Complete Example Using GlusterFS for Dynamic Provisioning

You are viewing documentation for a release that is no longer supported. The latest supported version of version 3 is [3.11]. For the most recent version 4, see [4]

You are viewing documentation for a release that is no longer supported. The latest supported version of version 3 is [3.11]. For the most recent version 4, see [4]

Overview

This topic provides an end-to-end example of how to use an existing Containerized GlusterFS, External GlusterFS, or standalone GlusterFS cluster as dynamic persistent storage for OKD. It is assumed that a working GlusterFS cluster is already set up. For help installing Containerized GlusterFS or External GlusterFS, see Persistent Storage Using GlusterFS.

Prerequisites

To access GlusterFS volumes, the mount.glusterfs command must be available on all schedulable nodes. For RPM-based systems, the glusterfs-fuse package must be installed:

# yum install glusterfs-fuse

If glusterfs-fuse is already installed on the nodes, ensure that the latest version is installed:

# yum update glusterfs-fuse

By default, SELinux does not allow writing from a pod to a remote GlusterFS server. To enable writing to GlusterFS volumes with SELinux on, run the following on each node running GlusterFS:

$ sudo setsebool -P virt_sandbox_use_fusefs on (1)
$ sudo setsebool -P virt_use_fusefs on

Dynamic Provisioning

1. To enable dynamic provisioning, first create a StorageClass object definition. The definition below is based on the minimum requirements needed for this example to work with OKD. See Dynamic Provisioning and Creating Storage Classes for additional parameters and specification definitions.

   kind: StorageClass
   apiVersion: storage.k8s.io/v1
   metadata:
     name: glusterfs
   provisioner: kubernetes.io/glusterfs
   parameters:
     resturl: "http://10.42.0.0:8080" (1)
     restauthenabled: "false" (2)

   1	The heketi server URL.
   2	Since authentication is not turned on in this example, set to false.

2. From the OKD master host, create the StorageClass:

   # oc create -f gluster-storage-class.yaml
   storageclass "glusterfs" created

3. Create a PVC using the newly-created StorageClass. For example:

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: gluster1
   spec:
     accessModes:
     - ReadWriteMany
     resources:
       requests:
         storage: 30Gi
     storageClassName: glusterfs

4. From the OKD master host, create the PVC:

   # oc create -f glusterfs-dyn-pvc.yaml
   persistentvolumeclaim "gluster1" created

5. View the PVC to see that the volume was dynamically created and bound to the PVC:

   # oc get pvc
   NAME       STATUS   VOLUME                                     CAPACITY   ACCESSMODES   STORAGECLASS   AGE
   gluster1   Bound    pvc-78852230-d8e2-11e6-a3fa-0800279cf26f   30Gi       RWX           glusterfs      42s

Using the Storage

At this point, you have a dynamically created GlusterFS volume bound to a PVC. You can now utilize this PVC in a pod.

1. Create the pod object definition:

   apiVersion: v1
   kind: Pod
   metadata:
     name: hello-openshift-pod
     labels:
       name: hello-openshift-pod
   spec:
     containers:
     - name: hello-openshift-pod
       image: openshift/hello-openshift
       ports:
       - name: web
         containerPort: 80
       volumeMounts:
       - name: gluster-vol1
         mountPath: /usr/share/nginx/html
         readOnly: false
     volumes:
     - name: gluster-vol1
       persistentVolumeClaim:
         claimName: gluster1 (1)

   1	The name of the PVC created in the previous step.

2. From the OKD master host, create the pod:

   # oc create -f hello-openshift-pod.yaml
   pod "hello-openshift-pod" created

3. View the pod. Give it a few minutes, as it might need to download the image if it does not already exist:

   # oc get pods -o wide
   NAME                               READY     STATUS    RESTARTS   AGE       IP               NODE
   hello-openshift-pod                          1/1       Running   0          9m        10.38.0.0        node1

4. oc exec into the container and create an index.html file in the mountPath definition of the pod:

   $ oc exec -ti hello-openshift-pod /bin/sh
   $ cd /usr/share/nginx/html
   $ echo 'Hello OpenShift!!!' > index.html
   $ ls
   index.html
   $ exit

5. Now curl the URL of the pod:

   # curl http://10.38.0.0
   Hello OpenShift!!!

6. Delete the pod, recreate it, and wait for it to come up:

   # oc delete pod hello-openshift-pod
   pod "hello-openshift-pod" deleted
   # oc create -f hello-openshift-pod.yaml
   pod "hello-openshift-pod" created
   # oc get pods -o wide
   NAME                               READY     STATUS    RESTARTS   AGE       IP               NODE
   hello-openshift-pod                          1/1       Running   0          9m        10.37.0.0        node1

7. Now curl the pod again and it should still have the same data as before. Note that its IP address may have changed:

   # curl http://10.37.0.0
   Hello OpenShift!!!

8. Check that the index.html file was written to GlusterFS storage by doing the following on any of the nodes:

   $ mount | grep heketi
   /dev/mapper/VolGroup00-LogVol00 on /var/lib/heketi type xfs (rw,relatime,seclabel,attr2,inode64,noquota)
   /dev/mapper/vg_f92e09091f6b20ab12b02a2513e4ed90-brick_1e730a5462c352835055018e1874e578 on /var/lib/heketi/mounts/vg_f92e09091f6b20ab12b02a2513e4ed90/brick_1e730a5462c352835055018e1874e578 type xfs (rw,noatime,seclabel,nouuid,attr2,inode64,logbsize=256k,sunit=512,swidth=512,noquota)
   /dev/mapper/vg_f92e09091f6b20ab12b02a2513e4ed90-brick_d8c06e606ff4cc29ccb9d018c73ee292 on /var/lib/heketi/mounts/vg_f92e09091f6b20ab12b02a2513e4ed90/brick_d8c06e606ff4cc29ccb9d018c73ee292 type xfs (rw,noatime,seclabel,nouuid,attr2,inode64,logbsize=256k,sunit=512,swidth=512,noquota)
   $ cd /var/lib/heketi/mounts/vg_f92e09091f6b20ab12b02a2513e4ed90/brick_d8c06e606ff4cc29ccb9d018c73ee292/brick
   $ ls
   index.html
   $ cat index.html
   Hello OpenShift!!!