2个Kubernetes使用同一个Ceph存储达到Kubernetes间持久化数据迁移

水深无声 2022-02-12 16:23 261阅读 0赞

# 2个Kubernetes使用同一个Ceph存储达到Kubernetes间持久化数据迁移 #

### 文章目录 ###

*  2个Kubernetes使用同一个Ceph存储达到Kubernetes间持久化数据迁移
 *   *  1. 环境
     *  2. 迁移过程示例
     *   *  2.1 提取旧Kubernetes持久化存储
         *  2.2 将提取出来的pv、pvc导入新Kubernetes中
     *  3. 小结

当前最新Kubernetes稳定版为1.14。现在为止，还没有不同Kubernetes间持久化存储迁移的方案。但根据Kubernetes pv/pvc绑定流程和原理，只要 “存储”–>“PV”–>“PVC” 的绑定关系相同，即可保证不同间Kubernetes可挂载相同的存储，并且里面是相同数据。

## 1. 环境 ##

原来我的Kubernetes为阿里云ECS自己搭建的，现在想切换使用阿里云购买的Kubernetes。因Kubernetes中一些应用使用像1G、2G等小容量存储比较多，所以仍旧想保留原有的Ceph存储使用。

Kubernetes: v1.13.4  
Ceph: 12.2.10 luminous (stable)

2个Kubernetes存储使用storageclass管理，并连接相同Ceph集群。可参考：[Kubernetes使用Ceph动态卷部署应用][Kubernetes_Ceph]

## 2. 迁移过程示例 ##

数据依旧保留在存储中，并未真正有迁移动作，迁移只是相对于不同Kubernetes来讲。

### 2.1 提取旧Kubernetes持久化存储 ###

为了更好的看到效果，这里新建一个nginx的deploy，并使用ceph rbd做为持久化存储，然后写一些数据。

`vim rbd-claim.yaml`

kind: PersistentVolumeClaim
    apiVersion: v1
    metadata:
      name: rbd-pv-claim
    spec:
      accessModes:
        - ReadWriteOnce
      storageClassName: ceph-rbd
      resources:
        requests:
          storage: 1Gi

`vim rbd-nginx-dy.yaml`

apiVersion: extensions/v1beta1
    kind: Deployment
    metadata:
      name: nginx-rbd-dy
    spec:
      replicas: 1
      template:
        metadata:
          labels:
            name: nginx
        spec:
          containers:
            - name: nginx
              image: nginx
              imagePullPolicy: IfNotPresent
              ports:
                - containerPort: 80
              volumeMounts:
                - name: ceph-cephfs-volume
                  mountPath: "/usr/share/nginx/html"
          volumes:
          - name: ceph-cephfs-volume
            persistentVolumeClaim:
              claimName: rbd-pv-claim

# 创建pvc和deploy
    kubectl create -f rbd-claim.yaml
    kubectl create -f rbd-nginx-dy.yaml

查看结果，并写入数据至nginx持久化目录中：

pod/nginx-rbd-dy-7455884d49-rthzt   1/1     Running   0          4m31s
    [root@node5 tmp]# kubectl get pvc,pod
    NAME                                                          STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
    persistentvolumeclaim/rbd-pv-claim                            Bound    pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee   1Gi        RWO            ceph-rbd       4m37s
    
    NAME                                READY   STATUS    RESTARTS   AGE
    pod/nginx-rbd-dy-7455884d49-rthzt   1/1     Running   0          4m36s
    [root@node5 tmp]# kubectl exec -it nginx-rbd-dy-7455884d49-rthzt /bin/bash
    root@nginx-rbd-dy-7455884d49-rthzt:/# df -h
    Filesystem      Size  Used Avail Use% Mounted on
    overlay          40G   23G   15G  62% /
    tmpfs            64M     0   64M   0% /dev
    tmpfs            16G     0   16G   0% /sys/fs/cgroup
    /dev/vda1        40G   23G   15G  62% /etc/hosts
    shm              64M     0   64M   0% /dev/shm
    /dev/rbd5       976M  2.6M  958M   1% /usr/share/nginx/html
    tmpfs            16G   12K   16G   1% /run/secrets/kubernetes.io/serviceaccount
    tmpfs            16G     0   16G   0% /proc/acpi
    tmpfs            16G     0   16G   0% /proc/scsi
    tmpfs            16G     0   16G   0% /sys/firmware
    root@nginx-rbd-dy-7455884d49-rthzt:/# echo ygqygq2 > /usr/share/nginx/html/ygqygq2.html
    root@nginx-rbd-dy-7455884d49-rthzt:/# exit
    exit
    [root@node5 tmp]#

将pv、pvc信息提取出来：

[root@node5 tmp]# kubectl get pvc rbd-pv-claim -oyaml --export > rbd-pv-claim-export.yaml
    [root@node5 tmp]# kubectl get pv pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee -oyaml --export > pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee-export.yaml
    [root@node5 tmp]# more rbd-pv-claim-export.yaml 
    apiVersion: v1
    kind: PersistentVolumeClaim
    metadata:
      annotations:
        pv.kubernetes.io/bind-completed: "yes"
        pv.kubernetes.io/bound-by-controller: "yes"
        volume.beta.kubernetes.io/storage-provisioner: ceph.com/rbd
      creationTimestamp: null
      finalizers:
      - kubernetes.io/pvc-protection
      name: rbd-pv-claim
      selfLink: /api/v1/namespaces/default/persistentvolumeclaims/rbd-pv-claim
    spec:
      accessModes:
      - ReadWriteOnce
      dataSource: null
      resources:
        requests:
          storage: 1Gi
      storageClassName: ceph-rbd
      volumeMode: Filesystem
      volumeName: pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee
    status: {}
    [root@node5 tmp]# more pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee-export.yaml 
    apiVersion: v1
    kind: PersistentVolume
    metadata:
      annotations:
        pv.kubernetes.io/provisioned-by: ceph.com/rbd
        rbdProvisionerIdentity: ceph.com/rbd
      creationTimestamp: null
      finalizers:
      - kubernetes.io/pv-protection
      name: pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee
      selfLink: /api/v1/persistentvolumes/pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee
    spec:
      accessModes:
      - ReadWriteOnce
      capacity:
        storage: 1Gi
      claimRef:
        apiVersion: v1
        kind: PersistentVolumeClaim
        name: rbd-pv-claim
        namespace: default
        resourceVersion: "51998402"
        uid: d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee
      persistentVolumeReclaimPolicy: Retain
      rbd:
        fsType: ext4
        image: kubernetes-dynamic-pvc-dac8284a-6a1c-11e9-b533-1604a9a8a944
        keyring: /etc/ceph/keyring
        monitors:
        - 172.18.43.220:6789
        - 172.18.138.121:6789
        - 172.18.228.201:6789
        pool: kube
        secretRef:
          name: ceph-secret
          namespace: kube-system
        user: kube
      storageClassName: ceph-rbd
      volumeMode: Filesystem
    status: {}
    [root@node5 tmp]#

### 2.2 将提取出来的pv、pvc导入新Kubernetes中 ###

将上文中提取出来的pv和pvc传至新的Kubernetes中：

[root@node5 tmp]# rsync -avz pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee-export.yaml rbd-pv-claim-export.yaml rbd-nginx-dy.yaml 172.18.97.95:/tmp/
    sending incremental file list
    pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee-export.yaml
    rbd-nginx-dy.yaml
    rbd-pv-claim-export.yaml
    
    sent 1,371 bytes  received 73 bytes  2,888.00 bytes/sec
    total size is 2,191  speedup is 1.52
    [root@node5 tmp]#

在新的Kubernetes中导入pv、pvc：

[root@iZwz9g5ec0q4fc8iuqawr0Z tmp]# kubectl apply -f pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee-export.yaml -f rbd-pv-claim-export.yaml 
    persistentvolume/pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee created
    persistentvolumeclaim/rbd-pv-claim created
    [root@iZwz9g5ec0q4fc8iuqawr0Z tmp]# kubectl get pv pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee
    NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS     CLAIM                  STORAGECLASS   REASON   AGE
    pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee   1Gi        RWO            Retain           Released   default/rbd-pv-claim   ceph-rbd                20s
    [root@iZwz9g5ec0q4fc8iuqawr0Z tmp]# kubectl get pvc rbd-pv-claim
    NAME           STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
    rbd-pv-claim   Lost     pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee   0                         ceph-rbd       28s
    [root@iZwz9g5ec0q4fc8iuqawr0Z tmp]#

可以看到，pvc状态显示为`Lost`，这是因为在新的Kubernetes中导入pv和pvc后，它们会自动重新生成自己的`resourceVersion`和`uid`，因此在新导入的pv中的`spec.claimRef`信息为旧的：

![Alt text][]

![Alt text][Alt text 1]

为了解决新导入的pv中的`spec.claimRef`信息旧的变成新的，我们将这段信息删除，由provisioner自动重新绑定它们的关系：

这里我们做成一个脚本处理：

`vim unbound.sh`

pv=$*
    function unbound() { 
        kubectl patch pv -p '{"spec":{"claimRef":{"apiVersion":"","kind":"","name":"","namespace":"","resourceVersion":"","uid":""}}}' \
            $pv
        kubectl get pv $pv -oyaml> /tmp/.pv.yaml
        sed '/claimRef/d' -i /tmp/.pv.yaml
        #kubectl apply -f /tmp/.pv.yaml
        kubectl replace -f /tmp/.pv.yaml
    }
    
    unbound

sh unbound.sh pvc-d1cb2de6-6a1c-11e9-8124-eeeeeeeeeeee

脚本执行后，过个10秒左右，查看结果：

![Alt text][Alt text 2]

在新的Kubernetes中使用之前传的`rbd-nginx-dy.yaml`验证下，在此之前，因为使用ceph rbd，需要先解除旧Kubernetes上的pod占用该rbd：

旧Kubernetes：

[root@node5 tmp]# kubectl delete -f rbd-nginx-dy.yaml 
    deployment.extensions "nginx-rbd-dy" deleted

新Kubernetes：

![Alt text][Alt text 3]

## 3. 小结 ##

上面实验中，使用的是`RWO`的pvc，大家试想下，如果使用`RWX`，多个Kubernetes使用，这种使用场景可能有更大的作用。

Kubernetes使用过程中，pv、pvc和存储，它们的信息和绑定关系至关重要，所以可按需求当作日常备份，有了这些备份，即使Kubernetes etcd数据损坏，也可达到恢复和迁移Kubernetes持久化数据目的。

[Kubernetes_Ceph]: https://blog.51cto.com/ygqygq2/2163656
[Alt text]: /images/20220212/e6f114f7a9174a2e9659baf6eda31572.png
[Alt text 1]: /images/20220212/6780da2c30014374840f1f34619a7953.png
[Alt text 2]: /images/20220212/443986acb8204fefb22a7c0830d5f2ee.png
[Alt text 3]: /images/20220212/a1e69397fd164ac6ae1a2a75be88d81a.png