How is it possible to use variables in director notifications?

Hey all,

i just read the Monitoring Basics - Icinga 2 and wondered how its possible to do that with the director? Currently i have the usecase to set users, usergroups and time period in the notification apply rule to variables and cant find a possiblity to do this in director. How can i achive that functionality? Im trying to reduce the many rules i currently have and want to be more flexible.

Thanks in advance and greetings