Add authentication docs

docs/authentication.rst

@@ -0,0 +1,15 @@
+.. _authentication:
+
+=========================
+Setting up Authentication
+=========================
+
+Locust uses `Flask-Login <https://pypi.org/project/Flask-Login/>`_ to handle authentication. The ``login_manager`` is exposed on ``environment.web_ui.app``, allowing the flexibility for you to implement any kind of auth that you would like!
+
+To use username / password authentication, simply provide a ``usernamePasswordCallback`` to the ``environment.web_ui.auth_args``. You are responsible for defining the route for the callback and implementing the authentication.
+
+Authentication providers can additionally be configured to allow authentication from 3rd parties such as GitHub or an SSO. Simply provider a list of desired ``auth_providers``. You may specify the ``label`` and ``icon`` for display on the button. The ``callback_url`` will be the url that the button directs to. You will be responsible for defining the callback route as well as the authentication with the 3rd party.
+
+Whether you are using username / password authentication, an auth provider, or both, a ``user_loader`` needs to be proivded to the ``login_manager``. The ``user_loader`` should return ``None`` to deny authentication and return a User object when authentication to the app should be granted.
+
+A full example can be seen `in the auth example <https://github.com/locustio/locust/tree/master/examples/auth.py>`_.

docs/index.rst

@@ -58,6 +58,7 @@ Other functionalities
     extending-locust
     logging
     use-as-lib
+    authentication
 
 
 Further reading / knowledgebase