Grafana Promql tamplates

I have panel query for cpu utilization as given
cpu_utilization{host=~"$hostname", env=~“prod”}

I am getting values for hostnames from variables. But if variable is none , then my above query starts showing stats for all servers in dev, uat and prod . How to handle this ?

Please share any suggestion .

Thanks

Hi @sunilsagar

What version of grafana are you using? prometheus version?