add rados block device(rbd) volume plugin

Signed-off-by: Huamin Chen <hchen@redhat.com>

examples/examples_test.go

@@ -178,6 +178,10 @@ func TestExampleObjectSchemas(t *testing.T) {
 			"pod":         &api.Pod{},
 			"replication": &api.ReplicationController{},
 		},
+		"../examples/rbd/v1beta3": {
+			"rbd":             &api.Pod{},
+			"rbd-with-secret": &api.Pod{},
+		},
 	}
 
 	for path, expected := range cases {

examples/rbd/README.md

@@ -0,0 +1,48 @@
+# How to Use it?
+Install Ceph on the Kubernetes host. For example, on Fedora 21
+
+    # yum -y install ceph
+   
+If you don't have a Ceph cluster, you can set up a [containerized Ceph cluster](https://github.com/rootfs/docker-ceph)
+   
+Then get the keyring from the Ceph cluster and copy it to */etc/ceph/keyring*.
+
+Once you have installed Ceph and new Kubernetes, you can create a pod based on my examples [rbd.json](v1beta3/rbd.json)  [rbd-with-secret.json](v1beta3/rbd-with-secret.json). In the pod JSON, you need to provide the following information.
+
+- *monitors*:  Ceph monitors.
+- *pool*: The name of the RADOS pool, if not provided, default *rbd* pool is used.
+- *image*: The image name that rbd has created. 
+- *user*: The RADOS user name. If not provided, default *admin* is used.
+- *keyring*: The path to the keyring file. If not provided, default */etc/ceph/keyring* is used.
+- *secretName*: The name of the authentication secrets. If provided, *secretName* overrides *keyring*. Note, see below about how to create a secret.
+- *fsType*: The filesystem type (ext4, xfs, etc) that formatted on the device.
+- *readOnly*: Whether the filesystem is used as readOnly.
+
+# Use Ceph Authentication Secret
+
+If Ceph authentication secret is provided, the secret should be first be base64 encoded, then encoded string is placed in a secret yaml. An example yaml is provided [here](secret/ceph-secret.yaml). Then post the secret through ```kubectl``` in the following command.
+
+```console
+    # cluster/kubectl.sh create -f examples/rbd/secret/ceph-secret.yaml
+```	
+
+# Get started
+
+Here are my commands:
+
+```console
+    # cluster/kubectl.sh create -f examples/rbd/v1beta3/rbd.json
+    # cluster/kubectl.sh get pods
+```
+
+On the Kubernetes host, I got these in mount output
+
+```console
+    #mount |grep kub
+	/dev/rbd0 on /var/lib/kubelet/plugins/kubernetes.io/rbd/rbd/kube-image-foo type ext4 (ro,relatime,stripe=4096,data=ordered)
+	/dev/rbd0 on /var/lib/kubelet/pods/ec2166b4-de07-11e4-aaf5-d4bed9b39058/volumes/kubernetes.io~rbd/rbdpd type ext4 (ro,relatime,stripe=4096,data=ordered)
+```
+
+ If you ssh to that machine, you can run `docker ps` to see the actual pod and `docker inspect` to see the volumes used by the container.
+
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/examples/rbd/README.md?pixel)]()

examples/rbd/secret/ceph-secret.yaml

@@ -0,0 +1,6 @@
+apiVersion: v1beta3
+kind: Secret
+metadata:
+  name: ceph-secret
+data:
+  key: QVFCMTZWMVZvRjVtRXhBQTVrQ1FzN2JCajhWVUxSdzI2Qzg0SEE9PQ==

examples/rbd/v1beta3/rbd-with-secret.json

@@ -0,0 +1,42 @@
+{
+    "apiVersion": "v1beta3",
+    "id": "rbdpd2",
+    "kind": "Pod",
+    "metadata": {
+        "name": "rbd2"
+    },
+    "spec": {
+        "containers": [
+            {
+                "name": "rbd-rw",
+                "image": "kubernetes/pause",
+                "volumeMounts": [
+                    {
+                        "mountPath": "/mnt/rbd",
+                        "name": "rbdpd"
+                    }
+                ]
+            }
+        ],
+        "volumes": [
+            {
+                "name": "rbdpd",
+                "rbd": {
+                    "monitors": [
+        						"10.16.154.78:6789",
+						        "10.16.154.82:6789",
+        						"10.16.154.83:6789"
+    				 ],
+                    "pool": "kube",
+                    "image": "foo",
+                    "user": "admin",
+                    "secretRef": {
+						  "name": "ceph-secret"
+					 },
+                    "fsType": "ext4",
+                    "readOnly": true
+                }
+            }
+        ]
+    }
+}

examples/rbd/v1beta3/rbd.json

@@ -0,0 +1,40 @@
+{
+    "apiVersion": "v1beta3",
+    "id": "rbdpd",
+    "kind": "Pod",
+    "metadata": {
+        "name": "rbd"
+    },
+    "spec": {
+        "containers": [
+            {
+                "name": "rbd-rw",
+                "image": "kubernetes/pause",
+                "volumeMounts": [
+                    {
+                        "mountPath": "/mnt/rbd",
+                        "name": "rbdpd"
+                    }
+                ]
+            }
+        ],
+        "volumes": [
+            {
+                "name": "rbdpd",
+                "rbd": {
+                    "monitors": [
+        						"10.16.154.78:6789",
+						        "10.16.154.82:6789",
+        						"10.16.154.83:6789"
+    				 ],
+                    "pool": "kube",
+                    "image": "foo",
+                    "user": "admin",
+                    "keyring": "/etc/ceph/keyring",
+                    "fsType": "ext4",
+                    "readOnly": true
+                }
+            }
+        ]
+    }
+}