Add documentations for volume resizing

docs/README.md

@@ -66,6 +66,7 @@ Following sections are Kubernetes specific. If you are Kubernetes user, use foll
 * **Block Volume** - consumes the EBS volume as a raw block device for latency sensitive application eg. MySql
 * **Volume Snapshot** - creating volume snapshots and restore volume from snapshot.
 * **NVMe** - consume NVMe EBS volume from EC2 [Nitro instance](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html#ec2-nitro-instances).
+* **Volume Resizing** - expand the volume resize.
 
 ## Prerequisites
 * If you are managing EBS volumes using static provisioning, get yourself familiar with [EBS volume](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AmazonEBS.html).
@@ -107,6 +108,7 @@ Make sure you follow the [Prerequisites](README.md#Prerequisites) before the exa
 * [Block Volume](../examples/kubernetes/block-volume)
 * [Volume Snapshot](../examples/kubernetes/snapshot)
 * [Configure StorageClass](../examples/kubernetes/storageclass)
+* [Volume Resizing](../examples/kubernetes/resizing)
 
 ## Migrating from in-tree EBS plugin
 Starting from Kubernetes 1.14, CSI migration is supported as alpha feature. If you have persistence volumes that are created with in-tree `kubernetes.io/aws-ebs` plugin, you could migrate to use EBS CSI driver. To turn on the migration, set `CSIMigration` and `CSIMigrationAWS` feature gates to `true` for `kube-controller-manager` and `kubelet`.

examples/kubernetes/resizing/README.md

@@ -0,0 +1,41 @@
+## Volume Resizing
+This example shows how to resize EBS persistence volume using volume resizing features.
+
+Note that CSI volume resizing is still alpha as of Kubernetes 1.15.
+
+## Usage
+1. Add `allowVolumeExpansion: true` in the StorageClass spec in [example manifest](./specs/example.yaml) to enable volume expansion. You can only expand a PVC if its storage class’s allowVolumeExpansion field is set to true
+
+2. Deploy the example:
+```sh
+kubectl apply -f specs/
+``` 
+
+3. Verify the volume is created and Pod is running:
+```sh
+kubectl get pv
+kubectl get po app
+```
+
+4. Expand the volume size by increasing the capacity in PVC's `spec.resources.requests.storage`:
+```sh
+kubectl edit pvc ebs-claim
+```
+Save the result at the end of the edit.
+
+5. Verify that both the persistence volume and persistence volume claim are resized:
+```sh
+kubectl get pv
+kubectl get pvc
+```
+You should see that both should have the new value relfected in the capacity fields.
+
+6. Verify that the application is continuously running without any interruption:
+```sh
+kubectl exec -it app cat /data/out.txt
+```
+
+7. Cleanup resources:
+```
+kubectl delete -f specs/
+```

examples/kubernetes/resizing/spec/example.yaml

@@ -0,0 +1,36 @@
+kind: StorageClass
+apiVersion: storage.k8s.io/v1
+metadata:
+  name: resize-sc
+provisioner: ebs.csi.aws.com
+allowVolumeExpansion: true
+---
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: ebs-claim
+spec:
+  accessModes:
+    - ReadWriteOnce
+  storageClassName: resize-sc
+  resources:
+    requests:
+      storage: 4Gi
+---
+apiVersion: v1
+kind: Pod
+metadata:
+  name: app
+spec:
+  containers:
+  - name: app
+    image: centos
+    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: ebs-claim