ALERT K8SControllerManagerDown
  IF absent(up{job="kube-controller-manager"}) or (count by(cluster) (up{job="kube-controller-manager"} == 1) == 0)
  FOR 5m
  LABELS {
    severity = "critical",
  }
  ANNOTATIONS {
    summary = "Controller manager is down",
    description = "There is no running K8S controller manager. Deployments and replication controllers are not making progress.",
  }