Expanding a pod volume

To expand a volume:

1. Enable volume expansion.
2. Create a PersistentVolumeClaim.
3. Create a pod with a dynamically provisioned volume.
4. Request volume expansion.
5. Check the pod with the volume.

Before you start, install kubectl and configure it to work with the created Managed Service for Kubernetes cluster.

Enable volume expansionEnable volume expansion

To enable the volume expansion feature, make sure the storage class (StorageClass) description contains the allowVolumeExpansion: true parameter. In Managed Service for Kubernetes storage, this feature is enabled by default:

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: yc-network-hdd
provisioner: disk-csi-driver.mks.ycloud.io
volumeBindingMode: WaitForFirstConsumer
parameters:
  type: network-hdd
  csi.storage.k8s.io/fstype: ext4
allowVolumeExpansion: true
reclaimPolicy: Delete

Create a PersistentVolumeClaim objectCreate a PersistentVolumeClaim object

1. Save the following PersistentVolumeClaim creation specification to a YAML file named pvc-expansion.yaml.

   To learn more about the PersistentVolumeClaim creation specification, see the Kubernetes documentation.

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: pvc-expansion
   spec:
     accessModes:
       - ReadWriteOnce
     storageClassName: yc-network-hdd
     resources:
       requests:
         storage: 1Gi
   

2. Create the PersistentVolumeClaim object:

   kubectl create -f pvc-expansion.yaml
   

   Result:

   persistentvolumeclaim/pvc-expansion created
   

Create a pod with a dynamically provisioned volumeCreate a pod with a dynamically provisioned volume

1. Save the following pod creation specification to a YAML file named pod.yaml.

   To learn more about the pod creation specification, see the Kubernetes documentation.

   apiVersion: v1
   kind: Pod
   metadata:
     name: pod
   spec:
     containers:
     - name: app
       image: ubuntu
       command: ["/bin/sh"]
       args: ["-c", "while true; do echo $(date -u) >> /data/out.txt; sleep 5; done"]
       volumeMounts:
       - name: persistent-storage
         mountPath: /data
     volumes:
     - name: persistent-storage
       persistentVolumeClaim:
         claimName: pvc-expansion
   

2. Create a pod:

   kubectl create -f pod.yaml
   

   Result:

   pod/pod created
   

Request volume expansionRequest volume expansion

1. Edit the spec.resources.requests.storage field of the PersistentVolumeClaim object:

   kubectl patch pvc pvc-expansion -p '{"spec":{"resources":{"requests":{"storage":"2Gi"}}}}'
   

2. Wait a few minutes for the volume to expand. Check the change results:

   kubectl get pvc pvc-expansion -o yaml
   

   The status.capacity.storage field shows the requested volume size:

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
   ...
   spec:
     accessModes:
     - ReadWriteOnce
     resources:
       requests:
         storage: 2Gi
   ...
   status:
     accessModes:
     - ReadWriteOnce
     capacity:
       storage: 2Gi
   ...
   

Check the pod with the volumeCheck the pod with the volume

Check the pod status:

kubectl get pod pod -o yaml

The pod is running. The status section shows no container restarts.