title: How can I filter the result of label_values(label) to get a list of labels that match a regex?
body: <p>I have several metrics with the label "service". I want to get a list of all the "service" levels that begin with "abc" and end with "xyz". These will be the values of a grafana template variable.</p>
  
  <p>This is that I have tried:
  <code>label_values(service) =~ "abc.*xyz"</code></p>
  
  <p>However this produces a error <code>Template variables could not be initialized: parse error at char 13: could not parse remaining input "(service_name) "...</code></p>
  
  <p>Any ideas on how to filter the label values?</p>