Managing CBS templates by using a StorageClass

Last updated: 2020-09-04 10:26:22

    Operation Scenarios

    A cluster admin can use StorageClass to define different storage classes for Tencent Kubernetes Engine (TKE) clusters. TKE provides the block storage StorageClass by default. You can use both StorageClass and PersistentVolumeClaim to dynamically create required storage resources.

    This document describes how to create a StorageClass of the Cloud Block Storage (CBS) type by using the console and Kubectl, and how to customize the template required by CBS disks.

    Directions

    Console operation instructions

    Creating a StorageClass

    1. Log in to the Tencent Kubernetes Engine console and select Cluster in the left sidebar to go to the Cluster Management page.
    2. Click the ID of the cluster for which a StorageClass needs to be created to go to the cluster details page.
    3. Choose Storage -> StorageClass in the left sidebar to go to the StorageClass page, as shown in the following figure.
    4. Click Create to go to the Create a StorageClass page, where you can set the parameters as required, as shown in the following figure.

      Main parameters are described as follows:
      • Name: set a custom name. This document uses cbs-test as an example.
      • Provisioner: select Cloud Block Storage.
      • Availability Zone: select the availability zones that support CBS disks in the current region as required.
      • Billing mode: the elastic pay-as-you-go billing mode is provided. It allows you to enable and terminate instances at any time. The instances are billed based on actual usage, and the delete and retain reclaim policies are supported.
    • Disk Type: Premium Cloud Disk and SSD Cloud Disk are supported. Different availability zones may have different disk types. For more information, see Cloud Disk Types. Select a disk type as prompted by the console.

    • Reclaim Policy: the reclaim policy for cloud disks. Generally, the Delete and Retain reclaim policies are provided, which depends on the selected billing mode. For data security, we recommend that you select Retain.

    • Volume Binding Mode: two modes are available: Bind Now and Wait for Scheduling. Different modes support different volume binding policies. Refer to the following information to select the appropriate mode:

      • Bind Now: PVCs created via the storageclass will be directly bound with the PV and allocated.
      • Wait for Scheduling: PVCs created via the storageclass will not be bound with the PV and allocated until the pod that uses the PVCs is created.
    • Scheduled Snapshot: setting scheduled snapshot policy can effectively protect data security, but data backup will generate certain fees. For more information, see Snapshot Overview.

      Note:

      The default-policy configuration provided by TKE for backup includes: the date of backup execution, time point of backup execution, and backup retention period.

    1. Click Create a StorageClass to complete the process.

    Creating a PVC by using a specified StorageClass

    1. On the Cluster Management page, select the ID of the cluster for which a PVC needs to be created.

    2. On the cluster details page, choose Storage -> PersistentVolumeClaim in the left sidebar to go to the PersistentVolumeClaim page, as shown in the following figure.

    3. Click Create to go to the Create a PersistentVolumeClaim page, where you can set key PVC parameters as required, as shown in the following figure.

      Main parameters are described as follows:

      • Name: set a custom name. This document uses cbs-pvc as an example.

      • Namespace: select default.

      • Provisioner: select CBS.

      • R/W permission: CBS disks only support Single machine read and write.

      • StorageClass: specify a StorageClass as required. This document uses the cbs-test created in the step of Creating a StorageClass as an example.

        Note:

        • The PVC and PV will be bound to the same StorageClass.
        • If you do not specify a StorageClass, the value of StorageClass for the corresponding PVC is empty, and the value of the storageClassName field in the corresponding YAML file is a null string.
      • PersistVolume: specify a PersistentVolume as required. In the example in this document, no PersistentVolume is specified.

        Note:

        • The system first searches the current cluster to see whether there are PVs that meet the binding rules. If no, the system dynamically creates a PV to be bound based on the PVC and the selected StorageClass.
        • If StorageClass is not specified, then PersistVolume must be specified.
        • No PersistentVolume is specified.
      • Disk Type: based on the selected StorageClass, the available disk types are displayed: Premium Cloud Disk and SSD Cloud Disk.

      • Capacity: if no PersistentVolume is specified, specify the expected cloud disk capacity.

      • Cost: based on the above parameters, calculate the cost of the corresponding cloud disk. For more information, see Billing Modes.

    4. Click Create a PersistentVolumeClaim to complete the creation process.

    Creating a StatefulSet to mount a PVC volume

    Note:

    This step creates a StatefulSet workload as an example.

    1. On the details page of the target cluster, choose Workload -> StatefulSet in the left sidebar to go to the StatefulSet page.
    2. Click Create to go to the Create Workload page. For more information, see Creating a StatefulSet. Then, mount a volume as required, as shown in the following figure.
      • Volume (optional):
        • Mount Method: select Use existing PVC.
        • Volume name: set a custom name. This document uses cbs-vol as an example.
        • Select PVC: select an existing PVC. This document uses the cbs-pvc, which you created in the step of Creating a PVC by using a specified StorageClass, as an example.
      • Containers in the pod: click Add Mount Point to set a mount point.
        • Volume: select the volume cbs-vol that you added in this step.
        • Destination Path: enter a destination path. This document uses /cache as an example.
        • Sub-path: mount only a sub-path or a single file in the selected volume, such as /data or /test.txt.
    3. Click Create Workload to complete the process.

    Kubectl operation instructions

    You can use the sample template in this document to create a StorageClass by using Kubectl.

    Creating a StorageClass

    The following sample YAML file is used to create a StorageClass with the default name of cbs in a cluster.

    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
      # annotations:
      #   storageclass.beta.kubernetes.io/is-default-class: "true"
      # If this line is present, it will become the default-class, and if you do not specify a type when creating a PVC, this type will be used automatically.
      name: cloud-premium
    provisioner: cloud.tencent.com/qcloud-cbs ## The provisioner coming with the TKE cluster
    parameters:
      type: CLOUD_PREMIUM
      # CLOUD_BASIC, CLOUD_PREMIUM, and CLOUD_SSD are supported. If it is not recognized, CLOUD_BASIC is used by default.
      # paymode: POSTPAID
      # paymode: the billing method of the cloud disk. The default value is POSTPAID (pay-as-you-go, which supports the **Retain** and **Delete** reclaim policies. **Retain** is only available in clusters later than V1.8).
      # aspid:asp-123
      # You can specify a snapshot policy. After the cloud disk is created, it will be automatically bound to this policy. Binding failure does not affect the creation.

    The following table lists the supported parameters.

    Parameter Description
    type StorageClass type, which can be CLOUD_BASIC, CLOUD_PREMIUM, or CLOUD_SSD.
    zone Availability zone. If an availability zone is specified, the cloud disk is created in this availability zone. If no availability zone is specified, the availability zones of all nodes are obtained and one is selected at random. For the identifiers of all Tencent Cloud regions, see Regions and Availability Zones.
    paymode The billing method of the cloud disk. The default value is POSTPAID (pay-as-you-go), which supports the **Retain** and **Delete** reclaim policies. **Retain** is only available in clusters later than V1.8.
    aspid Snapshot policy ID. The created cloud disk will be automatically bound with this policy. Binding failure does not affect the creation of the cloud disk.

    Creating a multi-pod StatefulSet

    You can use a cloud disk to create a multi-pod StatefulSet. The sample YAML file is as follows:

    apiVersion: apps/v1beta1
    kind: StatefulSet
    metadata:
      name: web
    spec:
      serviceName: "nginx"
      replicas: 3
      template:
        metadata:
          labels:
            app: nginx
        spec:
          terminationGracePeriodSeconds: 10
          containers:
          - name: nginx
            image: nginx
            ports:
            - containerPort: 80
              name: web
            volumeMounts:
            - name: www
              mountPath: /usr/share/nginx/html
      volumeClaimTemplates: # the system automatically creates a PVC and then automatically creates a PV.
      - metadata:
          name: www
        spec:
          accessModes: [ "ReadWriteOnce" ]
          storageClassName: cloud-premium
          resources:
            requests:
              storage: 10Gi

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