Block Storage Quickstart

Block storage allows you to mount storage to a single pod.

Prerequisites

This guide assumes you have created a Rook cluster as explained in the main Kubernetes guide

Provision Storage

Before Rook can start provisioning storage, a StorageClass and its storage pool need to be created. This is needed for Kubernetes to interoperate with Rook for provisioning persistent volumes. For more options on pools, see the documentation on creating storage pools.

Save this storage class definition as rook-storageclass.yaml:

apiVersion: rook.io/v1alpha1
kind: Pool
metadata:
  name: replicapool
  namespace: rook
spec:
  replication:
    size: 1
---
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
   name: rook-block
provisioner: rook.io/block
parameters:
  pool: replicapool

Create the storage class.

kubectl create -f rook-storageclass.yaml

Secrets

The pod consuming storage will need access to a secret for the rbd plugin. The secret is automatically generated in the default namespace, but would need to be copied to other namespaces. In this example we are copying to the kube-system namespace.

kubectl get secret rook-rook-user -o json | jq '.metadata.namespace = "kube-system"' | kubectl apply -f -

Consume the storage

We create a sample app to consume the block storage provisioned by Rook with the classic wordpress and mysql apps. Both of these apps will make use of block volumes provisioned by Rook.

Start mysql and wordpress from the cluster/examples/kubernetes folder:

kubectl create -f mysql.yaml
kubectl create -f wordpress.yaml

Both of these apps create a block volume and mount it to their respective pod. You can see the Kubernetes volume claims by running the following:

$ kubectl get pvc
NAME             STATUS    VOLUME                                     CAPACITY   ACCESSMODES   AGE
mysql-pv-claim   Bound     pvc-95402dbc-efc0-11e6-bc9a-0cc47a3459ee   20Gi       RWO           1m
wp-pv-claim      Bound     pvc-39e43169-efc1-11e6-bc9a-0cc47a3459ee   20Gi       RWO           1m

Once the wordpress and mysql pods are in the Running state, get the cluster IP of the wordpress app and enter it in your brower:

$ kubectl get svc wordpress
NAME        CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
wordpress   10.3.0.155   <pending>     80:30841/TCP   2m

You should see the wordpress app running.

NOTE: When running in a vagrant environment, there will be no external IP address to reach wordpress with. You will only be able to reach wordpress via the CLUSTER-IP from inside the Kubernetes cluster.

Teardown

To clean up all the artifacts created by the block demo:

kubectl delete -f wordpress.yaml
kubectl delete -f mysql.yaml
kubectl delete -n rook pool replicapool
kubectl delete storageclass rook-block