title: Grafana variable and Prometheus query
body: <p>I have a problem trying to create a custom variable of type <code>query</code> with this formula :</p>
  
  <pre><code>label_values(increase(nginx_ingress_controller_requests{namespace=~"$Namespace"}[10m])&gt;0,ingress)
  </code></pre>
  
  <p>When I play this query against the prometheus server (without "label_values" which is a grafan templating function) it works fine.</p>
  
  <p>I have the following toast error :</p>
  
  <pre><code>Template variables could not be initialized: parse error at char 9: could not parse remaining input "(nginx_ingress_"...
  </code></pre>
  
  <p>The aim of this variable is to list only Ingress labels that had an activity during the last 10m.</p>