Container Service for Kubernetes:Migrate applications from external Kubernetes clusters to ACK clusters

Scenarios

Cloud Backup for disaster recovery: You need to back up data, restore backup files, and migrate applications and data to the cloud.

Usage notes

• Before you back up the data in the external cluster, you must create persistent volumes (PVs) and persistent volume claims (PVCs) to mount local volumes to the cluster. The Container Storage Interface (CSI) plug-in provided by Alibaba Cloud allows you to mount volumes to registered clusters. For more information, see Overview.

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

Before you begin

In this example, a MySQL application that runs in an external cluster is backed up and then the backup file is restored in an ACK cluster. Before you migrate the application, you must make sure that the registered cluster and the ACK cluster are deployed in the same region and both have the cluster backup feature enabled. You must also make sure that the following conditions are met:

• Registered cluster: A Resource Access Management (RAM) user is created and granted the permissions to access OSS and Cloud Backup. A Secret named alibaba-addon-secret is created in the csdr namespace of the registered cluster to store the AccessKey ID and AccessKey secret of the RAM user.

  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

• ACK cluster:

  • If you use an ACK managed cluster, make sure that Cloud Backup is activated and an OSS bucket named cnfs-oss-**** is created.

  • If you use an ACK dedicated cluster, make sure that the worker RAM role of the cluster has the 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 cluster or registered cluster.

Step 1: Deploy an application in the external cluster

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

   kubectl create namespace test1

2. Create a file named app-mysql.yaml and add the following content to the file.

   Replace <your-hostname> with the name of the node that you want to back up. Set the username and password parameters to the username and password that are used to log on to the 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: mysql:5.7
           env:
           - name: MYSQL_ROOT_PASSWORD
             valueFrom:
               secretKeyRef:
                 name: mysql-pass
                 key: password
           ports:
           - containerPort: 80
             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> # Specify the name of the node that you want 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****             # Replace the value with the username that is used to log on to the MySQL application that you want to back up. 
     password: dGVzdDEt****     # Replace the value with the password that is used to log on to the MySQL application that you want to back up.

3. Run the following command to create a MySQL application, a PV, and a PVC. The PV and PVC are used to mount a local disk to the MySQL application.

   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

4. Run the following command to check whether the MySQL application is created:

   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 MySQL application and data in the external cluster

You can register the external cluster to ACK and then perform the backup operation in the registered cluster. To back up the MySQL application and data, perform the following operations:

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

2. Create a real-time backup task named MySQL in the registered cluster. For more information, see Create a backup plan or back up instantly.

   Set Name to MySQL, select the backup vault that you created in the previous step from the Backup Vaults drop-down list, and then select test1 from the Backup Namespaces drop-down list.

3. On the Application Backup page, click the Backup Records tab. If the status of the MySQL backup task changes from InProgress to Completed, the MySQL application and data are backed up.

Step 3: Restore the backup file in the ACK cluster

In this example, the StorageClass of an external cluster is converted to alibabacloud-cnfs-nas. This example shows how to restore the backup file of the MySQL application in the ACK cluster. Perform the following steps:

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

   Parameter	Example
   Name	mysql-restore.
   Backup Vaults	Select the backup vault that you created. After you select a backup vault, click Initialize Backup Vault to associate the restore cluster with the backup vault.
   Select Backup	Select MySQL.
   Reset Namespace	Change from test1 to test2.
   StorageClass Conversion	Select the alibabacloud-cnfs-nas StorageClass for the example-pvc PVC in the list of converted PVCs.

2. Click View Restoration Records on the right side of Restore. If the status of the mysql-restore restoration task changes from InProgress to Completed, the MySQL application and data are restored.

3. Run the following command in the ACK cluster to check whether 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 command in the ACK cluster to check whether the data is restored.

   1. Run the following command to check whether the StorageClass of the PVC is changed to alibaba-cnfs-nas:

      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. Run the following command to check whether the example-pvc PVC is mounted to the MySQL application:

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

      Expected output:

      Used By:       mysql-sts-0