title: Grafana - use custom variable as regex in query
body: <p>we have prometheus datasource and I’m stuck at trying to use custom variable with few values as comma separated values, I wanted to use it to replace as regex in the label_values(job=~$"{eks_cluster:regex}"), but i get the error templating variables could not be initialized.
  Following are the screenshots to show what I’m trying to achieve
  <a href="https://i.stack.imgur.com/9nMNo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9nMNo.png" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/xtijf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xtijf.png" alt="enter image description here"></a></p>