External-storage: nfs-client-provisioner volume cannot be expanded

[chanjarster]

Trying to expand a PVC got warning:

Ignoring the PVC: didn't find a plugin capable of expanding the volume; waiting for an external controller to process this PVC.

Create a PVC of 1Gi size:

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: myclaim
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  storageClassName: nfs-client
EOF

Check that pvc, it's successfully bound:

$ kubectl get pvc myclaim
NAME       STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
myclaim    Bound    pvc-6ef8eda2-efb5-11e9-9bef-005056bd0410   1Gi        RWO            nfs-client     8s

$ kubectl describe pvc myclaim
...
Events:
  Type    Reason                 Age                From                                                                                                               Message
  ----    ------                 ----               ----                                                                                                               -------
  Normal  Provisioning           61s                cluster.local/nfs-client-provisioner_nfs-client-provisioner-58487c669c-jjqpq_a9da7c7e-ec08-11e9-9af1-2228a80fe4ad  External provisioner is provisioning volume for claim "default/myclaim"
  Normal  ExternalProvisioning   61s (x2 over 61s)  persistentvolume-controller                                                                                        waiting for a volume to be created, either by external provisioner "cluster.local/nfs-client-provisioner" or manually created by system administrator
  Normal  ProvisioningSucceeded  61s                cluster.local/nfs-client-provisioner_nfs-client-provisioner-58487c669c-jjqpq_a9da7c7e-ec08-11e9-9af1-2228a80fe4ad  Successfully provisioned volume pvc-6ef8eda2-efb5-11e9-9bef-005056bd0410

Try to expand PVC to size of 2Gi:

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: myclaim
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi
  storageClassName: nfs-client
EOF

Check it, and it's still size of 1Gi:

$ kubectl get pvc myclaim
NAME      STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
myclaim   Bound    pvc-6ef8eda2-efb5-11e9-9bef-005056bd0410   1Gi        RWO            nfs-client     2m37s

Check the events:

$ kubectl describe pvc myclaim
Events:
  Type     Reason                 Age                    From                                                                                                               Message
  ----     ------                 ----                   ----                                                                                                               -------
  Normal   Provisioning           4m14s                  cluster.local/nfs-client-provisioner_nfs-client-provisioner-58487c669c-jjqpq_a9da7c7e-ec08-11e9-9af1-2228a80fe4ad  External provisioner is provisioning volume for claim "default/myclaim"
  Normal   ExternalProvisioning   4m14s (x2 over 4m14s)  persistentvolume-controller                                                                                        waiting for a volume to be created, either by external provisioner "cluster.local/nfs-client-provisioner" or manually created by system administrator
  Normal   ProvisioningSucceeded  4m14s                  cluster.local/nfs-client-provisioner_nfs-client-provisioner-58487c669c-jjqpq_a9da7c7e-ec08-11e9-9af1-2228a80fe4ad  Successfully provisioned volume pvc-6ef8eda2-efb5-11e9-9bef-005056bd0410
  Warning  ExternalExpanding      19s                    volume_expand                                                                                                      Ignoring the PVC: didn't find a plugin capable of expanding the volume; waiting for an external controller to process this PVC.

BTW Storage class enabled expansion:

$ kubectl get storageclasses.storage.k8s.io -o nfs-client
allowVolumeExpansion: true
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  creationTimestamp: "2019-10-12T09:19:04Z"
  labels:
    app: nfs-client-provisioner
    chart: nfs-client-provisioner-1.2.6
    heritage: Tiller
    io.cattle.field/appId: nfs-client-provisioner
    release: nfs-client-provisioner
  name: nfs-client
  resourceVersion: "4010231"
  selfLink: /apis/storage.k8s.io/v1/storageclasses/nfs-client
  uid: 55e63667-ecd1-11e9-9bef-005056bd0410
parameters:
  archiveOnDelete: "false"
provisioner: cluster.local/nfs-client-provisioner
reclaimPolicy: Delete
volumeBindingMode: Immediate

[wongma7]

Yes, the nfs-client-provisioner is not capable of expanding volumes. In fact, it does not enforce the size of volumes at all, so a PV that says 1Gi may in fact have contain/write more than 1Gi of data in its path. AFAIK, there is no standard quota/limit mechanism for NFS. Apologies if this is not clear.

[chanjarster]

I got it, thanks