Merge pull request #43777 from sunnylovestiramisu/blog

Add a blog post about VolumeAttributesClass

Author: k8s-ci-robot

content/en/blog/_posts/2023-12-15-volume-attributes-class/index.md

@@ -0,0 +1,177 @@
+---
+layout: blog
+title: "Kubernetes 1.29: VolumeAttributesClass for Volume Modification"
+date: 2023-12-15
+slug: kubernetes-1-29-volume-attributes-class
+---
+
+**Author**: Sunny Song (Google)
+
+The v1.29 release of Kubernetes introduced an alpha feature to support modifying a volume
+by changing the `volumeAttributesClassName` that was specified for a PersistentVolumeClaim (PVC).
+With the feature enabled, Kubernetes can handle updates of volume attributes other than capacity.
+Allowing volume attributes to be changed without managing it through different
+provider's APIs directly simplifies the current flow.
+
+You can read about VolumeAttributesClass usage details in the Kubernetes documentation 
+or you can read on to learn about why the Kubernetes project is supporting this feature.
+
+
+## VolumeAttributesClass
+
+The new `storage.k8s.io/v1alpha1` API group provides two new types:
+
+**VolumeAttributesClass**
+
+Represents a specification of mutable volume attributes defined by the CSI driver.
+The class can be specified during dynamic provisioning of PersistentVolumeClaims,
+and changed in the PersistentVolumeClaim spec after provisioning.
+
+**ModifyVolumeStatus**
+
+Represents the status object of `ControllerModifyVolume` operation.
+
+With this alpha feature enabled, the spec of PersistentVolumeClaim defines VolumeAttributesClassName
+that is used in the PVC. At volume provisioning, the `CreateVolume` operation will apply the parameters in the
+VolumeAttributesClass along with the parameters in the StorageClass.
+
+When there is a change of volumeAttributesClassName in the PVC spec,
+the external-resizer sidecar will get an informer event. Based on the current state of the configuration,
+the resizer will trigger a CSI ControllerModifyVolume.
+More details can be found in [KEP-3751](https://github.com/kubernetes/enhancements/blob/master/keps/sig-storage/3751-volume-attributes-class/README.md).
+
+## How to use it
+
+If you want to test the feature whilst it's alpha, you need to enable the relevant feature gate
+in the `kube-controller-manager` and the `kube-apiserver`. Use the `--feature-gates` command line argument:
+
+
+```
+--feature-gates="...,VolumeAttributesClass=true"
+```
+
+
+It also requires that the CSI driver has implemented the ModifyVolume API.
+
+
+### User flow
+
+If you would like to see the feature in action and verify it works fine in your cluster, here's what you can try:
+
+
+1. Define a StorageClass and VolumeAttributesClass
+
+   ```yaml
+   apiVersion: storage.k8s.io/v1
+   kind: StorageClass
+   metadata:
+     name: csi-sc-example
+   provisioner: pd.csi.storage.gke.io
+   parameters:
+     disk-type: "hyperdisk-balanced"
+   volumeBindingMode: WaitForFirstConsumer
+   ```
+
+
+   ```yaml
+   apiVersion: storage.k8s.io/v1alpha1
+   kind: VolumeAttributesClass
+   metadata:
+     name: silver
+   driverName: pd.csi.storage.gke.io
+   parameters:
+     provisioned-iops: "3000"
+     provisioned-throughput: "50"
+   ```
+
+
+2. Define and create the PersistentVolumeClaim
+
+   ```yaml
+   apiVersion: v1
+   kind: PersistentVolumeClaim
+   metadata:
+     name: test-pv-claim
+   spec:
+     storageClassName: csi-sc-example
+     volumeAttributesClassName: silver
+     accessModes:
+       - ReadWriteOnce
+     resources:
+       requests:
+         storage: 64Gi
+   ```
+
+
+3. Verify that the PersistentVolumeClaim is now provisioned correctly with:
+
+   ```
+   kubectl get pvc
+   ```
+
+
+4. Create a new VolumeAttributesClass gold:
+
+   ```yaml
+   apiVersion: storage.k8s.io/v1alpha1
+   kind: VolumeAttributesClass
+   metadata:
+     name: gold
+   driverName: pd.csi.storage.gke.io
+   parameters:
+     iops: "4000"
+     throughput: "60"
+   ```
+
+
+5. Update the PVC with the new VolumeAttributesClass and apply:
+
+   ```yaml
+   apiVersion: v1
+   kind: PersistentVolumeClaim
+   metadata:
+     name: test-pv-claim
+   spec:
+     storageClassName: csi-sc-example
+     volumeAttributesClassName: gold
+     accessModes:
+       - ReadWriteOnce
+     resources:
+       requests:
+         storage: 64Gi
+   ```
+
+
+6. Verify that PersistentVolumeClaims has the updated VolumeAttributesClass parameters with:
+
+   ```
+   kubectl describe pvc <PVC_NAME>
+   ```
+
+## Next steps
+
+* See the [VolumeAttributesClass KEP](https://kep.k8s.io/3751) for more information on the design
+* You can view or comment on the [project board](https://github.com/orgs/kubernetes-csi/projects/72) for VolumeAttributesClass
+* In order to move this feature towards beta, we need feedback from the community,
+  so here's a call to action: add support to the CSI drivers, try out this feature,
+  consider how it can help with problems that your users are having…
+
+
+## Getting involved
+
+We always welcome new contributors. So, if you would like to get involved, you can join our [Kubernetes Storage Special Interest Group](https://github.com/kubernetes/community/tree/master/sig-storage) (SIG).
+
+If you would like to share feedback, you can do so on our [public Slack channel](https://app.slack.com/client/T09NY5SBT/C09QZFCE5).
+
+Special thanks to all the contributors that provided great reviews, shared valuable insight and helped implement this feature (alphabetical order):
+
+*   Baofa Fan (calory)
+*   Ben Swartzlander (bswartz)
+*   Connor Catlett (ConnorJC3)
+*   Hemant Kumar (gnufied)
+*   Jan Šafránek (jsafrane)
+*   Joe Betz (jpbetz)
+*   Jordan Liggitt (liggitt)
+*   Matthew Cary (mattcary)
+*   Michelle Au (msau42)
+*   Xing Yang (xing-yang)