Add docs for implementing resize (#5528)

* Add docs for implementing resize * Update admission-controllers.md * Added link to PVC section * minor typo fixes
2017-09-25 16:14:11 -04:00
parent f379efa3b4
commit 6ff373e1d9
2 changed files with 64 additions and 1 deletions
@@ -280,7 +280,7 @@ namespace.  In order to enforce integrity of that process, we strongly recommend
 ### NodeRestriction

 This plug-in limits the `Node` and `Pod` objects a kubelet can modify. In order to be limited by this admission plugin,
-kubelets must use credentials in the `system:nodes` group, with a username in the form `system:node:<nodeName>`. 
+kubelets must use credentials in the `system:nodes` group, with a username in the form `system:node:<nodeName>`.
 Such kubelets will only be allowed to modify their own `Node` API object, and only modify `Pod` API objects that are bound to their node.
 Future versions may add additional restrictions to ensure kubelets have the minimal set of permissions required to operate correctly.

@@ -332,6 +332,35 @@ metadata:
  name: namespace3
 ```

+### PersistentVolumeClaimResize
+
+This plug-in implements additional validations for checking incoming `PersistentVolumeClaim` resize requests.
+**Note:** Support for volume resizing is available as an alpha feature. Admins must set the feature gate `ExpandPersistentVolumes`
+to `true` to enable resizing.
+{: .note}
+
+After enabling the `ExpandPersistentVolumes` feature gate, enabling the `PersistentVolumeClaimResize` admission
+plug-in is recommended, too. This plug-in prevents resizing of all claims by default unless a claim's `StorageClass`
+ explicitly enables resizing by setting `allowVolumeExpansion` to `true`.
+
+For example: all `PersistnetVolumeClaim`s created from the following `StorageClass` support volume expansion:
+
+```yaml
+kind: StorageClass
+apiVersion: storage.k8s.io/v1
+metadata:
+  name: gluster-vol-default
+provisioner: kubernetes.io/glusterfs
+parameters:
+  resturl: "http://192.168.10.100:8080"
+  restuser: ""
+  secretNamespace: ""
+  secretName: ""
+allowVolumeExpansion: true
+```
+
+For more information about persistent volume claims, see ["PersistentVolumeClaims"](/docs/concepts/storage/persistent-volumes/#persistentvolumeclaims).
+
 ### PodPreset

 This plug-in injects a pod with the fields specified in a matching PodPreset.
@@ -387,6 +416,7 @@ This plug-in will deny any pod that attempts to set certain escalating [Security
 This plug-in implements automation for [serviceAccounts](/docs/user-guide/service-accounts).
 We strongly recommend using this plug-in if you intend to make use of Kubernetes `ServiceAccount` objects.

+
 ## Is there a recommended set of plug-ins to use?

 Yes.