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ocm-kubevirt-samples

This repo contains sample kubevirt resources for deployment in Kubernetes or OpenShift clusters.

Using in OpenShift

Use ACM console to deploy the VM, enable DR or delete the VM.

Deploying the VM

  1. Create new application using:

    • repo: this repo URL
    • branch: main
    • path: one of the vm-*-odr-* directories

  2. To enable DR assign DR Policy

Testing DR

Use ACM console to perform failover or relocate actions.

Deleting the VM

Use ACM console to delete the application.

Using in Kubernetes

In Kubernetes you need to deploy the VM and DR resources using the command line tools or API. In this example we use the ramen testing environment.

Setting up the testing environment

Ramen test environment creates 3 minikube clusters (hub, dr1, dr2) on your laptop, including OCM, Rook, Kubevirt, CDI, and many other components required by Ramen.

See the User quick start guide for complete instructions.

Important

When starting the environment, use the regional-dr-kubvirt.yaml configuration.

Adding your SSH key

If you want to inject your SSH key into the VM, you need to replace the included SSH public key with your own public key.

  1. Fork this repo in github
  2. Replace the contents of the vm-standalone-pvc-k8s/test_rsa.pub with your public key (e.g. ~/.ssh/id_rsa.pub)
  3. Update channel/channel.yaml to point to your repository (e.g. https://github.com/my-github-user/ocm-kubevirt-samples.git)
  4. If you are not using the main branch update subscription/subscription.yaml to point to the right branch.

Deploying the VM subscription

To start the VM deploy the subscription:

kubectl apply -k subscription --context hub

The subscription starts the VM vm-standalone-pvc-k8s on one of the clusters in the default clusterset.

The subscription is optimized for Ramen minikube based test environment. To use in another setup you may need to modify the resources.

Inspecting the VM status

To find where the VM was placed look at the PlacementDecisions status:

kubectl get placementdecisions -n kubevirt-sample --context hub \
    -o jsonpath='{.items[0].status.decisions[0].clusterName}{"\n"}'

To inspect the VM and DR resources use:

watch -n 5 kubectl get vm,vmi,pod,pvc,vrg,vr -n kubevirt-sample --context dr1

Example output:

Every 5.0s: kubectl get vm,vmi,pod,pvc,vrg,vr -n kubevirt-sample --context dr1

NAME                                   AGE     STATUS    READY
virtualmachine.kubevirt.io/sample-vm   5m51s   Running   True

NAME                                           AGE     PHASE     IP            NODENAME   READY
virtualmachineinstance.kubevirt.io/sample-vm   5m51s   Running   10.244.0.61   dr1        True

NAME                                READY   STATUS    RESTARTS   AGE
pod/virt-launcher-sample-vm-chsrh   1/1     Running   0          5m51s

NAME                                  STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS      AGE
persistentvolumeclaim/sample-vm-pvc   Bound    pvc-149bd414-c1b8-443c-90f7-7e30fc519eb4   128Mi      RWX            rook-ceph-block   5m51s

At this point there there are no vrg and vr resources, since we did not enable DR for the VM yet.

We can inspect the underlying RBD image backing the VM PVC using the rook-ceph kubectl krew plugin:

kubectl rook-ceph --context dr1 rbd du -p replicapool

Example output:

NAME                                          PROVISIONED  USED
csi-vol-a3fdb384-2e31-49f1-bd48-a97b2d79f981      128 MiB  80 MiB

Enabling DR for the VM

To allow Ramen to protect the VM, you need to disable OCM scheduling by adding an annotation to the VM placement:

kubectl annotate placement kubevirt-placement \
    cluster.open-cluster-management.io/experimental-scheduling-disable=true \
    --namespace kubevirt-sample \
    --context hub

Deploy the DR resources to enable DR:

kubectl apply -k dr --context hub

At this point Ramen controls the VM placement and protects the VM data by replicating it to the secondary cluster ("dr2").

To wait until the VM data is replicating to the secondary cluster, wait for the PeerReady condition:

kubectl wait drpc kubevirt-drpc \
    --for condition=PeerReady \
    --namespace kubevirt-sample \
    --timeout 5m \
    --context hub

Inspecting the VM DR status

We can inspect the VM DR status using the DRPlacementControl resource on the hub cluster:

watch -n 5 kubectl get drpc -n kubevirt-sample --context hub -o wide

Example output:

Every 5.0s: kubectl get drpc -n kubevirt-sample --context hub -o wide

NAME            AGE   PREFERREDCLUSTER   FAILOVERCLUSTER   DESIREDSTATE   CURRENTSTATE   PROGRESSION   START TIME             DURATION       PEER READY
kubevirt-drpc   51s   dr1                                                 Deployed	 Completed     2023-11-19T20:26:53Z   5.035609263s   True

To get more details we can watch the VM and DR reosurces on the managed cluster:

watch -n 5 kubectl get vm,vmi,pod,pvc,vrg,vr -n kubevirt-sample --context dr1

Example output:

Every 5.0s: kubectl get vm,vmi,pod,pvc,vrg,vr -n kubevirt-sample --context dr1

NAME                                   AGE   STATUS    READY
virtualmachine.kubevirt.io/sample-vm   16m   Running   True

NAME                                           AGE   PHASE     IP            NODENAME   READY
virtualmachineinstance.kubevirt.io/sample-vm   16m   Running   10.244.0.61   dr1        True

NAME                                READY   STATUS    RESTARTS   AGE
pod/virt-launcher-sample-vm-chsrh   1/1     Running   0          16m

NAME                                  STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS      AGE
persistentvolumeclaim/sample-vm-pvc   Bound    pvc-149bd414-c1b8-443c-90f7-7e30fc519eb4   128Mi      RWX            rook-ceph-block   16m

NAME                                                        DESIREDSTATE   CURRENTSTATE
volumereplicationgroup.ramendr.openshift.io/kubevirt-drpc   primary        Primary

NAME                                                               AGE     VOLUMEREPLICATIONCLASS   PVCNAME         DESIREDSTATE   CURRENTSTATE
volumereplication.replication.storage.openshift.io/sample-vm-pvc   2m46s   vrc-sample               sample-vm-pvc   primary        Primary

The cirros VM used by this example includes a logger service logging a message every 10 seconds:

virtctl ssh cirros@sample-vm -n kubevirt-sample --known-hosts= --context dr1 -c 'head /var/log/ramen.log'

Example output:

Sun Nov 19 20:13:20 UTC 2023 START uptime=3.33
Sun Nov 19 20:13:30 UTC 2023 UPDATE
Sun Nov 19 20:13:40 UTC 2023 UPDATE
Sun Nov 19 20:13:50 UTC 2023 UPDATE
Sun Nov 19 20:14:00 UTC 2023 UPDATE
Sun Nov 19 20:14:10 UTC 2023 UPDATE
Sun Nov 19 20:14:20 UTC 2023 UPDATE
Sun Nov 19 20:14:30 UTC 2023 UPDATE
Sun Nov 19 20:14:40 UTC 2023 UPDATE
Sun Nov 19 20:14:50 UTC 2023 UPDATE

Ramen set up RBD mirroring for the underlying RBD image. The same image is created on the secondary cluster ("dr2"):

kubectl rook-ceph --context dr2 rbd du -p replicapool

Example output:

NAME                                          PROVISIONED  USED
csi-vol-a3fdb384-2e31-49f1-bd48-a97b2d79f981      128 MiB  80 MiB

In case of a disaster in the primary cluster, we can start the VM using the replica on the secondary cluster.

Failing over to another cluster

In case of disaster you can force the VM to run on the other cluster. The VM will start on the other cluster using the data from the last replication. Data since the last replication is lost.

To simulate a disaster we can pause the minkube VM running cluster dr1:

virsh -c qemu:///system suspend dr1

To start Failover action, patch the VM DRPlacementControl resource to set action and failoverCluster:

kubectl patch drpc kubevirt-drpc \
    --patch '{"spec": {"action": "Failover", "failoverCluster": "dr2"}}' \
    --type merge \
    --namespace kubevirt-sample \
    --context hub

The VM will start on the failover cluster ("dr2"). Nothing will change on the primary cluster ("dr1") since it is still paused.

Inspecting the /var/log/ramen.log via SSH show how much data was lost during the failover:

virtctl ssh cirros@sample-vm -n kubevirt-sample --known-hosts= --context dr2 -c 'tail -f /var/log/ramen.log'

Example output:

Sun Nov 19 20:33:42 UTC 2023 UPDATE
Sun Nov 19 20:33:53 UTC 2023 UPDATE
Sun Nov 19 20:34:03 UTC 2023 UPDATE
Sun Nov 19 20:34:13 UTC 2023 UPDATE
Sun Nov 19 20:34:23 UTC 2023 UPDATE
Sun Nov 19 20:34:33 UTC 2023 UPDATE
Sun Nov 19 20:34:43 UTC 2023 UPDATE
Sun Nov 19 20:34:53 UTC 2023 UPDATE
Sun Nov 19 20:37:43 UTC 2023 START uptime=3.18
Sun Nov 19 20:37:53 UTC 2023 UPDATE
Sun Nov 19 20:38:03 UTC 2023 UPDATE

To enable replication from the secondary cluster to the primary cluster, we need to recover the primary cluster. In this example we can resume the minikube VM:

virsh -c qemu:///system resume dr1

Ramen will clean up the VM resources from the primary cluster and enable RBD mirroring from the secondary cluster ("dr2") to the primary cluster ("dr1").

To wait until the VM data is replicated again to the other cluster:

kubectl wait drpc kubevirt-drpc \
    --for condition=PeerReady \
    --namespace kubevirt-sample \
    --timeout 5m \
    --context hub

Since the primary cluster is recovered, we can move the VM back to the primary cluster.

Relocating to another cluster

To move the VM back to the original cluster after a disaster you can use the Relocate action. The VM will be terminated on the current cluster, and started on the other cluster. No data is lost during this operation.

Patch the VM DRPlacementControl resource to set action and if needed, preferredCluster.

kubectl patch drpc kubevirt-drpc \
    --patch '{"spec": {"action": "Relocate", "preferredCluster": "dr1"}}' \
    --type merge \
    --namespace kubevirt-sample \
    --context hub

The VM will terminate on the current cluster and will start on the preferred cluster.

To wait until the VM is relocated to the primary cluster, wait until the drpc phase is Relocated:

kubectl wait drpc kubevirt-drpc \
    --for jsonpath='{.status.phase}=Relocated' \
    --namespace kubevirt-sample \
    --timeout 5m \
    --context hub

Inspecting /var/log/ramen.log shows that the VM was terminated cleanly on the secondary cluster ("dr2") and started on the primary cluster ("dr1"). No data was lost!

virtctl ssh cirros@sample-vm -n kubevirt-sample --known-hosts= --context dr1 -c 'tail -f /var/log/ramen.log'

Example output:

Sun Nov 19 20:41:53 UTC 2023 UPDATE
Sun Nov 19 20:42:03 UTC 2023 UPDATE
Sun Nov 19 20:42:13 UTC 2023 UPDATE
Sun Nov 19 20:42:23 UTC 2023 UPDATE
Sun Nov 19 20:42:33 UTC 2023 UPDATE
Sun Nov 19 20:42:43 UTC 2023 UPDATE
Sun Nov 19 20:42:53 UTC 2023 UPDATE
Sun Nov 19 20:42:58 UTC 2023 STOP
Sun Nov 19 20:41:17 UTC 2023 START uptime=3.45
Sun Nov 19 20:41:27 UTC 2023 UPDATE
Sun Nov 19 20:41:37 UTC 2023 UPDATE

To wait until the VM is replicating data again to the secondary cluster, wait for the PeerReady condition:

kubectl wait drpc kubevirt-drpc \
    --for condition=PeerReady \
    --namespace kubevirt-sample \
    --timeout 5m \
    --context hub

Disable DR for the VM

Delete the dr resources to disable DR:

kubectl delete -k dr --context hub

Enable OCM scheduling again by deleting the placement annotation we added before:

kubectl annotate placement kubevirt-placement \
    cluster.open-cluster-management.io/experimental-scheduling-disable- \
    --namespace kubevirt-sample \
    --context hub

At this point OCM controls the VM and the storage used for replicating the VM data on the DR clusters will be reclaimed.

Undeploying the VM

Delete the subscription to stop and delete the VM:

kubectl delete -k subscription --context hub

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