告警规则

告警规则文件的格式如下：

groups:
- name: example        # 尚不清楚是否需要与alertmanager.yml中的route.groupby的名字保持一致
  rules:
  - alert: NodeMemoryUsage
    expr: (node_memory_MemTotal_bytes - node_memory_MemAvailable_bytes) / node_memory_MemTotal_bytes * 100 > 20
    for: 1m
    annotations:
      summary: "{{$labels.instance}}: High Memory usage detected"
      description: "{{$labels.instance}}: Memory usage is above 20% (current value is:{{ $value }})"

Reference

【1】https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/