Alert with dynamic host on a dashboard

I made a dashboard with many panels, the data change once I change the choice of my host from my dropdown list build from a variable.

Everything is fine but now, when I set an alert :

I see that error message

"/!\ Template variables are not supported in alert queries "

How can I do ?

Is it mandatory to create one dashboard per host to be able to get alert ?

it looks like it’s not for tomorrow