apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: cluster-node-alerts
  labels:
    app: kube-prometheus-stack
    app.kubernetes.io/instance: {{ .Release.Name }}
spec:
  groups:
  - name: node.alerts
    rules:
    - alert: NodeHighCPU
      expr: (1 - avg by (instance) (rate(node_cpu_seconds_total{mode="idle"}[5m]))) * 100 > 20
      for: 2m
      labels:
        severity: warning
      annotations:
        summary: "High CPU usage on node {{ "{{" }} $labels.instance {{ "}}" }}"
        description: "Node {{ "{{" }} $labels.instance {{ "}}" }} has CPU usage above 20% (current value: {{ "{{" }} $value | printf \"%.2f\" {{ "}}" }}%)"