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Provisioning documentation updates
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@jsafrane
jsafrane committed Aug 18, 2016
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20 changes: 10 additions & 10 deletions docs/proposals/volume-provisioning.md
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Expand Up @@ -122,13 +122,13 @@ We propose that:
a match is found. The claim is `Pending` during this period.

4. With StorageClass instance, the controller finds volume plugin specified by
StorageClass.ProvisionerType.
StorageClass.Provisioner.

5. All provisioners are in-tree; they implement an interface called
`ProvisionableVolumePlugin`, which has a method called `NewProvisioner`
that returns a new provisioner.

6. The controller calls volume plugin `Provision` with ProvisionerParameters from the `StorageClass` configuration object.
6. The controller calls volume plugin `Provision` with Parameters from the `StorageClass` configuration object.

7. If `Provision` returns an error, the controller generates an event on the
claim and goes back to step 1., i.e. it will retry provisioning periodically
Expand Down Expand Up @@ -166,11 +166,11 @@ type StorageClass struct {
unversioned.TypeMeta `json:",inline"`
ObjectMeta `json:"metadata,omitempty"`

// ProvisionerType indicates the type of the provisioner.
ProvisionerType string `json:"provisionerType,omitempty"`
// Provisioner indicates the type of the provisioner.
Provisioner string `json:"provisioner,omitempty"`

// Parameters for dynamic volume provisioner.
ProvisionerParameters map[string]string `json:"provisionerParameters,omitempty"`
Parameters map[string]string `json:"parameters,omitempty"`
}

```
Expand Down Expand Up @@ -207,7 +207,7 @@ With the scheme outlined above the provisioner creates PVs using parameters spec
### Provisioner interface changes

`struct volume.VolumeOptions` (containing parameters for a provisioner plugin)
will be extended to contain StorageClass.ProvisionerParameters.
will be extended to contain StorageClass.Parameters.

The existing provisioner implementations will be modified to accept the StorageClass configuration object.

Expand All @@ -229,8 +229,8 @@ apiVersion: v1
kind: StorageClass
metadata:
name: aws-fast
provisionerType: kubernetes.io/aws-ebs
provisionerParameters:
provisioner: kubernetes.io/aws-ebs
parameters:
zone: us-east-1b
type: ssd
Expand All @@ -239,8 +239,8 @@ apiVersion: v1
kind: StorageClass
metadata:
name: aws-slow
provisionerType: kubernetes.io/aws-ebs
provisionerParameters:
provisioner: kubernetes.io/aws-ebs
parameters:
zone: us-east-1b
type: spinning
```
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79 changes: 48 additions & 31 deletions examples/experimental/persistent-volume-provisioning/README.md
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Expand Up @@ -43,34 +43,49 @@ scripts that launch kube-controller-manager.

### Admin Configuration

No configuration is required by the admin! 3 cloud providers will be provided in the alpha version
of this feature: EBS, GCE, and Cinder.

When Kubernetes is running in one of those clouds, there will be an implied provisioner.
There is no provisioner when running outside of any of those 3 cloud providers.

A fourth provisioner is included for testing and development only. It creates HostPath volumes,
which will never work outside of a single node cluster. It is not supported in any way except for
local for testing and development. This provisioner may be used by passing
`--enable-hostpath-provisioner=true` to the controller manager while bringing it up.
When using the `hack/local_up_cluster.sh` script, this flag is turned off by default.
It may be turned on by setting the environment variable `ENABLE_HOSTPATH_PROVISIONER`
to true prior to running the script.

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: extensions/v1beta1
metadata:
name: slow
provisioner: kubernetes.io/aws-ebs
parameters:
type: io1
zone: us-east-1d
iopsPerGB: "10"
```
env ENABLE_HOSTPATH_PROVISIONER=true hack/local-up-cluster.sh
* `type`: `io1`, `gp2`, `sc1`, `st1`. See AWS docs for details. Default: `gp2`.
* `zone`: AWS zone. If not specified, a random zone in the same region as controller-manager will be 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).

#### GCE

```yaml
kind: StorageClass
apiVersion: extensions/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.

### User provisioning requests

Users request dynamically provisioned storage by including a storage class in their `PersistentVolumeClaim`.
The annotation `volume.alpha.kubernetes.io/storage-class` is used to access this experimental feature.
In the future, admins will be able to define many storage classes.
The storage class may remain in an annotation or become a field on the claim itself.

> The value of the storage-class annotation does not matter in the alpha version of this feature. There is
a single implied provisioner per cloud (which creates 1 kind of volume in the provider). The full version of the feature
will require that this value matches what is configured by the administrator.
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.

```
{
Expand All @@ -79,7 +94,7 @@ will require that this value matches what is configured by the administrator.
"metadata": {
"name": "claim1",
"annotations": {
"volume.alpha.kubernetes.io/storage-class": "foo"
"volume.beta.kubernetes.io/storage-class": "slow"
}
},
"spec": {
Expand All @@ -97,26 +112,28 @@ will require that this value matches what is configured by the administrator.
### Sample output
This example uses HostPath but any provisioner would follow the same flow.
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 claim, we see a new PV is created
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
I1012 13:07:57.666759 22875 decoder.go:141] decoding stream as JSON
persistentvolumeclaim "claim1" created

$ kubectl get pv
NAME LABELS CAPACITY ACCESSMODES STATUS CLAIM REASON AGE
pv-hostpath-r6z5o createdby=hostpath-dynamic-provisioner 3Gi RWO Bound default/claim1 2s
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 pv-hostpath-r6z5o 3Gi RWO 7s
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
Expand Down
9 changes: 9 additions & 0 deletions examples/experimental/persistent-volume-provisioning/aws-ebs.yaml
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@@ -0,0 +1,9 @@
kind: StorageClass
apiVersion: extensions/v1beta1
metadata:
name: slow
provisioner: kubernetes.io/aws-ebs
parameters:
type: io1
zone: us-east-1d
iopsPerGB: "10"
2 changes: 1 addition & 1 deletion examples/experimental/persistent-volume-provisioning/claim1.json
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Expand Up @@ -4,7 +4,7 @@
"metadata": {
"name": "claim1",
"annotations": {
"volume.alpha.kubernetes.io/storage-class": "foo"
"volume.beta.kubernetes.io/storage-class": "slow"
}
},
"spec": {
Expand Down
20 changes: 0 additions & 20 deletions examples/experimental/persistent-volume-provisioning/claim2.json
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8 changes: 8 additions & 0 deletions examples/experimental/persistent-volume-provisioning/gce-pd.yaml
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@@ -0,0 +1,8 @@
kind: StorageClass
apiVersion: extensions/v1beta1
metadata:
name: slow
provisioner: kubernetes.io/gce-pd
parameters:
type: pd-standard
zone: us-central1-a

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