add infra app prometheus-altertmanager

kubernetes/infrastructure/prometheus-alertmanager/prometheus-alertmanager.yaml

@@ -0,0 +1,18 @@
+apiVersion: kustomize.toolkit.fluxcd.io/v1
+kind: Kustomization
+metadata:
+  name: prometheus-alertmanager
+  namespace: prometheus
+spec:
+  interval: 10m
+  timeout: 1m30s
+  retryInterval: 30s
+  path: ./kubernetes/infrastructure/prometheus-alertmanager/app
+  prune: true
+  sourceRef:
+    kind: GitRepository
+    namespace: flux-system
+    name: flux-system
+  dependsOn:
+    - name: namespaces
+      namespace: flux-system