Prometheus 指标与告警：Alertmanager 最小配置

global:
  scrape_interval: 15s
scrape_configs:
  - job_name: node
    static_configs:
      - targets: ['localhost:9100']
rule_files:
  - alerts.yml

groups:
- name: basic
  rules:
  - alert: InstanceDown
    expr: up == 0
    for: 1m
    labels: { severity: critical }
    annotations:
      summary: "Instance down"
      description: "{{ $labels.instance }} is down"

route:
  receiver: 'webhook'
receivers:
- name: 'webhook'
  webhook_configs:
  - url: 'http://localhost:8080/alert'