title: Terraform - NAT Exhaustion alerting policy - what's the metric?
body: <p>I'm having trouble understanding the 'metrics' used in GCP's alerting policies, and how to use them with terraform.</p>
  <p>I'm trying to create an alerting policy, for when we see the NAT Exhaustion errors.</p>
  <p>Currently I have this:</p>
  <pre><code>+ filter          = &quot;metric.type=\&quot;router.googleapis.com/nat/nat_allocation_failed\&quot; resource.type=\&quot;nat_gateway\&quot; metric.label.\&quot;gateway_name\&quot;=\&quot;xx-dmz-region1-nat-gw\&quot; resource.label.\&quot;project_id\&quot;=\&quot;devops-xx-sandbox-xxx\&quot;&quot;
  </code></pre>
  <p>However, terraform tells me the metric is invalid, and to select a correct metric. How do I find a list of the metrics and choose the right one? I got these details from the query editor, by looking at an existing query in the GCP console</p>