A flask with a web server terminates all sessions?

Question

For example, this code:

from flask import session @app.route('/is_logged_in/') def is_logged_in(): return 'user' in session 

It works fine for me when starting the Flask development server, but it gives a 500 error with any web server setup (FastCGI, uWSGI, etc.) on any server (Apache, nginx, Lighttpd).

Does anyone know why?

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My actual code is on GitHub, if that matters.

It works flawlessly when working with the internal Flask server, but I cannot get the session variables to work with the production web server: https://github.com/Blender3D/Webminal/blob/master/server.py

Answer 1

I finally tried Tornado , thinking it would help with my problems (this is written in Python, after all).

Lo and behold, readable trace:

 RuntimeError: the session is unavailable because no secret key was set. Set the secret_key on the application to something unique and secret. 

Looks like I just forgot to add a secret key for signing up sessions with:

 app.secret_key = 'why would I tell you my secret key?' 

Answer 2

Your return value must be one of several types: a basestring ( string or unicode ), a tuple (representing the arguments passed to the constructor of the Response object), a Response object itself, or - rejection of them - a function that calls WSGI.

You return the bool . Flask suggests that since it is not a basestring , tuple or Response object, it must be WSGI-invoked. Subsequently, when processing the response, it tries to call () your return value bool , which leads to an exception. The flag captures the received TypeError. When Flask is in debug mode, it passes this back to a simple Werkzeug web server, which will call the built-in debugger. However, when Flask is in production mode, it will simply cause an internal server error - for example, code 500 - without additional information.

So, to fix your problem, make sure you do this:

return str('user' in session)

Answer 3

Although, in fact, this does not answer your question, I would rewrite it like this:

 from flask import redirect, session, url_for @app.route('/') def index(): return 'foo' @app.route('/is_logged_in/') def is_logged_in(): user = session.get('user', None) if user: return user return redirect(url_for('index'))