Documentation

    PLEASE NOTE: This document applies to v0.8 version and not to the latest release v1.0

    Documentation for other releases can be found by using the version selector in the left bottom of any doc page.

    Block Storage

    Block storage allows you to mount storage to a single pod. This example shows how to build a simple, multi-tier web application on Kubernetes using persistent volumes enabled by Rook.

    Prerequisites

    This guide assumes you have created a Rook cluster as explained in the main Quickstart 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 storageclass.yaml:

    apiVersion: ceph.rook.io/v1beta1
    kind: Pool
    metadata:
      name: replicapool
      namespace: rook-ceph
    spec:
      replicated:
        size: 3
    ---
    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
       name: rook-ceph-block
    provisioner: ceph.rook.io/block
    parameters:
      pool: replicapool
      #The value of "clusterNamespace" MUST be the same as the one in which your rook cluster exist
      clusterNamespace: rook-ceph
    

    Create the storage class.

    kubectl create -f storageclass.yaml
    

    Consume the storage: Wordpress sample

    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 browser:

    $ 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.

    If you are using Minikube, the Wordpress URL can be retrieved with this one-line command:

    echo http://$(minikube ip):$(kubectl get service wordpress -o jsonpath='{.spec.ports[0].nodePort}')
    

    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.

    Consume the storage: Toolbox

    With the pool that was created above, we can also create a block image and mount it directly in a pod. See the Direct Block Tools topic for more details.

    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-ceph pool replicapool
    kubectl delete storageclass rook-ceph-block