PLEASE NOTE: This document applies to the HEAD of the source tree
If you are using a released version of Kubernetes, you should
refer to the docs that go with that version.
Documentation for other releases can be found at
[releases.k8s.io](http://releases.k8s.io).
--
# Dell EMC ScaleIO Volume Plugin for Kubernetes
This document shows how to configure Kubernetes resources to consume storage from volumes hosted on ScaleIO cluster.
## Pre-Requisites
* Kubernetes ver 1.6 or later
* ScaleIO ver 2.0 or later
* A ScaleIO cluster with an API gateway
* ScaleIO SDC binary installed/configured on each Kubernetes node that will consume storage
## ScaleIO Setup
This document assumes you are familiar with ScaleIO and have a cluster ready to go. If you are *not familiar* with ScaleIO, please review *Learn how to setup a 3-node* [ScaleIO cluster on Vagrant](https://github.com/codedellemc/labs/tree/master/setup-scaleio-vagrant) and see *General instructions on* [setting up ScaleIO](https://www.emc.com/products-solutions/trial-software-download/scaleio.htm)
For this demonstration, ensure the following:
- The ScaleIO `SDC` component is installed and properly configured on all Kubernetes nodes where deployed pods will consume ScaleIO-backed volumes.
- You have a configured ScaleIO gateway that is accessible from the Kubernetes nodes.
## Deploy Kubernetes Secret for ScaleIO
The ScaleIO plugin uses a Kubernetes Secret object to store the `username` and `password` credentials.
Kuberenetes requires the secret values to be base64-encoded to simply obfuscate (not encrypt) the clear text as shown below.
```
$> echo -n "siouser" | base64
c2lvdXNlcg==
$> echo -n "sc@l3I0" | base64
c2NAbDNJMA==
```
The previous will generate `base64-encoded` values for the username and password.
Remember to generate the credentials for your own environment and copy them in a secret file similar to the following.
File: [secret.yaml](secret.yaml)
```
apiVersion: v1
kind: Secret
metadata:
name: sio-secret
type: kubernetes.io/scaleio
data:
username: c2lvdXNlcg==
password: c2NAbDNJMA==
```
Notice the name of the secret specified above as `sio-secret`. It will be referred in other YAML files. Next, deploy the secret.
```
$ kubectl create -f ./examples/volumes/scaleio/secret.yaml
```
## Deploying Pods with Persistent Volumes
The example presented in this section shows how the ScaleIO volume plugin can automatically attach, format, and mount an existing ScaleIO volume for pod.
The Kubernetes ScaleIO volume spec supports the following attributes:
| Attribute | Description |
|-----------|-------------|
| gateway | address to a ScaleIO API gateway (required)|
| system | the name of the ScaleIO system (required)|
| protectionDomain| the name of the ScaleIO protection domain (default `default`)|
| storagePool| the name of the volume storage pool (default `default`)|
| storageMode| the storage provision mode: `ThinProvisionned` (default) or `ThickProvisionned`|
| volumeName| the name of an existing volume in ScaleIO (required)|
| secretRef:name| reference to a configuered Secret object (required, see Secret earlier)|
| readOnly| specifies the access mode to the mounted volume (default `false`)|
| fsType| the file system to use for the volume (default `ext4`)|
### Create Volume
Static persistent volumes require that the volume, to be consumed by the pod, be already created in ScaleIO. You can use your ScaleIO tooling to create a new volume or use the name of a volume that already exists in ScaleIO. For this demo, we assume there's a volume named `vol-0`. If you want to use an existing volume, ensure its name is reflected properly in the `volumeName` attribute below.
### Deploy Pod YAML
Create a pod YAML file that declares the volume (above) to be used.
File: [pod.yaml](pod.yaml)
```
apiVersion: v1
kind: Pod
metadata:
name: pod-0
spec:
containers:
- image: gcr.io/google_containers/test-webserver
name: pod-0
volumeMounts:
- mountPath: /test-pd
name: vol-0
volumes:
- name: vol-0
scaleIO:
gateway: https://localhost:443/api
system: scaleio
volumeName: vol-0
secretRef:
name: sio-secret
fsType: xfs
```
Notice the followings in the previous YAML:
- Update the `gatewway` to point to your ScaleIO gateway endpoint.
- The `volumeName` attribute refers to the name of an existing volume in ScaleIO.
- The `secretRef:name` attribute references the name of the secret object deployed earlier.
Next, deploy the pod.
```
$> kubectl create -f examples/volumes/scaleio/pod.yaml
```
You can verify the pod:
```
$> kubectl get pod
NAME READY STATUS RESTARTS AGE
pod-0 1/1 Running 0 33s
```
Or for more detail, use
```
kubectl describe pod pod-0
```
You can see the attached/mapped volume on the node:
```
$> lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
...
scinia 252:0 0 8G 0 disk /var/lib/kubelet/pods/135986c7-dcb7-11e6-9fbf-080027c990a7/volumes/kubernetes.io~scaleio/vol-0
```
## StorageClass and Dynamic Provisioning
In the example in this section, we will see how the ScaleIO volume plugin can automatically provision described in a `StorageClass`.
The ScaleIO volume plugin is a dynamic provisioner identified as `kubernetes.io/scaleio` and supports the following parameters:
| Parameter | Description |
|-----------|-------------|
| gateway | address to a ScaleIO API gateway (required)|
| system | the name of the ScaleIO system (required)|
| protectionDomain| the name of the ScaleIO protection domain (default `default`)|
| storagePool| the name of the volume storage pool (default `default`)|
| storageMode| the storage provision mode: `ThinProvisionned` (default) or `ThickProvisionned`|
| secretRef| reference to the name of a configuered Secret object (required)|
| readOnly| specifies the access mode to the mounted volume (default `false`)|
| fsType| the file system to use for the volume (default `ext4`)|
### ScaleIO StorageClass
Define a new `StorageClass` as shown in the following YAML.
File [sc.yaml](sc.yaml)
```
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: sio-small
provisioner: kubernetes.io/scaleio
parameters:
gateway: https://localhost:443/api
system: scaleio
protectionDomain: default
secretRef: sio-secret
fsType: xfs
```
Note the followings:
- The `name` attribute is set to sio-small . It will be referenced later.
- The `secretRef` attribute matches the name of the Secret object created earlier.
Next, deploy the storage class file.
```
$> kubectl create -f examples/volumes/scaleio/sc.yaml
$> kubectl get sc
NAME TYPE
sio-small kubernetes.io/scaleio
```
### PVC for the StorageClass
The next step is to define/deploy a `PeristentVolumeClaim` that will use the StorageClass.
File [sc-pvc.yaml](sc-pvc.yaml)
```
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: pvc-sio-small
annotations:
volume.beta.kubernetes.io/storage-class: sio-small
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
```
Note the `annotations:` entry which specifies annotation `volume.beta.kubernetes.io/storage-class: sio-small` which references the name of the storage class defined earlier.
Next, we deploy PVC file for the storage class. This step will cause the Kubernetes ScaleIO plugin to create the volume in the storage system.
```
$> kubectl create -f examples/volumes/scaleio/sc-pvc.yaml
```
You verify that a new volume created in the ScaleIO dashboard. You can also verify the newly created volume as follows.
```
kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESSMODES AGE
pvc-sio-small Bound pvc-5fc78518-dcae-11e6-a263-080027c990a7 10Gi RWO 1h
```
###Pod for PVC and SC
At this point, the volume is created (by the claim) in the storage system. To use it, we must define a pod that references the volume as done in this YAML.
File [pod-sc-pvc.yaml](pod-sc-pvc.yaml)
```
kind: Pod
apiVersion: v1
metadata:
name: pod-sio-small
spec:
containers:
- name: pod-sio-small-container
image: gcr.io/google_containers/test-webserver
volumeMounts:
- mountPath: /test
name: test-data
volumes:
- name: test-data
persistentVolumeClaim:
claimName: pvc-sio-small
```
Notice that the `claimName:` attribute refers to the name of the PVC defined and deployed earlier. Next, let us deploy the file.
```
$> kubectl create -f examples/volumes/scaleio/pod-sc-pvc.yaml
```
We can now verify that the new pod is deployed OK.
```
kubectl get pod
NAME READY STATUS RESTARTS AGE
pod-0 1/1 Running 0 23m
pod-sio-small 1/1 Running 0 5s
```
You can use the ScaleIO dashboard to verify that the new volume has one attachment. You can verify the volume information for the pod:
```
$> kubectl describe pod pod-sio-small
...
Volumes:
test-data:
Type: PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
ClaimName: pvc-sio-small
ReadOnly: false
...
```
Lastly, you can see the volume's attachment on the Kubernetes node:
```
$> lsblk
...
scinia 252:0 0 8G 0 disk /var/lib/kubelet/pods/135986c7-dcb7-11e6-9fbf-080027c990a7/volumes/kubernetes.io~scaleio/vol-0
scinib 252:16 0 16G 0 disk /var/lib/kubelet/pods/62db442e-dcba-11e6-9fbf-080027c990a7/volumes/kubernetes.io~scaleio/sio-5fc9154ddcae11e68db708002
```
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