Observabilidade 3 — Alertas e Alertmanager

1. Regra de alerta

groups:
  - name: hosts
    rules:
      - alert: InstanceDown
        expr: up == 0
        for: 2m
        labels: {severity: critical}
        annotations:
          summary: "Instância {{ $labels.instance }} down"
      - alert: HighCPU
        expr: 100 - (avg by(instance) (rate(node_cpu_seconds_total{mode="idle"}[5m])) * 100) > 90
        for: 5m
        labels: {severity: warning}

2. Alertmanager (resumo)

route:
  receiver: default
receivers:
  - name: default
    email_configs:
      - to: [email protected]
        from: [email protected]
        smarthost: smtp.exemplo.com:587

Ou use webhook para Telegram/Slack/Discord.