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

Last Updated:Apr 10, 2024

After you register external Kubernetes clusters to Container Service for Kubernetes (ACK), you can use the backup center of ACK to back up applications and data in the clusters, and restore the backup files in ACK clusters. This topic describes how to use the backup center of ACK to migrate applications from external Kubernetes clusters to ACK clusters.

Prerequisites

  • A registered cluster is created and an external cluster whose Kubernetes version is later than 1.16 is registered to ACK by using the registered cluster. For more information, see Create a registered cluster in the ACK console.

  • An ACK cluster that is used to restore applications is deployed in the same region as the registered cluster, and the Kubernetes version of the cluster is 1.18 or later. For more information, see Create an ACK managed cluster and Create an ACK dedicated cluster.

    Important
    • The restore cluster must use the Container Storage Interface (CSI) plug-in. Application restoration is not supported in clusters that use FlexVolume or use csi-compatible-controller and FlexVolume.

    • The backup center is used to back up and restore applications. Before you run a restore task, you must install and configure system components in the restore cluster. Example:

      • aliyun-acr-credential-helper: You need to grant permissions to the restore cluster and configure acr-configuration.

      • alb-ingress-controller: You need to configure an ALBConfig.

  • The cluster backup feature is enabled for the registered cluster and the ACK cluster that you created. For more information, see Install migrate-controller and grant permissions.

  • A route is configured that points to the internal network of the region in which the Object Storage Service (OSS) bucket for the registered cluster resides if the cluster is connected to a virtual private cloud (VPC) by using Cloud Enterprise Network (CEN), Express Connect, or VPN connections. For more information, see Internal endpoints of OSS buckets and VIP ranges.

  • Cloud Backup is activated. For more information, see Cloud Backup.

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:

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