Chapter 13. Creating exports using NFS [Technology Preview]

Procedure

1. In the OpenShift Web Console, click Storage Persistent Volume Claims
2. Set the Project to openshift-storage.

3. Click Create PersistentVolumeClaim.

   1. Specify Storage Class, ocs-storagecluster-ceph-nfs.
   2. Specify the PVC Name, for example, my-nfs-export.
   3. Select the required Access Mode.
   4. Specify a Size as per application requirement.

   5. Select Volume mode as Filesystem.

      Note: Block mode is not supported for NFS PVCs

   6. Click Create and wait until the PVC is in Bound status.

Procedure

1. On the OpenShift Container Platform web console, navigate to Workloads Pods.
2. Click Create Pod to create a new application pod.
3. Under the metadata section add a name. For example, nfs-export-example, with namespace as openshift-storage.

4. Under the spec: section, add containers: section with image and volumeMounts sections:

   apiVersion: v1
   kind: Pod
   metadata:
    name: nfs-export-example
    namespace: openshift-storage
   spec:
    containers:
      - name: web-server
        image: nginx
        volumeMounts:
          - name: <volume_name>
            mountPath: /var/lib/www/html

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   For example:

   apiVersion: v1
   kind: Pod
   metadata:
    name: nfs-export-example
    namespace: openshift-storage
   spec:
    containers:
      - name: web-server
        image: nginx
        volumeMounts:
          - name: nfs-export-pvc
            mountPath: /var/lib/www/html

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5. Under the spec: section, add volumes: section to add the NFS PVC as a volume for the application pod:

   volumes:
     - name: <volume_name>
       persistentVolumeClaim:
         claimName: <pvc_name>

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   For example:

   volumes:
     - name: nfs-export-pvc
       persistentVolumeClaim:
         claimName: my-nfs-export

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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

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

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   For example:

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

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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

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

3. Collect connection information. The information external 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

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         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

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      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

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   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 external 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"}]

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4. Connect the external 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

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   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.