Flask url_for generating http URL instead of https

Question

I am using url_for to generate a redirect URL when a user has logged out:

return redirect(url_for(\'.index\', _external=True))

Answer 1

Setting _scheme on every url_for() call is extremely tedious, and PREFERRED_URL_SCHEME doesn't seem to work. However, mucking with what the request's supposed scheme is at the WSGI level seems to successfully convince Flask to always construct HTTPS URLs:

def _force_https(app):
    def wrapper(environ, start_response):
        environ['wsgi.url_scheme'] = 'https'
        return app(environ, start_response)
    return wrapper

app = Flask(...)

app = _force_https(app)