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To add the resources VolumeSnapshotContent and VolumeSnapshotClass to your MicroK8s cluster, you'll need to ensure that the VolumeSnapshot feature is supported and enabled in your Kubernetes environment. These resources are part of the Kubernetes CSI Snapshot feature, which became stable in Kubernetes 1.20. Here's a step-by-step guide to enable and configure these resources in MicroK8s:

Step 1: Ensure Kubernetes Version is Compatible

VolumeSnapshotContent and VolumeSnapshotClass are part of the Kubernetes CSI Snapshot feature, which requires a compatible version of Kubernetes (1.20 or newer).

First, check your MicroK8s Kubernetes version:

microk8s kubectl version

If your Kubernetes version is lower than 1.20, consider upgrading MicroK8s to a newer version:

sudo snap refresh microk8s --channel=latest/stable

Step 2: Enable CSI Snapshot Feature in MicroK8s

The VolumeSnapshotContent and VolumeSnapshotClass resources require a CSI driver with snapshot capabilities. MicroK8s does not ship a CSI snapshot controller by default, but you can install the external snapshot controller and CRDs manually. Follow these steps to add the necessary CRDs and controllers.

2.1. Install Snapshot Controller CRDs

Kubernetes requires the VolumeSnapshot CRDs to be installed before you can use snapshot resources. You can manually install these CRDs by applying the following:

kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.0.1/client/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.0.1/client/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.0.1/client/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml

These CRDs define the following custom resources:

2.2. Install the Snapshot Controller

The CSI Snapshot feature also requires an external snapshot controller to manage volume snapshots. You can install the external snapshot controller using the following manifest:

kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.0.1/deploy/kubernetes/snapshot-controller/rbac-snapshot-controller.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.0.1/deploy/kubernetes/snapshot-controller/setup-snapshot-controller.yaml

This will deploy the CSI Snapshot Controller in the kube-system namespace.

Step 3: Create VolumeSnapshotClass

Once the necessary CRDs and controllers are in place, you can create a VolumeSnapshotClass to define the snapshot behavior for a specific CSI driver. Here's an example VolumeSnapshotClass for a CSI driver that supports snapshots:

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: csi-snapshot-class
driver: csi-driver-name # Replace with your CSI driver name
deletionPolicy: Delete

In the driver field, replace csi-driver-name with the name of the CSI driver you're using (such as csi-hostpath or any other CSI driver that supports snapshots).

Apply the VolumeSnapshotClass resource:

kubectl apply -f volumesnapshotclass.yaml

Step 4: Create VolumeSnapshotContent

The VolumeSnapshotContent resource represents the actual snapshot created from a persistent volume (PV). You can either create a pre-provisioned or dynamic snapshot.

Example of Pre-Provisioned VolumeSnapshotContent

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotContent
metadata:
  name: snapshot-content-1
spec:
  deletionPolicy: Delete
  driver: csi-driver-name # Replace with your CSI driver name
  source:
    snapshotHandle: snapshot-id # Replace with the ID of the pre-provisioned snapshot
  volumeSnapshotRef:
    name: snapshot-1
    namespace: default

In this example:

Apply this resource:

kubectl apply -f volumesnapshotcontent.yaml

Step 5: Create VolumeSnapshot (For Dynamic Snapshots)

If you want to dynamically create snapshots from existing Persistent Volume Claims (PVCs), you can create a VolumeSnapshot resource. This assumes your CSI driver supports dynamic snapshot creation.

Here’s an example:

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: my-snapshot
  namespace: default
spec:
  volumeSnapshotClassName: csi-snapshot-class # Replace with your VolumeSnapshotClass name
  source:
    persistentVolumeClaimName: my-pvc # Replace with the PVC you want to snapshot

Apply the VolumeSnapshot resource:

kubectl apply -f volumesnapshot.yaml

After this, a snapshot will be created for the specified PVC, and Kubernetes will automatically manage the VolumeSnapshotContent resource in the background.

Step 6: Verify Snapshot Resources

After creating the snapshot resources, you can verify that everything is working by checking the status of the resources:

kubectl get volumesnapshotclass
kubectl get volumesnapshot
kubectl get volumesnapshotcontent

You should see the VolumeSnapshotClass, VolumeSnapshot, and VolumeSnapshotContent resources if everything is set up correctly.

Summary of Key Steps

  1. Ensure you're using Kubernetes 1.20+ in MicroK8s.
  2. Install the CSI Snapshot CRDs.
  3. Deploy the external Snapshot Controller.
  4. Create a VolumeSnapshotClass for your CSI driver.
  5. Create VolumeSnapshotContent for pre-provisioned snapshots or VolumeSnapshot for dynamic snapshots.
  6. Verify that the snapshots are working correctly using kubectl get commands.

By following these steps, you will add the VolumeSnapshotContent and VolumeSnapshotClass resources to your MicroK8s cluster and enable snapshot capabilities for your storage.