HostPath Storage for T4K

This section describes installation of Hostpath CSI driver

HostPath is storage type where volumes refer to directories on the Node (VM/machine) where your Pod is scheduled for running.

In this section we are going to see how to enable HostPath for your Kubernetes Cluster and test the VolumeSnapshot functionality which is the prerequisite for Trilio for Kubernetes (T4K).

Follow the steps below to install and validate the HostPath CSI driver :

1. Clone the hostpath GitHub repository:

   git clone https://github.com/kubernetes-csi/csi-driver-host-path.git

2. Go to specific directory where the installation script is available. This depends on your Kubernetes cluster version

   cd csi-driver-host-path/deploy/kubernetes-1.XX

3. Skip this step if k8s version is less than 1.17

   # Change to the latest supported snapshotter version
   $ SNAPSHOTTER_VERSION=v2.0.1
   
   # Apply VolumeSnapshot CRDs
   $ kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/${SNAPSHOTTER_VERSION}/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml
   $ kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/${SNAPSHOTTER_VERSION}/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml
   $ kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/${SNAPSHOTTER_VERSION}/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml
   
   # Create snapshot controller
   $ kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/${SNAPSHOTTER_VERSION}/deploy/kubernetes/snapshot-controller/rbac-snapshot-controller.yaml
   $ kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/${SNAPSHOTTER_VERSION}/deploy/kubernetes/snapshot-controller/setup-snapshot-controller.yaml

4. Run the shell script based on your cluster OCP/K8s Version. Make sure you install this driver in Default namespace

   ./deploy.sh

5. Wait for the installation to complete and verify if driver is installed correctly.

   Make sure following pods are running
   
   NAME                                                  READY   STATUS      RESTARTS   AGE
   csi-hostpath-attacher-0                               1/1     Running     0          28d
   csi-hostpath-provisioner-0                            1/1     Running     1          28d
   csi-hostpath-resizer-0                                1/1     Running     0          28d
   csi-hostpath-snapshotter-0                            1/1     Running     0          28d
   csi-hostpath-socat-0                                  1/1     Running     0          28d
   csi-hostpathplugin-0                                  3/3     Running     0          28d

6. Create a Storage and VolumeSnapshot Class for Hostpath

   • StorageClass:

     apiVersion: storage.k8s.io/v1
     kind: StorageClass
     metadata:
       name: csi-hostpath-sc
       annotations:
         storageclass.kubernetes.io/is-default-class: "true"
     provisioner: hostpath.csi.k8s.io
     reclaimPolicy: Retain
     volumeBindingMode: Immediate

   • VolumeSnapshotClass:

7. This step we need to use the API version based on K8s/OCP Version.

   1. OCP 4.3/k8s 1.16 : apiVersion: snapshot.storage.k8s.io/v1alpha1

   2. OCP 4.4/K8s 1.17+ : apiVersion: snapshot.storage.k8s.io/v1beta1

8. apiVersion: snapshot.storage.k8s.io/v1alpha1
   kind: VolumeSnapshotClass
   metadata:
     annotations:
       snapshot.storage.kubernetes.io/is-default-class: "true"
     name: default-snapshot-class
   snapshotter: hostpath.csi.k8s.io

   apiVersion: snapshot.storage.k8s.io/v1beta1
   kind: VolumeSnapshotClass
   metadata:
     name: default-snapshot-class
   driver: hostpath.csi.k8s.io
   deletionPolicy: Delete

9. Create a test volume eg: task-pv-claim

   1. apiVersion: v1
      kind: PersistentVolumeClaim
      metadata:
        name: task-pv-claim
      spec:
        storageClassName: csi-hostpath-sc
        accessModes:
          - ReadWriteOnce
        resources:
          requests:
            storage: 50Mi

10. Create a snapshot of task-pv-claim

    1. If using the Alpha version of the API

       apiVersion: snapshot.storage.k8s.io/v1alpha1
       kind: VolumeSnapshot
       metadata:
        name: new-snapshot-demo
        namespace: default
       spec:
        snapshotClassName: default-snapshot-class
        source:
         name: task-pv-claim
         kind: PersistentVolumeClaim

    2. If using Beta version of the API

       apiVersion: snapshot.storage.k8s.io/v1beta1
       kind: VolumeSnapshot
       metadata:
         name: new-snapshot
       spec:
         volumeSnapshotClassName: default-snapshot-class
         source:
           persistentVolumeClaimName: task-pv-claim
       

11. Verify if snapshot and volume snapshot content shows created snapshot.

oc get volumesnapshot
oc get volumesnapshotcontent

kubectl get volumesnapshot
kubectl get volumesnapshotcontent