15.4. Consuming NFS exports in OpenShift cluster

Procedure

1. After the nfs flag is enabled, singe-server CephNFS is deployed by Rook. You need to fetch the value of the ceph_nfs field for the nfs-ganesha server to use in the next step:

   $ oc get pods -n openshift-storage | grep rook-ceph-nfs

   $ oc describe pod  <name of the rook-ceph-nfs pod> | grep ceph_nfs

   For example:

   $ oc describe pod rook-ceph-nfs-ocs-storagecluster-cephnfs-a-7bb484b4bf-bbdhs | grep ceph_nfs
     ceph_nfs=my-nfs

2. Expose the NFS server outside of the OpenShift cluster by creating a Kubernetes LoadBalancer Service. The example below creates a LoadBalancer Service and references the NFS server created by OpenShift Data Foundation.

   apiVersion: v1
   kind: Service
   metadata:
    name: rook-ceph-nfs-ocs-storagecluster-cephnfs-load-balancer
    namespace: openshift-storage
   spec:
    ports:
      - name: nfs
        port: 2049
    type: LoadBalancer
    externalTrafficPolicy: Local
    selector:
      app: rook-ceph-nfs
      ceph_nfs: <my-nfs>
      instance: a

   Replace <my-nfs> with the value you got in step 1.

3. Collect connection information. The information NFS clients need to connect to an export comes from the Persistent Volume (PV) created for the PVC, and the status of the LoadBalancer Service created in the previous step.

   1. Get the share path from the PV.

      1. Get the name of the PV associated with the NFS export’s PVC:

         $ oc get pvc <pvc_name> --output jsonpath='{.spec.volumeName}'
         pvc-39c5c467-d9d3-4898-84f7-936ea52fd99d

         Replace <pvc_name> with your own PVC name. For example:

         oc get pvc pvc-39c5c467-d9d3-4898-84f7-936ea52fd99d --output jsonpath='{.spec.volumeName}'
         pvc-39c5c467-d9d3-4898-84f7-936ea52fd99d

      2. Use the PV name obtained previously to get the NFS export’s share path:

         $ oc get pv pvc-39c5c467-d9d3-4898-84f7-936ea52fd99d --output jsonpath='{.spec.csi.volumeAttributes.share}'
         /0001-0011-openshift-storage-0000000000000001-ba9426ab-d61b-11ec-9ffd-0a580a800215

   2. Get an ingress address for the NFS server. A service’s ingress status may have multiple addresses. Choose the one desired to use for NFS clients. In the example below, there is only a single address: the host name ingress-id.somedomain.com.

      $ oc -n openshift-storage get service rook-ceph-nfs-ocs-storagecluster-cephnfs-load-balancer --output jsonpath='{.status.loadBalancer.ingress}'
      [{"hostname":"ingress-id.somedomain.com"}]

4. Connect the NFS client using the share path and ingress address from the previous steps. The following example mounts the export to the client’s directory path /export/mount/path:

   $ mount -t nfs4 -o proto=tcp ingress-id.somedomain.com:/0001-0011-openshift-storage-0000000000000001-ba9426ab-d61b-11ec-9ffd-0a580a800215 /export/mount/path

   If this does not work immediately, it could be that the Kubernetes environment is still taking time to configure the network resources to allow ingress to the NFS server.