Chapter 14. Creating exports using NFS
This section describes how to create exports using NFS that can then be accessed externally from the OpenShift cluster.
Follow the instructions below to create exports and access them externally from the OpenShift Cluster:
14.1. Enabling the NFS feature
To use NFS feature, you need to enable it in the storage cluster using the command-line interface (CLI) after the cluster is created. You can also enable the NFS feature while creating the storage cluster using the user interface.
Prerequisites
- OpenShift Data Foundation is installed and running in the openshift-storage namespace.
- The OpenShift Data Foundation installation includes a CephFilesystem.
Procedure
- Run the following command to enable the NFS feature from CLI:
$ oc --namespace openshift-storage patch storageclusters.ocs.openshift.io ocs-storagecluster --type merge --patch '{"spec": {"nfs":{"enable": true}}}'
Verification steps
NFS installation and configuration is complete when the following conditions are met:
-
The CephNFS resource named
ocs-storagecluster-cephnfs
has a status of Ready. Check if all the
csi-nfsplugin-*
pods are running:oc -n openshift-storage describe cephnfs ocs-storagecluster-cephnfs
oc -n openshift-storage get pod | grep csi-nfsplugin
Output has multiple pods. For example:
csi-nfsplugin-47qwq 2/2 Running 0 10s csi-nfsplugin-77947 2/2 Running 0 10s csi-nfsplugin-ct2pm 2/2 Running 0 10s csi-nfsplugin-provisioner-f85b75fbb-2rm2w 2/2 Running 0 10s csi-nfsplugin-provisioner-f85b75fbb-8nj5h 2/2 Running 0 10s
14.2. Creating NFS exports
NFS exports are created by creating a Persistent Volume Claim (PVC) against the ocs-storagecluster-ceph-nfs
StorageClass.
You can create NFS PVCs two ways:
Create NFS PVC using a yaml.
The following is an example PVC.
volumeMode: Block
will not work for NFS volumes.
apiVersion: v1 kind: PersistentVolumeClaim metadata: name: <desired_name> spec: accessModes: - ReadWriteOnce resources: requests: storage: 1Gi storageClassName: ocs-storagecluster-ceph-nfs
- <desired_name>
-
Specify a name for the PVC, for example,
my-nfs-export
.
The export is created once the PVC reaches the Bound
state.
Create NFS PVCs from the OpenShift Container Platform web console.
Prerequisites
- Ensure that you are logged into the OpenShift Container Platform web console and the NFS feature is enabled for the storage cluster.
Procedure
-
In the OpenShift Web Console, click Storage
Persistent Volume Claims - Set the Project to openshift-storage.
Click Create PersistentVolumeClaim.
-
Specify Storage Class,
ocs-storagecluster-ceph-nfs
. -
Specify the PVC Name, for example,
my-nfs-export
. - Select the required Access Mode.
- Specify a Size as per application requirement.
Select Volume mode as
Filesystem
.Note:
Block
mode is not supported for NFS PVCs-
Click Create and wait until the PVC is in
Bound
status.
-
Specify Storage Class,
14.3. Consuming NFS exports in-cluster
Kubernetes application pods can consume NFS exports created by mounting a previously created PVC.
You can mount the PVC one of two ways:
Using a YAML:
Below is an example pod that uses the example PVC created in Section 14.2, “Creating NFS exports”:
apiVersion: v1 kind: Pod metadata: name: nfs-export-example spec: containers: - name: web-server image: nginx volumeMounts: - name: nfs-export-pvc mountPath: /var/lib/www/html volumes: - name: nfs-export-pvc persistentVolumeClaim: claimName: <pvc_name> readOnly: false
- <pvc_name>
-
Specify the PVC you have previously created, for example,
my-nfs-export
.
Using the OpenShift Container Platform web console.
Procedure
-
On the OpenShift Container Platform web console, navigate to Workloads
Pods. - Click Create Pod to create a new application pod.
- Under the metadata section add a name. For example, nfs-export-example, with namespace as openshift-storage.
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
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
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>
For example:
volumes: - name: nfs-export-pvc persistentVolumeClaim: claimName: my-nfs-export
14.4. Consuming NFS exports externally from the OpenShift cluster
NFS clients outside of the OpenShift cluster can mount NFS exports created by a previously-created PVC.
Procedure
After the
nfs
flag is enabled, singe-server CephNFS is deployed by Rook. You need to fetch the value of theceph_nfs
field for thenfs-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
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.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.
Get the share path from the PV.
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
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
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"}]
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
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.