StorageOS Volume Guide
As a simple first use of StorageOS with OpenShift following the example below will create a PersistentVolumeClaim (PVC) and schedule a Pod to mount the PersistentVolume (PV) provisioned by the PVC.
Creating the PersistentVolumeClaim
- You can find the latest files in the StorageOS example deployment repository
git clone https://github.com/storageos/deploy.git storageos
apiVersion: v1 kind: PersistentVolumeClaim metadata: name: my-vol-1 annotations: volume.beta.kubernetes.io/storage-class: fast spec: accessModes: - ReadWriteOnce resources: requests: storage: 5Gi
The above PVC will dynamically provision a 5GB volume using the fast StorageClass. This StorageClass was created during the StorageOS install and causes StorageOS to provision a PersistentVolume.
apiVersion: v1 kind: PersistentVolumeClaim metadata: name: my-vol-1 labels: storageos.com/replicas: "1" annotations: volume.beta.kubernetes.io/storage-class: fast spec: accessModes: - ReadWriteOnce resources: requests: storage: 5Gi
The above PVC has the
storageos.com/replicaslabel set. This label tells StorageOS to create a replica for the volume that is created. For the sake of keeping this example simple the unreplicated volume will be used.
- Move into the examples folder and create a PVC using the PVC definition above.
$ cd storageos $ oc create -f ./k8s/examples/pvc.yaml
You can view the PVC that you have created with the command below
$ oc get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE my-vol-1 Bound pvc-f8ffa027-e821-11e8-bc0b-0ac77ccc61fa 5Gi RWO fast 1m
Create a pod that mounts the PVC created in step 2.
$ oc create -f ./k8s/examples/debian-pvc.yaml
The command above creates a Pod that uses the PVC that was created in step 1.
apiVersion: v1 kind: Pod metadata: name: d1 spec: containers: - name: debian image: debian:9-slim command: ["/bin/sleep"] args: [ "3600" ] volumeMounts: - mountPath: /mnt name: v1 volumes: - name: v1 persistentVolumeClaim: claimName: my-vol-1
In the Pod definition above the volume v1, which references the PVC created in step 2, is mounted in the pod at /mnt. In this example a debian image is used for the container but any container image with a shell would work for this example.
- Confirm that the pod is up and running
$ oc get pods NAME READY STATUS RESTARTS AGE d1 1/1 Running 0 1m
- Execute a shell inside the container and write some contents to a file
By writing to /mnt inside the container, the StorageOS volume created by the PVC is being written to. If you were to kill the pod and start it again on a new node, the helloworld file would still be avaliable.