Buildbot: how to require authentication for all users?

Question

By default, the Buildbot web interface grants unlimited access to all functionality for anonymous users. With the use of authentication plugins (e.g. buildbot.www.auth.UserPasswordAuth), anonymous users can be reduced to read-only access. Is there a way to take this one step further by disallowing access for anonymous users altogether? i.e. Is there a way to require a user to be logged in before they can see anything?

Buildbot version: 2.3.1

I found an old question (How to enable basic access authentication with Buildbot) that appears to have a solution, but it is only for very old versions of Buildbot.