Expand Volume

  1. Create GKE cluster with 3 nodes and install Longhorn.

  2. Create deployment and write some data to it.

  3. In Longhorn, set replica-replenishment-wait-interval to 0.

  4. Add a new node-pool. Later Longhorn components will be automatically deployed on the nodes in this pool.

    GKE_NODEPOOL_NAME_NEW=<new-nodepool-name>
GKE_REGION=<gke-region>
GKE_CLUSTER_NAME=<gke-cluster-name>
GKE_IMAGE_TYPE=Ubuntu
GKE_MACHINE_TYPE=<gcp-machine-type>
GKE_DISK_SIZE_NEW=<new-disk-size-in-gb>
GKE_NODE_NUM=<number-of-nodes>
gcloud container node-pools create ${GKE_NODEPOOL_NAME_NEW} \
  --region ${GKE_REGION} \
  --cluster ${GKE_CLUSTER_NAME} \
  --image-type ${GKE_IMAGE_TYPE} \
  --machine-type ${GKE_MACHINE_TYPE} \
  --disk-size ${GKE_DISK_SIZE_NEW} \
  --num-nodes ${GKE_NODE_NUM}

gcloud container node-pools list \
  --zone ${GKE_REGION} \
  --cluster ${GKE_CLUSTER_NAME}

  5. Using Longhorn UI to disable the disk scheduling and request eviction for nodes in the old node-pool.

  6. Cordon and drain Kubernetes nodes in the old node-pool.

    GKE_NODEPOOL_NAME_OLD=<old-nodepool-name>
for n in `kubectl get nodes | grep ${GKE_CLUSTER_NAME}-${GKE_NODEPOOL_NAME_OLD}- | awk '{print $1}'`; do
  kubectl cordon $n && \
  kubectl drain $n --ignore-daemonsets --pod-selector='app!=csi-attacher,app!=csi-provisioner' --delete-emptydir-data
done

  7. Delete old node-pool.

    gcloud container node-pools delete ${GKE_NODEPOOL_NAME_OLD}\
  --zone ${GKE_REGION} \
  --cluster ${GKE_CLUSTER_NAME}

  8. Check the deployment in step 2 still running and data exist, and check volume expanded as expected through Longhorn UI.

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