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为Kubernetes StatefulSet恢复一个卷

Longhorn 支持恢复备份，其中一个使用场景是为 Kubernetes StatefulSet 恢复数据，这需要为每个被备份的副本恢复一个卷。

要恢复，请按照以下说明操作。下面的示例使用一个 StatefulSet，每个 Pod 附加一个卷，并有两个副本。

在您的网页浏览器中连接到`Longhorn UI`页面。在`Backup`选项卡下，选择StatefulSet卷的名称。点击卷条目的下拉菜单并恢复它。给卷命名一个可以在`Persistent Volumes`中轻松引用的名称。
- 对每个需要恢复的卷重复此步骤。
- 例如，如果恢复一个有两个副本、卷名为 pvc-01a 和 pvc-02b 的 StatefulSet，恢复过程可能如下所示：
备份名称恢复的卷

pvc-01a

statefulset-vol-0

pvc-02b

statefulset-vol-1

备份名称	恢复的卷
pvc-01a	statefulset-vol-0
pvc-02b	statefulset-vol-1

在 Kubernetes 中，为每个创建的 Longhorn 卷创建一个 Persistent Volume。给卷命名一个便于以后引用的名称，适用于 Persistent Volume Claims。storage`容量、`numberOfReplicas、storageClassName 和 volumeHandle`必须在下方替换。在示例中，我们在 Longhorn 中引用 `statefulset-vol-0 和 statefulset-vol-1，并使用 longhorn 作为我们的 storageClassName。

 apiVersion: v1
 kind: PersistentVolume
 metadata:
   name: statefulset-vol-0
 spec:
   capacity:
     storage: <size> # must match size of Longhorn volume
   volumeMode: Filesystem
   accessModes:
     - ReadWriteOnce
   persistentVolumeReclaimPolicy: Delete
   csi:
     driver: driver.longhorn.io # driver must match this
     fsType: ext4
     volumeAttributes:
       numberOfReplicas: <replicas> # must match Longhorn volume value
       staleReplicaTimeout: '30' # in minutes
     volumeHandle: statefulset-vol-0 # must match volume name from Longhorn
   storageClassName: longhorn # must be same name that we will use later
 ---
 apiVersion: v1
 kind: PersistentVolume
 metadata:
   name: statefulset-vol-1
 spec:
   capacity:
     storage: <size>  # must match size of Longhorn volume
   volumeMode: Filesystem
   accessModes:
     - ReadWriteOnce
   persistentVolumeReclaimPolicy: Delete
   csi:
     driver: driver.longhorn.io # driver must match this
     fsType: ext4
     volumeAttributes:
       numberOfReplicas: <replicas> # must match Longhorn volume value
       staleReplicaTimeout: '30'
     volumeHandle: statefulset-vol-1 # must match volume name from Longhorn
   storageClassName: longhorn # must be same name that we will use later

如果您使用加密卷，创建 PersistentVolume 时必须指定 nodePublishSecretRef 和 nodeStageSecretRef。

kind: PersistentVolume
metadata:
  name: statefulset-encrypted-vol-0
spec:
  capacity:
    storage: <size>
    volumeMode: Filesystem
    accessModes:
      - ReadWriteOnce
    persistentVolumeReclaimPolicy: Delete
    csi:
      driver: driver.longhorn.io
      fsType: ext4
      nodePublishSecretRef:
        name: <secret-name>
        namespace: <namespace>
      nodeStageSecretRef:
        name: <secret-name>
        namespace: <namespace>
      volumeAttributes:
        numberOfReplicas: <replicas>
        staleReplicaTimeout: "30"
      volumeHandle: statefulset-encrypted-vol-0
    storageClassName: longhorn

在将部署 namespace 的 StatefulSet 中，为每个 Persistent Volume 创建 PersistentVolume Claims for each。`Persistent Volume Claim`的名称必须遵循以下命名方案：

 <name of Volume Claim Template>-<name of StatefulSet>-<index>

StatefulSet Pods是零索引的。在此示例中，卷声明模板`的名称为 +`data，StatefulSet 的名称为 webapp，并且有两个副本，索引为 0 和 1。

 apiVersion: v1
 kind: PersistentVolumeClaim
 metadata:
   name: data-webapp-0
 spec:
   accessModes:
   - ReadWriteOnce
   resources:
     requests:
       storage: 2Gi # must match size from earlier
   storageClassName: longhorn # must match name from earlier
   volumeName: statefulset-vol-0 # must reference Persistent Volume
 ---
 apiVersion: v1
 kind: PersistentVolumeClaim
 metadata:
   name: data-webapp-1
 spec:
   accessModes:
   - ReadWriteOnce
   resources:
     requests:
       storage: 2Gi # must match size from earlier
   storageClassName: longhorn # must match name from earlier
   volumeName: statefulset-vol-1 # must reference Persistent Volume

创建 StatefulSet：

 apiVersion: apps/v1beta2
 kind: StatefulSet
 metadata:
   name: webapp # match this with the PersistentVolumeClaim naming scheme
 spec:
   selector:
     matchLabels:
       app: nginx # has to match .spec.template.metadata.labels
   serviceName: "nginx"
   replicas: 2 # by default is 1
   template:
     metadata:
       labels:
         app: nginx # has to match .spec.selector.matchLabels
     spec:
       terminationGracePeriodSeconds: 10
       containers:
       - name: nginx
         image: registry.k8s.io/nginx-slim:0.8
         ports:
         - containerPort: 80
           name: web
         volumeMounts:
         - name: data
           mountPath: /usr/share/nginx/html
   volumeClaimTemplates:
   - metadata:
       name: data # match this with the PersistentVolumeClaim naming scheme
     spec:
       accessModes: [ "ReadWriteOnce" ]
       storageClassName: longhorn # must match name from earlier
       resources:
         requests:
           storage: 2Gi # must match size from earlier

*结果：*恢复的数据现在应该可以从 StatefulSet 内部访问 Pods。