title: Prometheus alerts first counter value
body: <p>I'm trying to create an alert for errors. There is a metric which counts errors occurred in an application. But when I try to catch its increase it always returns 0.</p>
  <pre><code>increase(app_error[1h])
  </code></pre>
  <p>Even if I do it with an offset <code>offset 5h</code>, to the point when it was encountered first, it just disappears. Is there a way to find that first error encounter and its first value increasing(from 0 to 1)? I need to fire the alert only on the first count of that metric.</p>