Provision a static local volume

The localvolumeprovisioner component uses the local volume static provisioner to manage persistent volumes for pre-allocated disks. It does this by watching the /mnt/disks folder on each host and creating persistent volumes in the localvolumeprovisioner storage class for each disk that it discovers in this folder.

• Persistent volumes with a ‘Filesystem’ volume-mode are discovered if you mount them under /mnt/disks.

• Persistent volumes with a ‘Block’ volume-mode are discovered if you create a symbolic link to the block device in /mnt/disks.

Before you begin

Before starting this tutorial, verify the following:

• You have access to a Linux, macOS, or Windows computer with a supported operating system version.

• You have a provisioned dkp cluster that uses the localvolumeprovisioner platform application, but have not added any other Kommander applications to the cluster yet.

For this tutorial, you do not deploy using all the default settings as described in the Quick start guide.

This distinction between provisioning and deployment is important because some applications depend on the storage class provided by the localvolumeprovisioner component and can fail to start if it is not configured yet.

Provision the cluster and a volume

1. Create a pre-provisioned cluster by following the steps outlined in the choose pre-provisioned infrastructure topic.

   As volumes are created/mounted on the nodes, the local volume provisioner detects each volume in the /mnt/disks directory and adds it as a persistent volume with the localvolumeprovisioner storage class.

2. Create at least one volume in /mnt/disks on each host.

   For example, mount a tmpfs volume:

   mkdir -p /mnt/disks/example-volume && mount -t tmpfs example-volume /mnt/disks/example-volume
   

3. Verify the persistent volume by running the following command:

   kubectl get pv
   

   The command displays output similar to the following:

   NAME                CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS             REASON   AGE
   local-pv-4c7fc8ba   3986Mi     RWO            Delete           Available           localvolumeprovisioner            2s
   

4. Claim the persistent volume using a PersistentVolumeClaim, by running the following command:

   cat <<EOF | kubectl create -f -
   kind: PersistentVolumeClaim
   apiVersion: v1
   metadata:
     name: example-claim
   spec:
     accessModes:
     - ReadWriteOnce
     resources:
       requests:
         storage: 100Mi
     storageClassName: localvolumeprovisioner
   EOF
   

5. Reference the persistent volume claim in a pod by running the following command:

   cat <<EOF | kubectl create -f -
   apiVersion: v1
   kind: Pod
   metadata:
     name: pod-with-persistent-volume
   spec:
     containers:
       - name: frontend
         image: nginx
         volumeMounts:
           - name: data
             mountPath: "/var/www/html"
     volumes:
       - name: data
         persistentVolumeClaim:
           claimName: example-claim
   EOF
   

6. Verify the persistent volume claim by running the following command:

   kubectl get pvc
   

   The command displays output similar to the following:

   NAME            STATUS   VOLUME              CAPACITY   ACCESS MODES   STORAGECLASS             AGE
   example-claim   Bound    local-pv-4c7fc8ba   3986Mi     RWO            localvolumeprovisioner   78s
   

   NAME                CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                   STORAGECLASS             REASON   AGE
   local-pv-4c7fc8ba   3986Mi     RWO            Delete           Bound       default/example-claim   localvolumeprovisioner            15m
   

Upon deletion of the persistent volume claim, the corresponding persistent volume resource uses the “Delete” reclaim policy, which removes all data on the volume.