AD usernames can have a "." (dot) in them i.e. they can be of the format -> firstname.lastname. However, if you specify a username with this format against the Capacity Scheduler setting -> yarn.scheduler.capacity.root.default.user-settings.firstname.lastname.weight, it fails to be applied and is instead assigned the default of 1.0f weight. This renders the user weight feature (being used as a means of setting user priorities for a queue) unusable for such users.
This limitation comes from . From , only word characters (A word character: [a-zA-Z_0-9]) (see ) are permissible at the moment which is no good for AD names that contain a "." (dot).
We could go down similar path and unblock this feature for the AD usernames with a "." (dot) in them.