CSI expanding persistent volume does not call csi.ControllerExpandVolume

[Ntr0]

What happened: Deployed a csi driver with volume expansion capability (online). Defined following storage class:

allowVolumeExpansion: true
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
  name: ionos-enterprise-hdd
parameters:
  type: HDD
provisioner: cloud.ionos.com
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer

Created a pvc:

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: nginx-data
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi
  storageClassName:  ionos-enterprise-hdd

Increasing the requested storage parameter in the pvc works as expected: First ControllerExpandVolume is called, then NodeExpandVolume. But increasing the storage size in the underlying pv has the effect, that only NodeExpandVolume is called, (which of course does not work, since ControllerExpandVolume is required beforehands). What you expected to happen: If it is actually allowed to change the persistent volume, than ControllerExpandVolume must be called.

How to reproduce it (as minimally and precisely as possible):

• use a csi driver that supports expand volume
• adopt provided config yamls for the csi driver
• apply configs
• increase the capactity.storage property of the created pv

Anything else we need to know?:

Environment:

• Kubernetes version (use kubectl version): 1.15.0
• Cloud provider or hardware configuration: Ionos Enterprise Cloud
• OS (e.g: cat /etc/os-release): CentOS 7
• Kernel (e.g. uname -a): 3.10.0-957.12.1.el7.x86_64 #1 SMP Mon Apr 29 14:59:59 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
• Install tools:
• Network plugin and version (if this is a network-related bug):
• Others:

[Ntr0]

@kubernetes/sig-storage-bugs

[k8s-ci-robot]

@Ntr0: Reiterating the mentions to trigger a notification: @kubernetes/sig-storage-bugs

In response to [this](https://github.com/kubernetes/kubernetes/issues/79716#issuecomment-508075611): >@kubernetes/sig-storage-bugs Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes/test-infra](https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:) repository.

[msau42]

I'm unsure increasing PV size is a supported sequence. cc @gnufied

[Ntr0]

me neither. And I would be fine with the solution, that it is not supported. But then NodeExpandVolume should not be called, right?

[gnufied]

When you manually increase the PV size without expanding the underlying volume, you have basically broken the contract of a PV. PV should always store actual size of the volume since PV has no PV.Status.Size field.

Calling NodeExpandVolume is right thing to do because PV has bigger size than what is stored in PVC's status.

[Ntr0]

Alright, thanks for the clarification.