Set default volume type in storage class

[js185692]

We have many StatefulSet workloads requiring the provisioner to create local volumes during provisioning. For several of these StatefulSets, we are unable to add the volumeType annotation which results in us having to use hostPath volumes which is unacceptable for us. Furthermore, it is tedious and error-prone to have to specify the volumeType annotation on every single PVC and would therefore prove useful to be able to specify a default volume type on the StorageClass.

I propose the addition of an annotation called defaultVolumeType on storage classes which will set the volume type for all volumes using that class. The annotation for the PVC can still be applied and will supersede the annotation on the storage class.

A basic example of a StorageClass with this annotation:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: local-path
  annotations:
    defaultVolumeType: local
    storageclass.kubernetes.io/is-default-class: true

[derekbit]

In general, LGTM.

Suggest having a test case.

[derekbit]

LGTM.
Will test and merge it tomorrow.

[derekbit]

@js185692
Thanks for your contribution.