Provision a Static Local Volume

Learn how to provision a static local volume for a DKP cluster

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

Create a pre-provisioned cluster by following the steps outlined in the 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.

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

For example, mount a tmpfs volume:

CODE

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

Verify the persistent volume by running the following command:

CODE

kubectl get pv

The command displays output similar to the following:

CODE

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

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

CODE

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

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

CODE

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

Verify the persistent volume claim by running the following command:

CODE

kubectl get pvc

The command displays output similar to the following:

CODE

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

CODE

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.