You're right, it does use that. The security against untrusted users is whatever you get from docker - each user's code runs in an individual container. In the

You're right, it does use that. The security against untrusted users is whatever you get from docker - each user's code runs in an individual container. In the case of try.jupyter.org a breakout would not be catastrophic, though, because those servers shouldn't be holding any sensitive data.