groups:
  - name: host.rules
    rules:
      - alert: HostExporterDown
        expr: up{job="node-exporter"} == 0
        for: 2m
        labels:
          severity: critical
        annotations:
          summary: "Node exporter is unavailable"
          description: "Prometheus has failed to scrape {{ $labels.instance }} for more than two minutes."

      - alert: HostHighCPU
        expr: 100 - (avg by(instance) (rate(node_cpu_seconds_total{mode="idle"}[5m])) * 100) > 85
        for: 10m
        labels:
          severity: warning
        annotations:
          summary: "High CPU utilization"
          description: "CPU utilization on {{ $labels.instance }} has exceeded 85% for ten minutes."