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c38c260 Nov 13, 2016
@thockin @joe2far @humblec @david-mcmahon @ciwang
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Glusterfs

Glusterfs is an open source scale-out filesystem. These examples provide information about how to allow containers use Glusterfs volumes.

The example assumes that you have already set up a Glusterfs server cluster and the Glusterfs client package is installed on all Kubernetes nodes.

Prerequisites

Set up Glusterfs server cluster; install Glusterfs client package on the Kubernetes nodes. (Guide)

Create endpoints

Here is a snippet of glusterfs-endpoints.json,

      "addresses": [
        {
          "IP": "10.240.106.152"
        }
      ],
      "ports": [
        {
          "port": 1
        }
      ]

The "IP" field should be filled with the address of a node in the Glusterfs server cluster. In this example, it is fine to give any valid value (from 1 to 65535) to the "port" field.

Create the endpoints,

$ kubectl create -f examples/volumes/glusterfs/glusterfs-endpoints.json

You can verify that the endpoints are successfully created by running

$ kubectl get endpoints
NAME                ENDPOINTS
glusterfs-cluster   10.240.106.152:1,10.240.79.157:1

We need also create a service for this endpoints, so that the endpoints will be persistented. We will add this service without a selector to tell Kubernetes we want to add its endpoints manually. You can see glusterfs-service.json for details.

Use this command to create the service:

$ kubectl create -f examples/volumes/glusterfs/glusterfs-service.json

Create a POD

The following volume spec in glusterfs-pod.json illustrates a sample configuration.

{
     "name": "glusterfsvol",
     "glusterfs": {
        "endpoints": "glusterfs-cluster",
        "path": "kube_vol",
        "readOnly": true
    }
}

The parameters are explained as the followings.

  • endpoints is endpoints name that represents a Gluster cluster configuration. kubelet is optimized to avoid mount storm, it will randomly pick one from the endpoints to mount. If this host is unresponsive, the next Gluster host in the endpoints is automatically selected.
  • path is the Glusterfs volume name.
  • readOnly is the boolean that sets the mountpoint readOnly or readWrite.

Create a pod that has a container using Glusterfs volume,

$ kubectl create -f examples/volumes/glusterfs/glusterfs-pod.json

You can verify that the pod is running:

$ kubectl get pods
NAME             READY     STATUS    RESTARTS   AGE
glusterfs        1/1       Running   0          3m

$ kubectl get pods glusterfs -t '{{.status.hostIP}}{{"\n"}}'
10.240.169.172

You may ssh to the host (the hostIP) and run 'mount' to see if the Glusterfs volume is mounted,

$ mount | grep kube_vol
10.240.106.152:kube_vol on /var/lib/kubelet/pods/f164a571-fa68-11e4-ad5c-42010af019b7/volumes/kubernetes.io~glusterfs/glusterfsvol type fuse.glusterfs (rw,relatime,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072)

You may also run docker ps on the host to see the actual container.

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