Container Service for Kubernetes:Migrate applications from a self-managed Kubernetes cluster to an ACK cluster

Scenarios

Cloud backup and disaster recovery: an integrated solution for backup, disaster recovery, and migration that helps you quickly migrate applications to the cloud and implement data disaster recovery. For more information, see Overview of registered clusters.

Notes

• When you back up data from an external cluster, you must mount a local volume as a PV and a PVC. The Alibaba Cloud CSI plugin supports mounting volumes on an ACK One registered cluster. For more information, see Local volumes.

• The ACK One registered cluster, ACK cluster, and OSS bucket must be in the same region.

Preparations

This topic uses a MySQL application as an example to describe how to deploy and back up the application in an external cluster, and then restore it to an ACK cluster. Before migrating the application, make sure that the ACK One registered cluster and the ACK cluster are in the same region, the cluster backup feature is enabled for both clusters, and the following requirements are met:

• For the ACK One registered cluster: Create a RAM user and grant it permissions on OSS and Cloud Backup. Then, use the AccessKey ID and AccessKey secret of the RAM user to create a Secret named alibaba-addon-secret in the csdr namespace of the ACK One registered cluster.

  Run the following command to check whether the alibaba-addon-secret Secret exists.

  kubectl get secret alibaba-addon-secret -n csdr

  Expected output:

  alibaba-addon-secret   Opaque   2      5d22h

• For the ACK cluster:

  • If you use an ACK managed cluster, make sure that the Cloud Backup service is activated and a bucket whose name starts with cnfs-oss-**** is created.

  • If you use an ACK dedicated cluster, make sure that the worker RAM role has permissions to access OSS and Cloud Backup. For more information, see Grant OSS permissions to an ACK dedicated cluster and Grant Cloud Backup permissions to an ACK dedicated or registered cluster.

Step 1: Deploy the application in the external cluster

1. Run the following command to create the test1 namespace:

   kubectl create namespace test1

2. On a node that you want to back up, run the following command to create a mount path:

   mkdir /mnt/disk

3. Create a file named app-mysql.yaml with the following content. Replace <YOUR-HOSTNAME> with the name of the node that you want to back up. Replace the values of username and password with the Base64-encoded username and password of the MySQL application.

   apiVersion: apps/v1
   kind: StatefulSet
   metadata:
     name: mysql-sts
     namespace: test1
   spec:
     selector:
       matchLabels:
         app: mysql-sts
     serviceName: mysql-sts
     template:
       metadata:
         labels:
           app: mysql-sts
       spec:
         containers:
         - name: mysql-sts
           image: registry.cn-hangzhou.aliyuncs.com/arms-docker-repo/arms-demo-mysql:v0.1
           env:
           - name: MYSQL_ROOT_PASSWORD
             valueFrom:
               secretKeyRef:
                 name: mysql-pass
                 key: password
           ports:
           - containerPort: 3306
             name: mysql-sts
           volumeMounts:
           - name: mysql
             mountPath: /var/lib/mysql
         volumes:
           - name: mysql
             persistentVolumeClaim:
               claimName: example-pvc
   ---
   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: example-pv
   spec:
     capacity:
       storage: 100Gi
     volumeMode: Filesystem
     accessModes:
     - ReadWriteOnce
     persistentVolumeReclaimPolicy: Delete
     storageClassName: local-storage
     local:
       path: /mnt/disk
     nodeAffinity:
       required:
         nodeSelectorTerms:
         - matchExpressions:
           - key: kubernetes.io/hostname
             operator: In
             values:
             - <YOUR-HOSTNAME> # The name of the node to back up.
   ---
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: example-pvc
     namespace: test1
   spec:
     accessModes:
     - ReadWriteOnce
     resources:
       requests:
         storage: 25Gi
     storageClassName: local-storage
     volumeName: example-pv
   ---
   apiVersion: v1
   kind: Secret
   metadata:
     name: mysql-pass
     namespace: test1
   type: Opaque
   data:
     username: dGVz****             # The Base64-encoded username of the MySQL application to be backed up. Replace the value with the actual username.
     password: dGVzdDEt****     # The Base64-encoded password of the MySQL application to be backed up. Replace the value with the actual password.

4. Run the following command to deploy the MySQL application, mount the local disk as a PV, and create the related PV and PVC:

   kubectl create -f app-mysql.yaml

   Expected output:

   statefulset.apps/mysql-sts created
   persistentvolume/example-pv created
   persistentvolumeclaim/example-pvc created
   secret/mysql-pass created

5. Run the following command to check whether the MySQL application is deployed:

   kubectl get pod -n test1 | grep mysql-sts

   Expected output:

   mysql-sts-0   1/1     Running   1 (4m51s ago)   4m58s

Step 2: Back up the application and data

The external cluster is connected to the ACK One registered cluster. You can perform backup tasks in the ACK One registered cluster.

1. Create a backup vault in the ACK One registered cluster. For more information, see Create a backup vault.

2. Create an instant backup named mysql in the ACK One registered cluster. For more information, see Create a backup plan or an instant backup.

   Set Name to mysql. For Backup Vaults, select the vault from the previous step. For Backup Namespaces, select test1.

3. On the Application Backup page, click the Backup Records tab to view the status of the mysql-backup task. When the status changes from InProgress to Completed, the backup is complete.

Step 3: Restore the application in the ACK cluster

This section shows how to restore the MySQL application in the ACK cluster and convert its storage to the alibabacloud-cnfs-nas StorageClass. Perform the following steps:

1. Create a restore task named mysql-restore to deploy the MySQL application to the test2 namespace of the ACK cluster and convert the StorageClass to alibabacloud-cnfs-nas. For more information, see Restore applications and data volumes.

   Parameter	Value
   Name	mysql-restore
   Backup Vaults	Select the backup vault that you created. If the Initialize Backup Vault button appears, click it and wait for the backup records to synchronize to the cluster.
   Select Backup	mysql
   Reset Namespace	Remap the namespace from test1 to test2.
   StorageClass Conversion	In the list of PVCs to be converted, select the alibabacloud-cnfs-nas StorageClass for example-pvc.

2. To the right of Restore, click View Restoration Records. The restoration is complete when the task status changes from InProgress to Completed.

3. Run the following command in the ACK cluster to verify that the MySQL application is deployed:

   kubectl get pod -n test2 | grep mysql-sts

   Expected output:

   mysql-sts-0   1/1     Running   0          4s

4. Run the following commands in the ACK cluster to verify that the data is restored:

   1. Verify that the data is restored to the alibabacloud-cnfs-nas StorageClass.

      kubectl get pvc -n test2 | grep example-pvc

      Expected output:

      example-pvc   Bound    nas-acde4acd-59b6-4332-90af-b74ef6******   25Gi       RWO            alibabacloud-cnfs-nas   31m

   2. Verify that example-pvc is mounted to the MySQL application.

      kubectl describe pvc example-pvc -n test2 | grep "Used By"

      Expected output:

      Used By:       mysql-sts-0