WebOb middleware to force ssl on Heroku

runapp.py

import os

from webob.dec import wsgify
from webob.exc import HTTPMovedPermanently

from paste.deploy import loadapp
from waitress import serve

@wsgify.middleware
def ForceSSLMiddleware(req, app):
    # check that the incoming request was using https
    if req.headers['X-Forwarded-Proto'] != 'https':
        https_url = req.url.replace('http://', 'https://')
        return HTTPMovedPermanently(location=https_url)

    # override the request scheme to tell the app that we are using https
    req.scheme = 'https'

    resp = req.get_response(app)
    return resp

if __name__ == "__main__":
    port = int(os.environ.get("PORT", 5000))
    app = loadapp('config:production.ini', relative_to='.')
    app = ForceSSLMiddleware(app)

    serve(app, host='0.0.0.0', port=port)