k3s/examples/experimental/persistent-volume-provisioning/README.md

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<h2>PLEASE NOTE: This document applies to the HEAD of the source tree</h2>

If you are using a released version of Kubernetes, you should
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<strong>
The latest release of this document can be found
[here](http://releases.k8s.io/release-1.4/examples/experimental/persistent-volume-provisioning/README.md).

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## Persistent Volume Provisioning

This example shows how to use experimental persistent volume provisioning.

### Pre-requisites

This example assumes that you have an understanding of Kubernetes administration and can modify the
scripts that launch kube-controller-manager.

### Admin Configuration

The admin must define `StorageClass` objects that describe named "classes" of storage offered in a cluster. Different classes might map to arbitrary levels or policies determined by the admin. When configuring a `StorageClass` object for persistent volume provisioning, the admin will need to describe the type of provisioner to use and the parameters that will be used by the provisioner when it provisions a `PersistentVolume` belonging to the class.

The name of a StorageClass object is significant, and is how users can request a particular class, by specifying the name in their `PersistentVolumeClaim`. The `provisioner` field must be specified as it determines what volume plugin is used for provisioning PVs. 2 cloud providers will be provided in the beta version of this feature: EBS and GCE. The `parameters` field contains the parameters that describe volumes belonging to the storage class. Different parameters may be accepted depending on the `provisioner`. For example, the value `io1`, for the parameter `type`, and the parameter `iopsPerGB` are specific to EBS . When a parameter is omitted, some default is used.

#### AWS

```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
  name: slow
provisioner: kubernetes.io/aws-ebs
parameters:
  type: io1
  zone: us-east-1d
  iopsPerGB: "10"
```

* `type`: `io1`, `gp2`, `sc1`, `st1`. See AWS docs for details. Default: `gp2`.
* `zone`: AWS zone. If not specified, a random zone from those where Kubernetes cluster has a node is chosen.
* `iopsPerGB`: only for `io1` volumes. I/O operations per second per GiB. AWS volume plugin multiplies this with size of requested volume to compute IOPS of the volume and caps it at 20 000 IOPS (maximum supported by AWS, see AWS docs).
* `encrypted`: denotes whether the EBS volume should be encrypted or not. Valid values are `true` or `false`.
* `kmsKeyId`: optional. The full Amazon Resource Name of the key to use when encrypting the volume. If none is supplied but `encrypted` is true, a key is generated by AWS. See AWS docs for valid ARN value.

#### GCE

```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
  name: slow
provisioner: kubernetes.io/gce-pd
parameters:
  type: pd-standard
  zone: us-central1-a
```

* `type`: `pd-standard` or `pd-ssd`. Default: `pd-ssd`
* `zone`: GCE zone. If not specified, a random zone in the same region as controller-manager will be chosen.

#### GLUSTERFS

```yaml
apiVersion: storage.k8s.io/v1beta1
kind: StorageClass
metadata:
  name: slow
provisioner: kubernetes.io/glusterfs
parameters:
  endpoint: "glusterfs-cluster"
  resturl: "http://127.0.0.1:8081"
  restauthenabled: "true"
  restuser: "admin"
  restuserkey: "password"
```

* `endpoint`: `glusterfs-cluster` is the endpoint name which includes GlusterFS trusted pool IP addresses. This parameter is mandatory. We need to also create a service for this endpoint, so that the endpoint will be persisted. This service can be without a selector to tell Kubernetes we want to add its endpoints manually.  Please note that, glusterfs plugin looks for the endpoint in the pod namespace, so it is mandatory that the endpoint and service have to be created in Pod's namespace for successful mount of gluster volumes in the pod.
* `resturl` : Gluster REST service/Heketi service url which provision gluster volumes on demand. The general format should be `IPaddress:Port` and this is a mandatory parameter for GlusterFS dynamic provisioner. If Heketi service is exposed as a routable service in openshift/kubernetes setup, this can have a format similar to
`http://heketi-storage-project.cloudapps.mystorage.com` where the fqdn is a resolvable heketi service url.
* `restauthenabled` : Gluster REST service authentication boolean is required if the authentication is enabled on the REST server. If this value is 'true', 'restuser' and 'restuserkey' have to be filled.
* `restuser` : Gluster REST service/Heketi user who has access to create volumes in the Gluster Trusted Pool.
* `restuserkey` : Gluster REST service/Heketi user's password which will be used for authentication to the REST server.

Reference : ([How to configure Heketi](https://github.com/heketi/heketi/wiki/Setting-up-the-topology))

Create endpoints

As in example [glusterfs-endpoints.json](../../volumes/glusterfs/glusterfs-endpoints.json) file, the "IP" field should be filled with the address of a node in the Glusterfs server cluster. It is fine to give any valid value (from 1 to 65535) to the "port" field.

Create the endpoints,

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

You can verify that the endpoints are successfully created by running

```sh
$ 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 persisted. It is possible to create `service` without a selector to tell Kubernetes we want to add its endpoints manually. For an example service file refer [glusterfs-service.json](../../volumes/glusterfs/glusterfs-service.json).

Use this command to create the service:

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

#### OpenStack Cinder

```yaml
kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
  name: gold
provisioner: kubernetes.io/cinder
parameters:
  type: fast
  availability: nova
```

* `type`: [VolumeType](http://docs.openstack.org/admin-guide/dashboard-manage-volumes.html) created in Cinder. Default is empty.
* `availability`: Availability Zone. Default is empty.

#### Ceph RBD

```yaml                                                                                                                                                                                                          
  apiVersion: extensions/v1beta1                                                                                                                                                                                   
  kind: StorageClass                                                                                                                                                                                               
  metadata: 
   name: fast
provisioner: kubernetes.io/rbd
parameters:
    monitors: 10.16.153.105:6789
    adminId: kube
    adminSecretName: ceph-secret
    adminSecretNamespace: kube-system
    pool: kube
    userId: kube
    userSecretName: ceph-secret-user
```

* `monitors`: Ceph monitors, comma delimited. It is required.
* `adminId`: Ceph client ID that is capable of creating images in the pool. Default is "admin".
* `adminSecret`: Secret Name for `adminId`. It is required.
* `adminSecretNamespace`: The namespace for `adminSecret`. Default is "default".
* `pool`: Ceph RBD pool. Default is "rbd".
* `userId`: Ceph client ID that is used to map the RBD image. Default is the same as `adminId`.
* `userSecretName`: The name of Ceph Secret for `userId` to map RBD image. It must exist in the same namespace as PVCs. It is required.

### User provisioning requests

Users request dynamically provisioned storage by including a storage class in their `PersistentVolumeClaim`.
The annotation `volume.beta.kubernetes.io/storage-class` is used to access this experimental feature. It is required that this value matches the name of a `StorageClass` configured by the administrator.
In the future, the storage class may remain in an annotation or become a field on the claim itself.

```
{
  "kind": "PersistentVolumeClaim",
  "apiVersion": "v1",
  "metadata": {
    "name": "claim1",
    "annotations": {
        "volume.beta.kubernetes.io/storage-class": "slow"
    }
  },
  "spec": {
    "accessModes": [
      "ReadWriteOnce"
    ],
    "resources": {
      "requests": {
        "storage": "3Gi"
      }
    }
  }
}
```

### Sample output

#### GCE

This example uses GCE but any provisioner would follow the same flow.

First we note there are no Persistent Volumes in the cluster.  After creating a storage class and a claim including that storage class, we see a new PV is created
and automatically bound to the claim requesting storage.


```
$ kubectl get pv

$ kubectl create -f examples/experimental/persistent-volume-provisioning/gce-pd.yaml
storageclass "slow" created

$ kubectl create -f examples/experimental/persistent-volume-provisioning/claim1.json
persistentvolumeclaim "claim1" created

$ kubectl get pv
NAME                                       CAPACITY   ACCESSMODES   STATUS    CLAIM                        REASON    AGE
pvc-bb6d2f0c-534c-11e6-9348-42010af00002   3Gi        RWO           Bound     default/claim1                         4s

$ kubectl get pvc
NAME      LABELS    STATUS    VOLUME                                     CAPACITY   ACCESSMODES   AGE
claim1    <none>    Bound     pvc-bb6d2f0c-534c-11e6-9348-42010af00002   3Gi        RWO           7s

# delete the claim to release the volume
$ kubectl delete pvc claim1
persistentvolumeclaim "claim1" deleted

# the volume is deleted in response to being release of its claim
$ kubectl get pv

```


#### Ceph RBD

First create Ceph admin's Secret in the system namespace. Here the Secret is created in `kube-system`:

```
$ kubectl create -f examples/experimental/persistent-volume-provisioning/rbd/ceph-secret-admin.yaml --namespace=kube-system
```

Then create RBD Storage Class:

```
$ kubectl create -f examples/experimental/persistent-volume-provisioning/rbd/rbd-storage-class.yaml
```

Before creating PVC in user's namespace (e.g. myns), make sure the Ceph user's Secret exists, if not, create the Secret:

```
$ kubectl create -f examples/experimental/persistent-volume-provisioning/rbd/ceph-secret-user.yaml --namespace=myns
```

Now create a PVC in user's namespace (e.g. myns):

```
$ kubectl create -f examples/experimental/persistent-volume-provisioning/claim1.json --namespace=myns
```

Check the PV and PVC are created:

```
$ kubectl describe pvc --namespace=myns
Name:		claim1
Namespace:	myns
Status:		Bound
Volume:		pvc-1cfa23b3-664b-11e6-9eb9-90b11c09520d
Labels:		<none>
Capacity:	3Gi
Access Modes:	RWO
No events.

$ kubectl describe pv
Name:		pvc-1cfa23b3-664b-11e6-9eb9-90b11c09520d
Labels:		<none>
Status:		Bound
Claim:		myns/claim1
Reclaim Policy:	Delete
Access Modes:	RWO
Capacity:	3Gi
Message:	
Source:
    Type:		RBD (a Rados Block Device mount on the host that shares a pod's lifetime)
    CephMonitors:	[10.16.153.105:6789]
    RBDImage:		kubernetes-dynamic-pvc-1cfb1862-664b-11e6-9a5d-90b11c09520d
    FSType:		
    RBDPool:		kube
    RadosUser:		kube
    Keyring:		/etc/ceph/keyring
    SecretRef:		&{ceph-secret-user}
    ReadOnly:		false
No events.
```

Create a Pod to use the PVC:

```
$ kubectl create -f examples/experimental/persistent-volume-provisioning/rbd/pod.yaml --namespace=myns
```


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