Deploying an app on OpenShift Data Foundation

After you install the OpenShift Data Foundation add-on for your Red Hat® OpenShift® on IBM Cloud® cluster, you can use the ODF storage classes to create a persistent volume claim (PVC). Then, refer to the PVC in your deployment so that your app can save and use data from the underlying ODF storage device.

Minimum required permissions: Editor platform access role and the Writer service access role for the cluster in IBM Cloud Kubernetes Service.

Access your Red Hat OpenShift cluster.

List the ODF storage classes. For more information about ODF storage classes, see the Storage class reference.

oc get sc | grep openshift

Example output

NAME                   PROVISIONER            RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
Immediate              true                   9m19s
ocs-storagecluster-ceph-rbd                   openshift-storage.rbd.csi.ceph.com      Delete          Immediate              false                  9m19s
ocs-storagecluster-ceph-rgw                   openshift-storage.ceph.rook.io/bucket   Delete          Immediate              false                  18m
ocs-storagecluster-cephfs                     openshift-storage.cephfs.csi.ceph.com   Delete          Immediate              true                   10m
openshift-storage.noobaa.io                   openshift-storage.noobaa.io/obc         Delete          Immediate              false                  6m32s

Create a PVC that refers to the storage class that you want to use. Save and edit the following PVC configuration file to refer to the storage class that you want to use. If you enabled encryption with Hyper Protect Crypto Services, you can use the storage class ocs-storagecluster-ceph-rbd-encrypted which supports encryption. Example PVC for using the ocs-storagecluster-cephfs storage class.
```
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: odf-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
  storageClassName: ocs-storagecluster-cephfs
```
Create the PVC in your cluster.
```
oc create -f <my-pvc.yaml>
```

Create a YAML configuration file for a pod that mounts the PVC that you created. The following example creates an nginx pod that writes the current date and time to a test.txt file.

apiVersion: v1
kind: Pod
metadata:
  name: app
spec:
  containers:
  - name: app
    image: nginx
    command: ["/bin/sh"]
    args: ["-c", "while true; do echo $(date -u) >> /test/test.txt; sleep 600; done"]
    volumeMounts:
    - name: persistent-storage
      mountPath: /test
  volumes:
  - name: persistent-storage
    persistentVolumeClaim:
      claimName: odf-pvc

Create the pod in your cluster.
```
oc apply -f pod.yaml
```

To verify that the pod is deployed, wait for your app to get into a Running status.

oc get pods

Example output

NAME                                READY   STATUS    RESTARTS   AGE
app                                 1/1     Running   0          2m58s

Verify that the app can write data.

Display the contents of the test.txt file to confirm that your app can write data to your persistent storage.

cat /test/test.txt

Example output

Tue Mar 2 20:09:19 UTC 2021
Tue Mar 2 20:09:25 UTC 2021
Tue Mar 2 20:09:31 UTC 2021
Tue Mar 2 20:09:36 UTC 2021
Tue Mar 2 20:09:42 UTC 2021
Tue Mar 2 20:09:47 UTC 2021

Exit the pod.
```
exit
```