Let's perform the following steps to get an NFS provider functional using the Rook NFS provider option:

1. Clone the Rook repository:

$ git clone https://github.com/rook/rook.git
$ cd rook/cluster/examples/kubernetes/nfs/

2. Deploy the Rook NFS operator:

$ kubectl create -f operator.yaml

3. Confirm that the operator is running:

$ kubectl get pods -n rook-nfs-system
NAME READY STATUS RESTARTS AGE
rook-nfs-operator-54cf68686c-f66f5 1/1 Running 0 51s
rook-nfs-provisioner-79fbdc79bb-hf9rn 1/1 Running 0 51s

4. Create a namespace, rook-nfs:

$ cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Namespace
metadata:
 name: rook-nfs
EOF

5. Make sure that you have defined your preferred storage provider as the default storage class. In this recipe, we are using openebs-cstor-default, defined in persistent storage using the OpenEBS recipe.
6. Create a PVC:

$ cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: nfs-default-claim
  namespace: rook-nfs
spec:
  accessModes:
  - ReadWriteMany
  resources:
    requests:
      storage: 1Gi
EOF

7. Create the NFS instance:

$ cat <<EOF | kubectl apply -f -
apiVersion: nfs.rook.io/v1alpha1
kind: NFSServer
metadata:
  name: rook-nfs
  namespace: rook-nfs
spec:
  serviceAccountName: rook-nfs
  replicas: 1
  exports:
  - name: share1
    server:
      accessMode: ReadWrite
      squash: "none"
    persistentVolumeClaim:
      claimName: nfs-default-claim
  annotations:
  # key: value
EOF

8. Verify that the NFS pod is in the Running state:

$ kubectl get pod -l app=rook-nfs -n rook-nfs 
NAME       READY  STATUS  RESTARTS AGE
rook-nfs-0 1/1    Running 0        2m

By observing the preceding command, an NFS server instance type will be created.