feat(open-webui): HA deployment with CNPG, PDB, and session persistence

- Switch from SQLite/PVC to CNPG PostgreSQL (3 instances, low-resource)
  with a transaction-mode PgBouncer pooler (2 instances)
- Raise open-webui replicas to 3 with priorityClassName: power
- Add PodDisruptionBudget (minAvailable: 1)
- Add Gateway API sessionPersistence (cookie) on the HTTPS HTTPRoute
  so WebSocket connections stick to the same backend pod
- Add postgres-credentials VaultStaticSecret; DATABASE_URL must be
  added to kv/kubernetes/namespace/open-webui/default/open-webui-credentials

apps/base/open-webui/cnpg_cluster.yaml

@@ -0,0 +1,91 @@
+---
+apiVersion: postgresql.cnpg.io/v1
+kind: Cluster
+metadata:
+  name: open-webui-postgres
+  namespace: open-webui
+spec:
+  affinity:
+    podAntiAffinityType: preferred
+  bootstrap:
+    initdb:
+      database: open-webui
+      encoding: UTF8
+      localeCType: C
+      localeCollate: C
+      owner: open-webui
+      secret:
+        name: postgres-credentials
+  enablePDB: true
+  enableSuperuserAccess: false
+  failoverDelay: 0
+  imageName: ghcr.io/cloudnative-pg/postgresql:17-minimal-trixie
+  instances: 3
+  logLevel: info
+  maxSyncReplicas: 0
+  minSyncReplicas: 0
+  monitoring:
+    customQueriesConfigMap:
+      - key: queries
+        name: cnpg-default-monitoring
+    disableDefaultQueries: false
+    enablePodMonitor: false
+  postgresql:
+    parameters:
+      archive_mode: "on"
+      archive_timeout: 5min
+      dynamic_shared_memory_type: posix
+      effective_cache_size: 128MB
+      full_page_writes: "on"
+      log_destination: csvlog
+      log_directory: /controller/log
+      log_filename: postgres
+      log_rotation_age: "0"
+      log_rotation_size: "0"
+      log_truncate_on_rotation: "false"
+      logging_collector: "on"
+      max_connections: "100"
+      max_parallel_workers: "4"
+      max_replication_slots: "16"
+      max_worker_processes: "4"
+      shared_buffers: 64MB
+      shared_memory_type: mmap
+      ssl_max_protocol_version: TLSv1.3
+      ssl_min_protocol_version: TLSv1.3
+      wal_keep_size: 128MB
+      wal_level: logical
+      wal_log_hints: "on"
+      wal_receiver_timeout: 5s
+      wal_sender_timeout: 5s
+    syncReplicaElectionConstraint:
+      enabled: false
+  primaryUpdateMethod: restart
+  primaryUpdateStrategy: unsupervised
+  probes:
+    liveness:
+      isolationCheck:
+        connectionTimeout: 1000
+        enabled: true
+        requestTimeout: 1000
+  replicationSlots:
+    highAvailability:
+      enabled: true
+      slotPrefix: _cnpg_
+    synchronizeReplicas:
+      enabled: true
+    updateInterval: 30
+  resources:
+    limits:
+      cpu: 500m
+      memory: 512Mi
+    requests:
+      cpu: 100m
+      memory: 256Mi
+  smartShutdownTimeout: 180
+  startDelay: 3600
+  stopDelay: 1800
+  storage:
+    resizeInUseVolumes: true
+    size: 5Gi
+    storageClass: cephrbd-fast-delete
+  switchoverDelay: 3600

apps/base/open-webui/cnpg_pooler.yaml

@@ -0,0 +1,33 @@
+---
+apiVersion: postgresql.cnpg.io/v1
+kind: Pooler
+metadata:
+  name: open-webui-postgres-pooler
+  namespace: open-webui
+spec:
+  cluster:
+    name: open-webui-postgres
+  instances: 2
+  pgbouncer:
+    parameters:
+      default_pool_size: "50"
+      max_client_conn: "200"
+    paused: false
+    poolMode: transaction
+  template:
+    metadata:
+      labels:
+        app: pooler
+    spec:
+      affinity:
+        podAntiAffinity:
+          requiredDuringSchedulingIgnoredDuringExecution:
+            - labelSelector:
+                matchExpressions:
+                  - key: app
+                    operator: In
+                    values:
+                      - pooler
+              topologyKey: kubernetes.io/hostname
+      containers: []
+  type: rw

apps/base/open-webui/deployment.yaml

@@ -5,12 +5,10 @@ metadata:
   name: open-webui
   namespace: open-webui
 spec:
-  replicas: 1
+  replicas: 3
   selector:
     matchLabels:
       app: open-webui
-  strategy:
-    type: Recreate
   template:
     metadata:
       annotations:
@@ -18,6 +16,7 @@ spec:
       labels:
         app: open-webui
     spec:
+      priorityClassName: power
       containers:
         - name: open-webui
           image: ghcr.io/open-webui/open-webui:main
@@ -59,11 +58,4 @@ spec:
             requests:
               cpu: 250m
               memory: 512Mi
-          volumeMounts:
-            - mountPath: /app/backend/data
-              name: data
       restartPolicy: Always
-      volumes:
-        - name: data
-          persistentVolumeClaim:
-            claimName: open-webui-data

apps/base/open-webui/httproute.yaml

@@ -47,3 +47,7 @@ spec:
         - path:
             type: PathPrefix
             value: /
+      sessionPersistence:
+        type: Cookie
+        cookieName: open-webui-backend
+        absoluteTimeout: 24h0m0s

apps/base/open-webui/kustomization.yaml

@@ -4,8 +4,10 @@ kind: Kustomization
 
 resources:
   - namespace.yaml
-  - pvc.yaml
+  - cnpg_cluster.yaml
+  - cnpg_pooler.yaml
   - deployment.yaml
+  - pdb.yaml
   - service.yaml
   - gateway.yaml
   - httproute.yaml

apps/base/open-webui/pdb.yaml

@@ -0,0 +1,11 @@
+---
+apiVersion: policy/v1
+kind: PodDisruptionBudget
+metadata:
+  name: open-webui
+  namespace: open-webui
+spec:
+  minAvailable: 1
+  selector:
+    matchLabels:
+      app: open-webui

apps/base/open-webui/pvc.yaml

@@ -1,13 +0,0 @@
----
-apiVersion: v1
-kind: PersistentVolumeClaim
-metadata:
-  name: open-webui-data
-  namespace: open-webui
-spec:
-  accessModes:
-    - ReadWriteOnce
-  resources:
-    requests:
-      storage: 10Gi
-  storageClassName: cephrbd-fast-delete

apps/base/open-webui/vaultstaticsecret.yaml

@@ -1,6 +1,23 @@
 ---
 apiVersion: secrets.hashicorp.com/v1beta1
 kind: VaultStaticSecret
+metadata:
+  name: postgres-credentials
+  namespace: open-webui
+spec:
+  destination:
+    create: true
+    name: postgres-credentials
+    overwrite: true
+  hmacSecretData: true
+  mount: kv
+  path: kubernetes/namespace/open-webui/default/postgres-credentials
+  refreshAfter: 5m
+  type: kv-v2
+  vaultAuthRef: default
+---
+apiVersion: secrets.hashicorp.com/v1beta1
+kind: VaultStaticSecret
 metadata:
   name: open-webui-credentials
   namespace: open-webui