aula-12: Victoria Metrics + Grafana via GitOps

Stack completo de observabilidade:
- Victoria Metrics (vmsingle, vmagent, vmalert)
- Grafana com dashboards built-in
- Alertas customizados (PVC, pods, nodes, deployments)
- pvc-autoresizer para expansão automática de volumes
- Queries PromQL documentadas

Instalação via ArgoCD seguindo padrão GitOps da aula-11.

aula-12/alerts/vmalert-rules.yaml

@@ -0,0 +1,100 @@
+# =============================================================================
+# VMRule - Regras de Alerta (Referência)
+# =============================================================================
+#
+# Este arquivo é apenas referência. A versão aplicada está em:
+#   gitops/apps/victoria-metrics/templates/alerts.yaml
+#
+# Para aplicar manualmente (sem GitOps):
+#   kubectl apply -f alerts/vmalert-rules.yaml -n monitoring
+#
+# =============================================================================
+
+apiVersion: operator.victoriametrics.com/v1beta1
+kind: VMRule
+metadata:
+  name: custom-alerts
+  namespace: monitoring
+spec:
+  groups:
+    # -------------------------------------------------------------------------
+    # Alertas de Storage/PVC
+    # -------------------------------------------------------------------------
+    - name: storage-alerts
+      rules:
+        - alert: PVCAlmostFull
+          expr: |
+            (kubelet_volume_stats_used_bytes / kubelet_volume_stats_capacity_bytes) > 0.8
+            and
+            (kubelet_volume_stats_used_bytes / kubelet_volume_stats_capacity_bytes) < 0.95
+          for: 5m
+          labels:
+            severity: warning
+          annotations:
+            summary: "PVC {{ $labels.persistentvolumeclaim }} está acima de 80%"
+            description: "PVC {{ $labels.persistentvolumeclaim }} no namespace {{ $labels.namespace }} está usando {{ $value | humanizePercentage }} do espaço."
+
+        - alert: PVCFull
+          expr: |
+            (kubelet_volume_stats_used_bytes / kubelet_volume_stats_capacity_bytes) > 0.95
+          for: 1m
+          labels:
+            severity: critical
+          annotations:
+            summary: "PVC {{ $labels.persistentvolumeclaim }} está CHEIO (>95%)"
+            description: "AÇÃO URGENTE NECESSÁRIA!"
+
+    # -------------------------------------------------------------------------
+    # Alertas de Pods
+    # -------------------------------------------------------------------------
+    - name: pod-alerts
+      rules:
+        - alert: PodCrashLooping
+          expr: |
+            sum(increase(kube_pod_container_status_restarts_total[1h])) by (pod, namespace) > 5
+          for: 5m
+          labels:
+            severity: warning
+          annotations:
+            summary: "Pod {{ $labels.pod }} está em CrashLoop"
+
+        - alert: PodNotReady
+          expr: |
+            kube_pod_status_ready{condition="false"} == 1
+          for: 5m
+          labels:
+            severity: warning
+          annotations:
+            summary: "Pod {{ $labels.pod }} não está Ready"
+
+    # -------------------------------------------------------------------------
+    # Alertas de Nodes
+    # -------------------------------------------------------------------------
+    - name: node-alerts
+      rules:
+        - alert: NodeHighCPU
+          expr: |
+            100 - (avg by(instance) (rate(node_cpu_seconds_total{mode="idle"}[5m])) * 100) > 90
+          for: 5m
+          labels:
+            severity: warning
+          annotations:
+            summary: "Node {{ $labels.instance }} com CPU alta"
+
+        - alert: NodeLowMemory
+          expr: |
+            (node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes) < 0.1
+          for: 5m
+          labels:
+            severity: warning
+          annotations:
+            summary: "Node {{ $labels.instance }} com pouca memória"
+
+        - alert: NodeDiskFull
+          expr: |
+            (node_filesystem_avail_bytes{fstype!~"tmpfs|overlay"} / node_filesystem_size_bytes{fstype!~"tmpfs|overlay"}) < 0.15
+          for: 5m
+          labels:
+            severity: critical
+          annotations:
+            summary: "Disco do Node {{ $labels.instance }} quase cheio"