feat: add nginx-ingress ServiceMonitor for gateway traffic metrics

k8s/infra/monitoring/kustomization.yaml

@@ -18,5 +18,6 @@ resources:
   - servicemonitors/authentik.yaml
   - servicemonitors/forgejo.yaml
   - servicemonitors/minio.yaml
+  - servicemonitors/ingress-nginx.yaml
   - dashboards/cluster-infrastructure.yaml
   - dashboards/api-gateway.yaml

k8s/infra/monitoring/servicemonitors/ingress-nginx.yaml

@@ -0,0 +1,18 @@
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: ingress-nginx
+  namespace: monitoring
+  labels:
+    release: prometheus
+spec:
+  namespaceSelector:
+    matchNames:
+      - ingress-nginx
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: ingress-nginx
+      app.kubernetes.io/component: controller
+  endpoints:
+    - port: metrics
+      interval: 30s