cluster-service/alerts/testing-prometheusRule.yaml

apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  labels:
    app.kubernetes.io/name: kube-prometheus
    app.kubernetes.io/part-of: kube-prometheus
    prometheus: k8s
    role: alert-rules
  name: kubernetes-monitoring-rules
  namespace: monitoring
spec:
  groups:
  - name: InstancesDownV1
    rules:
    - alert: InstancesDownV1
      expr: sum(up{job="app"}) == 0
      labels:
        severity: critical
      annotations:
        summary: "All instances of the App are down"
        description: "All instances of the App are down"