Replace beaker sessions with itsdangerous based sessions

[Elrond]

We want to switch from beaker sessions to itsdangerous based sessions.
Why? We should come up with a better list of reaasons than "The core developers like this idea".

What's needed?

1. Remove beaker sessions from paste*.ini
2. Create a class that will be our new request.session
3. Create code to create such an instance from a received cookie.
4. Create code to send a (modified) session as a cookie to the client.

Some more Details

Create a class that will be our new request.session

Some pseudo code:

class MGSession(dict):

    def save(self):
        self.send_new_cookie = True

    def delete(self):
        self.clear()
        self.save()

Create Session Instance from cookie

Here's some pseudo code to do that. It includes code for future "revocation support". Because we do not store anything locally any more, one can only forcibly block sessions by blacklisting. In the first step, its okay to document the needed approach in the code.

class SessionManager(object):
    def load_session_from_cookie(request, cookie_name):
        cookie = request.get_cookie(cookie_name)
        if not cookie:
            request.session = MGSession()
            return
        m = BadCookie.query.filter_by(cookie = cookie)
        if m:
            _log.warn("Bad cookie received: %s", m.reason)
            raise BadRequest()
        parsed_dict = self.signer.loads(cookie, max_age=...)
        requestion.session = MGSession(parsed_dict)

Send cookie

• Only send a cookie, if an update is needed
• If the session is empty delete the cookie on the client (MGSession.delete() was called probably)
• Bonus points: Consider sending a new cookie, if the old one is going to expire soon

[Elrond]

From #580:
This might be helpful too: ​http://flask.pocoo.org/snippets/51/

[Elrond]

some small changes to example pseudo code, mostly suggesting a SessionManager class.

[Elrond]

Small update: bcs / brett is working on this. I'm mostly waiting for a ping to merge his branch.

[Christopher Allan Webber]

Brett, any updates on this? It sounds like it's close, and I'd really love to see it land!

[Elrond]

This has been merged!

I am claiming the ticket to clean up the last bits.

[Christopher Allan Webber]

Hey Elrond,

Is there anything that's still being cleaned up or can we close this?

[Elrond]

Really, I have no idea.

It's probably done, I'm guessing.

If there's something wrong, we'll file a new bug.

[Christopher Allan Webber]

This landed a long time ago. I think Elrond at one point wanted to do cleanup, but whatever was wanted either has been done or the memory of what that cleanup was has been lost to the sands of time. Regardless, things seem to be working fine now. Closed!