doc: initial/partial instructions for using NFS examples

The README explains some of the requirements and basic configuration for
using the NFS-provisioner. When more deployment artifacts are added, the
README will get extended.

The Rook CephNFS example is included, as it is the easiest to get
started with dynamic provisioning of NFS-volumes.

Signed-off-by: Niels de Vos <ndevos@redhat.com>

examples/nfs/README.md

@@ -0,0 +1,70 @@
+# Dynamic provisioning with NFS
+
+The easiest way to try out the examples for dynamic provisioning with NFS, is
+to use [Rook Ceph with CephNFS][rook_ceph]. Rook can be used to deploy a Ceph
+cluster. Ceph is able to maintain a NFS-Ganesha service with a few commands,
+making configuring the Ceph cluster a minimal effort.
+
+## Enabling the Ceph NFS-service
+
+Ceph does not enable the NFS-service by default. In order for Rook Ceph to be
+able to configure NFS-exports, the NFS-service needs to be configured first.
+
+In the [Rook Toolbox][rook_toolbox], run the following commands:
+
+```console
+ceph osd pool create nfs-ganesha
+ceph mgr module enable rook
+ceph mgr module enable nfs
+ceph orch set backend rook
+```
+
+## Create a NFS-cluster
+
+In the directory where this `README` is located, there is an example
+`rook-nfs.yaml` file. This file can be used to create a Ceph managed
+NFS-cluster with the name "my-nfs".
+
+```console
+$ kubectl create -f rook-nfs.yaml
+cephnfs.ceph.rook.io/my-nfs created
+```
+
+The CephNFS resource will create a NFS-Ganesha Pod and Service with label
+`app=rook-ceph-nfs`:
+
+```console
+$ kubectl get pods -l app=rook-ceph-nfs
+NAME                                      READY   STATUS    RESTARTS   AGE
+rook-ceph-nfs-my-nfs-a-5d47f66977-sc2rk   2/2     Running   0          61s
+$ kubectl get service -l app=rook-ceph-nfs
+NAME                     TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
+rook-ceph-nfs-my-nfs-a   ClusterIP   172.30.218.195   <none>        2049/TCP   2m58s
+```
+
+## Create a StorageClass
+
+The parameters of the StorageClass reflect mostly what CephFS requires to
+connect to the Ceph cluster. All required options are commented clearly in the
+`storageclass.yaml` file.
+
+In addition to the CephFS parameters, there are:
+
+- `nfsCluster`: name of the Ceph managed NFS-cluster (here `my-nfs`)
+- `server`: hostname/IP/service of the NFS-server (here `172.30.218.195`)
+
+Edit `storageclass.yaml`, and create the resource:
+
+```console
+$ kubectl create -f storageclass.yaml
+storageclass.storage.k8s.io/csi-nfs-sc created
+```
+
+## TODO: next steps
+
+- deploy the NFS-provisioner
+- deploy the kubernetes-csi/csi-driver-nfs
+- create the CSIDriver object
+
+[rook_ceph]: https://rook.io/docs/rook/latest/ceph-nfs-crd.html
+[rook_toolbox]: https://rook.io/docs/rook/latest/ceph-toolbox.html

examples/nfs/rook-nfs.yaml

@@ -0,0 +1,19 @@
+---
+apiVersion: ceph.rook.io/v1
+kind: CephNFS
+metadata:
+  name: my-nfs
+  namespace: default
+spec:
+  # For Ceph v15, the rados block is required. It is ignored for Ceph v16.
+  rados:
+    # Ceph v16 always uses/expects "nfs-ganesha"
+    pool: nfs-ganesha
+    # RADOS namespace where NFS client recovery data is stored in the pool.
+    # fixed value for Ceph v16: the name of this CephNFS object
+    namespace: my-nfs
+
+  # Settings for the NFS server
+  server:
+    # the number of active NFS servers
+    active: 1