The template user
A template user can be any user and is not specifically marked as a template user. As Cacti does not include group management, template users should be created as templates for different users. As you have just learned, graph and realm permissions need to be set for a user to only view graphs for Customer A. If you are now going to have multiple customers, you do not want to start from scratch every time. This is where a template user becomes handy.
In a multi-customer environment the template user should follow an easy to understand naming standard and should always be disabled.
Tip
Use a naming standard for template users
An example for such a naming standard would be _customername_user.
