# VMRule - Alertas de Latência e Erros (APM)
# Baseado em métricas geradas pelo spanmetrics connector do OpenTelemetry Collector
# Métrica: http_server_request_duration_seconds_bucket

apiVersion: operator.victoriametrics.com/v1beta1
kind: VMRule
metadata:
  name: latency-alerts
  namespace: monitoring
  labels:
    app: victoria-metrics
spec:
  groups:
    - name: apm.latency
      rules:
        # Doherty Threshold: resposta acima de 400ms degrada a produtividade do usuário
        - alert: DohertyThresholdExceeded
          expr: |
            histogram_quantile(0.95,
              sum(rate(http_server_request_duration_seconds_bucket[5m])) by (le, service)
            ) > 0.4
          for: 5m
          labels:
            severity: warning
          annotations:
            summary: "P95 latency above Doherty threshold (400ms) for {{ $labels.service }}"
            description: "Service {{ $labels.service }} has P95 latency of {{ $value | humanizeDuration }}. The Doherty threshold (400ms) states that productivity degrades when response time exceeds this limit."

        # Taxa de erros HTTP 5xx acima de 1%
        - alert: HighErrorRate
          expr: |
            (
              sum(rate(http_server_request_duration_seconds_count{http_status_code=~"5.."}[5m])) by (service)
              /
              sum(rate(http_server_request_duration_seconds_count[5m])) by (service)
            ) > 0.01
          for: 5m
          labels:
            severity: warning
          annotations:
            summary: "Error rate above 1% for {{ $labels.service }}"
            description: "Service {{ $labels.service }} has {{ $value | humanizePercentage }} error rate (5xx responses)."

        # P99 acima de 1 segundo - latência crítica
        - alert: HighRequestLatencyP99
          expr: |
            histogram_quantile(0.99,
              sum(rate(http_server_request_duration_seconds_bucket[5m])) by (le, service)
            ) > 1
          for: 5m
          labels:
            severity: critical
          annotations:
            summary: "P99 latency above 1s for {{ $labels.service }}"
            description: "Service {{ $labels.service }} has P99 latency of {{ $value | humanizeDuration }}. This indicates severe performance degradation."