as WSGI, or proxies by creating
# a root resource in the place of the flask_site, and adding the
# new resources to the root.
# root = Resource()
# root.putChild(b'my_flask_site', flask_site)
# from twisted.web.proxy import ReverseProxyResource
# site_example = ReverseProxyResource('www.example.com', 80, b'/')
# root.putChild(b'example', site_example)

i = strports.service(f"tcp:8088", flask_site)
i.setServiceParent(flask_pika_multiservice)

# PIKA SERVICE SETUP
ps = PikaService(
    ConnectionParameters(
        host="localhost",
        virtual_host="/",
        credentials=PlainCredentials("guest", "guest")))
ps.setServiceParent(flask_pika_multiservice)

# Application setup
application = service.Application('flask_pika')
flask_pika_multiservice.setServiceParent(application)

Now you can run it with:

PYTHONPATH=. twistd -ny twisted_service.py

you can skip the python path if you don't want to import anything from the same path. twisted expects projects to actually be installed, and does not support running them directly from the source folder unless you use that workaround.

This second example establishes two services, on different ports. It's for pika and flask running simultaneously on the same twisted server. The best part is that it shows how to set up flask as a service, that can be part of an IServiceCollection

Tags:

Python

Reverse Proxy

Twisted

Flask

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