gistfile1.py

class ReverseProxied(object):
    def __init__(self, app):
        self.app = app

    def __call__(self, environ, start_response):
        script_name = environ.get('HTTP_X_SCRIPT_NAME', None)
        if script_name is not None:
            environ['SCRIPT_NAME'] = script_name
            path_info = environ['PATH_INFO']
            if path_info.startswith(script_name):
                path_info = path_info[len(script_name):]
                environ['PATH_INFO'] = path_info

        scheme = environ.get('HTTP_X_SCHEME', None)
        if scheme is not None:
            environ['wsgi_url_scheme'] = scheme
        return self.app(environ, start_response)


app = Flask(__name__)
app.wsgi_app = ReverseProxied(app.wsgi_app)