Using an Existing OBS Bucket Through a Static PV

Prerequisites

• You have created a cluster and installed the CCE Container Storage (Everest) add-on in the cluster.
• Before creating a cluster using commands, ensure kubectl is used to access the cluster. For details, see Connecting to a Cluster Using kubectl.

Constraints

• If OBS volumes are used, the owner group and permission of the mount point cannot be modified.
• CCE allows parallel file systems to be mounted using OBS SDKs or PVCs. If PVC mounting is used, the obsfs tool provided by OBS must be used. An obsfs resident process is generated each time an object storage volume generated from the parallel file system is mounted to a node, as shown in the following figure.
  Figure 1 obsfs resident process
  

  Reserve 1 GiB of memory for each obsfs process. For example, for a node with 4 vCPUs and 8 GiB of memory, an obsfs parallel file system should be mounted to no more than eight pods.

  

  • An obsfs resident process runs on a node. If the consumed memory exceeds the upper limit of the node, the node malfunctions. On a node with 4 vCPUs and 8 GiB of memory, if more than 100 pods are mounted to a parallel file system, the node will be unavailable. Control the number of pods mounted to a parallel file system on a single node.
• Kata containers do not support OBS volumes.

• Multiple PVs can use the same OBS storage volume with the following restrictions:
  • Do not mount all PVCs/PVs that use the same underlying object storage volume to a pod. This leads to a pod startup failure because not all PVCs can be mounted to the pod due to the same volumeHandle values of these PVs.
  • The persistentVolumeReclaimPolicy parameter in the PVs must be set to Retain. Otherwise, when a PV is deleted, the associated underlying volume may be deleted. In this case, other PVs associated with the underlying volume malfunction.
  • If underlying storage is repeatedly used, you are required to maintain data consistency. Enable isolation and protection for ReadWriteMany at the application layer and prevent multiple clients from writing the same file to prevent data overwriting and loss.

Using an Existing OBS Bucket on the Console

1. Log in to the CCE console and click the cluster name to access the cluster console.
2. Statically create a PVC and PV.
   1. Choose Storage in the navigation pane and click the PVCs tab. Click Create PVC in the upper right corner. In the dialog box displayed, configure the PVC parameters.

      Parameter	Description
      PVC Type	In this example, select OBS.
      PVC Name	Enter the PVC name, which must be unique in the same namespace.
      Creation Method	If underlying storage is available, create a storage volume or use an existing storage volume to statically create a PVC based on whether a PV is available. If no underlying storage is available, select Dynamically provision. For details, see Using an OBS Bucket Through a Dynamic PV. In this example, select Create new to create a PV and PVC at the same time on the console.
      PVa	Select an existing PV volume in the cluster. Create a PV in advance. For details, see "Creating a storage volume" in Related Operations. You do not need to specify this parameter in this example.
      OBSb	Click Select OBS. On the displayed page, select the OBS storage that meets your requirements and click OK.
      PV Nameb	Enter the PV name, which must be unique in the same cluster.
      Access Modeb	OBS volumes support only ReadWriteMany, indicating that a storage volume can be mounted to multiple nodes in read/write mode. For details, see Volume Access Modes.
      Reclaim Policyb	You can select Delete or Retain to specify the reclaim policy of the underlying storage when the PVC is deleted. For details, see PV Reclaim Policy. NOTE: If multiple PVs use the same OBS volume, use Retain to avoid cascading deletion of underlying volumes.
      Access Key (AK/SK)b	Custom: Customize a secret if you want to assign different user permissions to different OBS storage devices. For details, see Using a Custom Access Key (AK/SK) to Mount an OBS Volume. Only secrets with the secret.kubernetes.io/used-by = csi label can be selected. The secret type is cfe/secure-opaque. If no secret is available, click Create Secret to create one. Name: Enter a secret name. Namespace: Select the namespace where the secret is. Access Key (AK/SK): Upload a key file in .csv format. For details, see Obtaining an Access Key.
      Mount Optionsb	Enter the mounting parameter key-value pairs. For details, see Configuring OBS Mount Options.

      

      a: The parameter is available when Creation Method is set to Use existing.

      b: The parameter is available when Creation Method is set to Create new.

   2. Click Create to create a PVC and a PV.

      You can choose Storage in the navigation pane and view the created PVC and PV on the PVCs and PVs tab pages, respectively.

3. Create an application.
   1. In the navigation pane on the left, click Workloads. In the right pane, click the Deployments tab.
   2. Click Create Workload in the upper right corner. On the displayed page, click Data Storage in the Container Settings area and click Add Volume to select PVC.
      Mount and use storage volumes, as shown in Table 1. For details about other parameters, see Workloads.

      Table 1 Mounting a storage volume

      Parameter	Description
      PVC	Select an existing object storage volume.
      Mount Path	Enter a mount path, for example, /tmp. This parameter indicates the container path to which a data volume will be mounted. Do not mount the volume to a system directory such as / or /var/run. Otherwise, containers will be malfunctional. Mount the volume to an empty directory. If the directory is not empty, ensure that there are no files that affect container startup. Otherwise, the files will be replaced, causing container startup failures or workload creation failures. NOTICE: If a volume is mounted to a high-risk directory, use an account with minimum permissions to start the container. Otherwise, high-risk files on the host machine may be damaged.
      Subpath	Enter the subpath of the storage volume and mount a path in the storage volume to the container. In this way, different folders of the same storage volume can be used in a single pod. tmp, for example, indicates that data in the mount path of the container is stored in the tmp folder of the storage volume. If this parameter is left blank, the root path is used by default.
      Permission	Read-only: You can only read the data in the mounted volumes. Read/Write: You can modify the data volumes mounted to the path. Newly written data will not be migrated if the container is migrated, which may cause data loss.

      In this example, the disk is mounted to the /data path of the container. The container data generated in this path is stored in the OBS volume.

   3. After the configuration, click Create Workload.

      After the workload is created, the data in the container mount directory will be persistently stored. Verify the storage by referring to Verifying Data Persistence and Sharing.

(kubectl) Using an Existing OBS Bucket

1. Use kubectl to access the cluster.
2. Create a PV.
   1. Create the pv-obs.yaml file.

      apiVersion: v1
      kind: PersistentVolume
      metadata:
        annotations:
          pv.kubernetes.io/provisioned-by: everest-csi-provisioner
          everest.io/reclaim-policy: retain-volume-only      # (Optional) The PV is deleted while the underlying volume is retained.
        name: pv-obs       # PV name.
      spec:
        accessModes:
        - ReadWriteMany    # Access mode. The value must be ReadWriteMany for OBS.
        capacity:
          storage: 1Gi     # OBS volume capacity.
        csi:
          driver: obs.csi.everest.io        # Dependent storage driver for the mounting.
          driver: obs.csi.everest.io        # Instance type.
          volumeHandle: <your_volume_id>    # Name of the OBS volume.
          volumeAttributes:
            storage.kubernetes.io/csiProvisionerIdentity: everest-csi-provisioner
            everest.io/obs-volume-type: STANDARD
            everest.io/region: <your_region>                        # Region where the OBS volume is.
      
          nodePublishSecretRef:            # Custom secret of the OBS volume.
            name: <your_secret_name>       # Custom secret name.
            namespace: <your_namespace>    # Namespace of the custom secret.
        persistentVolumeReclaimPolicy: Retain    # Reclaim policy.
        storageClassName: csi-obs               # Storage class name.
        mountOptions: []                         # Mount options.

      Table 2 Key parameters

      Parameter	Mandatory	Description
      everest.io/reclaim-policy: retain-volume-only	No	Optional. Currently, only retain-volume-only is supported. This field is valid only when the Everest version is 1.2.9 or later and the reclaim policy is Delete. If the reclaim policy is Delete and the current value is retain-volume-only, the associated PV is deleted while the underlying storage volume is retained, when a PVC is deleted.
      fsType	Yes	Instance type. The value can be obsfs or s3fs. obsfs: Parallel file system, which is mounted using obsfs (recommended). s3fs: Object bucket, which is mounted using s3fs.
      volumeHandle	Yes	OBS volume name.
      everest.io/obs-volume-type	Yes	OBS storage class. If fsType is set to s3fs, STANDARD (standard bucket) and WARM (infrequent access bucket) are supported. This parameter is invalid when fsType is set to obsfs.
      everest.io/region	Yes	Region where the OBS bucket is deployed. For details about the value of region, see Regions and Endpoints.
      nodePublishSecretRef	No	Access key (AK/SK) used for mounting the object storage volume. You can use the AK/SK to create a secret and mount it to the PV. For details, see Using a Custom Access Key (AK/SK) to Mount an OBS Volume. An example is as follows: nodePublishSecretRef: name: secret-demo namespace: default
      mountOptions	No	Mount options. For details, see Configuring OBS Mount Options.
      persistentVolumeReclaimPolicy	Yes	A reclaim policy is supported when the cluster version is or later than 1.19.10 and the Everest version is or later than 1.2.9. The Delete and Retain reclaim policies are supported. For details, see PV Reclaim Policy. If multiple PVs use the same OBS volume, use Retain to avoid cascading deletion of underlying volumes. Delete: If everest.io/reclaim-policy is not specified, both the PV and storage resources are deleted when a PVC is deleted. If everest.io/reclaim-policy is set to retain-volume-only, when a PVC is deleted, the PV is deleted but the storage resources are retained. Retain: When a PVC is deleted, the PV and underlying storage resources are not deleted. Instead, you must manually delete these resources. After that, the PV is in the Released status and cannot be bound to the PVC again.
      storage	Yes	Storage capacity, in Gi. For OBS, this field is used only for verification (cannot be empty or 0). Its value is fixed at 1, and any value you set does not take effect for OBS.
      storageClassName	Yes	The storage class name of OBS volumes is csi-obs.

   2. Run the following command to create a PV:

      kubectl apply -f pv-obs.yaml

3. Create a PVC.
   1. Create the pvc-obs.yaml file.

      apiVersion: v1
      kind: PersistentVolumeClaim
      metadata:
        name: pvc-obs
        namespace: default
        annotations:
          volume.beta.kubernetes.io/storage-provisioner: everest-csi-provisioner
          everest.io/obs-volume-type: STANDARD
          csi.storage.k8s.io/fstype: obsfs
          csi.storage.k8s.io/node-publish-secret-name: <your_secret_name>  # Custom secret name.
          csi.storage.k8s.io/node-publish-secret-namespace: <your_namespace>        # Namespace of the custom secret.
      
      spec:
        accessModes:
        - ReadWriteMany                  # The value must be ReadWriteMany for OBS.
        resources:
          requests:
            storage: 1Gi
        storageClassName: csi-obs       # Storage class name, which must be the same as that of the PV.
        volumeName: pv-obs    # PV name.

      Table 3 Key parameters

      Parameter	Mandatory	Description
      csi.storage.k8s.io/node-publish-secret-name	No	Name of the custom secret specified in the PV.
      csi.storage.k8s.io/node-publish-secret-namespace	No	Namespace of the custom secret specified in the PV.
      storage	Yes	Requested capacity in the PVC, in Gi. For OBS, this field is used only for verification (cannot be empty or 0). Its value is fixed at 1, and any value you set does not take effect for OBS.
      storageClassName	Yes	Storage class name, which must be the same as the storage class of the PV in 1. The storage class name of OBS volumes is csi-obs.
      volumeName	Yes	PV name, which must be the same as the PV name in 1.

   2. Run the following command to create a PVC:

      kubectl apply -f pvc-obs.yaml

4. Create an application.
   1. Create a file named web-demo.yaml. In this example, the OBS volume is mounted to the /data path.

      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: web-demo
        namespace: default
      spec:
        replicas: 2
        selector:
          matchLabels:
            app: web-demo
        template:
          metadata:
            labels:
              app: web-demo
          spec:
            containers:
            - name: container-1
              image: nginx:latest
              volumeMounts:
              - name: pvc-obs-volume    #Volume name, which must be the same as the volume name in the volumes field.
                mountPath: /data  # Location where the storage volume is mounted.
            imagePullSecrets:
              - name: default-secret
            volumes:
              - name: pvc-obs-volume    # Volume name, which can be customized.
                persistentVolumeClaim:
                  claimName: pvc-obs    # Name of the created PVC.

   2. Run the following command to create a workload to which the OBS volume is mounted:

      kubectl apply -f web-demo.yaml

      After the workload is created, you can try Verifying Data Persistence and Sharing.

Verifying Data Persistence and Sharing

1. View the deployed application and files.
   1. Run the following command to view the created pod:

      kubectl get pod | grep web-demo

      Expected output:

      web-demo-846b489584-mjhm9   1/1     Running   0             46s
      web-demo-846b489584-wvv5s   1/1     Running   0             46s

   2. Run the following commands in sequence to view the files in the /data path of the pods:

      kubectl exec web-demo-846b489584-mjhm9 -- ls /data
      kubectl exec web-demo-846b489584-wvv5s -- ls /data

      If no result is returned for both pods, no file exists in the /data path.

2. Run the following command to create a file named static in the /data path:

   kubectl exec web-demo-846b489584-mjhm9 --  touch /data/static

3. Run the following command to view the files in the /data path:

   kubectl exec web-demo-846b489584-mjhm9 -- ls /data

   Expected output:

   static

4. Verify data persistence.
   1. Run the following command to delete the pod named web-demo-846b489584-mjhm9:

      kubectl delete pod web-demo-846b489584-mjhm9

      Expected output:

      pod "web-demo-846b489584-mjhm9" deleted

      After the deletion, the Deployment controller automatically creates a replica.

   2. Run the following command to view the created pod:

      kubectl get pod | grep web-demo

      The expected output is as follows, in which web-demo-846b489584-d4d4j is the newly created pod:

      web-demo-846b489584-d4d4j   1/1     Running   0             110s
      web-demo-846b489584-wvv5s    1/1     Running   0             7m50s

   3. Run the following command to check whether the files in the /data path of the new pod have been modified:

      kubectl exec web-demo-846b489584-d4d4j -- ls /data

      Expected output:

      static

      If the static file still exists, the data can be stored persistently.

5. Verify data sharing.
   1. Run the following command to view the created pod:

      kubectl get pod | grep web-demo

      Expected output:

      web-demo-846b489584-d4d4j   1/1     Running   0             7m
      web-demo-846b489584-wvv5s   1/1     Running   0             13m

   2. Run the following command to create a file named share in the /data path of either pod: In this example, select the pod named web-demo-846b489584-d4d4j.

      kubectl exec web-demo-846b489584-d4d4j --  touch /data/share

      Check the files in the /data path of the pod.

      kubectl exec web-demo-846b489584-d4d4j -- ls /data

      Expected output:

      share
      static

   3. Check whether the share file exists in the /data path of another pod (web-demo-846b489584-wvv5s) as well to verify data sharing.

      kubectl exec web-demo-846b489584-wvv5s -- ls /data

      Expected output:

      share
      static

      After you create a file in the /data path of a pod, if the file is also created in the /data path of the other pod, the two pods share the same volume.

Related Operations