title: PromQL. How to add label value from different metric
body: <p>If I have two metrics:</p>
  
  <pre><code>kube_pod_container_status_restarts_total {..., pod="my_pod_name_42", ...}
  </code></pre>
  
  <p>and</p>
  
  <pre><code>container_memory_usage_bytes {..., pod_name="my_pod_name_42", cluster_name="megatron", ...}
  </code></pre>
  
  <p>And I want to set up alert for restart metrics, but containing <code>cluster_name</code> label. 
  Can I somehow aggregate label value from different metrics.</p>
  
  <p>For example alert: </p>
  
  <pre><code>increase(kube_pod_container_status_restarts_total{namespace="42"}[1h])&gt;4    
  </code></pre>
  
  <p>need to somehow add <code>megatron</code> here ^, for alertmanager to be able to use this label when sending notification</p>