Lab Adv 02: Deploy Longhorn on OKS

Lab Objective

By the end of this lab, you will be able to:

• Deploy Longhorn on an OKS cluster
• Create persistent volumes using Longhorn
• Test a ReadWriteMany volume
• Validate data persistence in a multi-AZ environment

Environment Preparation

Before starting this lab, make sure you have the following:

• An OKS cluster.
  👉 Click here to access the OKS cluster creation lab if not already done.
• Helm installed.

Creating a Dedicated Longhorn NodePool

Create a nodepool.yaml file:

apiVersion: oks.dev/v1beta2
kind: NodePool
metadata:
  name: nodepool-01
spec:
  desiredNodes: 1
  nodeType: tinav7.c4r8p2
  zones:
  - eu-west-2a
  - eu-west-2b
  - eu-west-2c
  volumes:
  - device: root
    size: 100
    type: "gp2"
    dir: '/'
  - device: xvdl
    size: 100
    type: "gp2"
    dir: "/var/lib/longhorn"

Apply the configuration:

kubectl apply -f nodepool.yaml

Installing iSCSI on the Nodes

Create the configuration-iscsi.yaml file:

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: longhorn-iscsi-installation
  labels:
    app: longhorn-iscsi-installation
  annotations:
    command: &cmd OS=$(grep -E "^ID_LIKE=" /etc/os-release | cut -d '=' -f 2); if [[ -z "${OS}" ]]; then OS=$(grep -E "^ID=" /etc/os-release | cut -d '=' -f 2); fi; if [[ "${OS}" == *"debian"* ]]; then sudo apt-get update -q -y && sudo apt-get install -q -y open-iscsi nfs-common cryptsetup && sudo systemctl -q enable iscsid && sudo systemctl start iscsid && sudo modprobe iscsi_tcp; elif [[ "${OS}" == *"suse"* ]]; then sudo zypper --gpg-auto-import-keys -q refresh && sudo zypper --gpg-auto-import-keys -q install -y open-iscsi && sudo systemctl -q enable iscsid && sudo systemctl start iscsid && sudo modprobe iscsi_tcp; else sudo yum makecache -q -y && sudo yum --setopt=tsflags=noscripts install -q -y iscsi-initiator-utils && echo "InitiatorName=$(/sbin/iscsi-iname)" > /etc/iscsi/initiatorname.iscsi && sudo systemctl -q enable iscsid && sudo systemctl start iscsid && sudo modprobe iscsi_tcp; fi && if [ $? -eq 0 ]; then echo "iscsi install successfully"; else echo "iscsi install failed error code $?"; fi
spec:
  selector:
    matchLabels:
      app: longhorn-iscsi-installation
  template:
    metadata:
      labels:
        app: longhorn-iscsi-installation
    spec:
      nodeSelector:
        node-pool: nodepool-01
      hostNetwork: true
      hostPID: true
      initContainers:
      - name: iscsi-installation
        command:
          - nsenter
          - --mount=/proc/1/ns/mnt
          - --
          - bash
          - -c
          - *cmd
        image: alpine:3.17
        securityContext:
          privileged: true
      containers:
      - name: sleep
        image: registry.k8s.io/pause:3.1
  updateStrategy:
    type: RollingUpdate

Apply the DaemonSet:

kubectl apply -f configuration-iscsi.yaml

Installing Longhorn

Create the namespace:

kubectl create ns longhorn-system

Add the Helm repository:

helm repo add longhorn https://charts.longhorn.io
helm repo update

Install Longhorn:

helm install longhorn longhorn/longhorn --namespace longhorn-system

Check the pods:

kubectl get pods -n longhorn-system

Creating the Longhorn StorageClass

Create the longhorn-storageclass.yaml file:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: longhorn-3repl
provisioner: driver.longhorn.io
allowVolumeExpansion: true
reclaimPolicy: Delete
volumeBindingMode: Immediate
parameters:
  numberOfReplicas: "3"
  staleReplicaTimeout: "2880"
  replicaAutoBalance: "least-effort"
  fsType: "ext4"
  nfsOptions: "vers=4.2,noresvport,softerr,timeo=600,retrans=5"

Apply the StorageClass:

kubectl apply -f longhorn-storageclass.yaml

Creating the PersistentVolumeClaim

Create the pvc.yaml file:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: rwx-test-claim
  namespace: longhorn-system
spec:
  accessModes:
    - ReadWriteMany
  storageClassName: longhorn-3repl
  resources:
    requests:
      storage: 3Gi

kubectl apply -f pvc.yaml

Verifying Longhorn Volumes

kubectl get volumes.longhorn.io -n longhorn-system
## Expected result:

NAME                                       DATA ENGINE   STATE      ROBUSTNESS   SCHEDULED   SIZE
pvc-d1359fcd-9267-4b28-903a-1912a1d1af10   v1            detached   unknown                  3221225472

kubectl get replicas.longhorn.io -n longhorn-system

## Expected result:

NAME                                                  DATA ENGINE   STATE     NODE               DISK
pvc-d1359fcd-9267-4b28-903a-1912a1d1af10-r-0baeabda   v1            stopped   ip-10-50-110-132   202e26f6-0f49-4733-8b13-5787febd0b16
pvc-d1359fcd-9267-4b28-903a-1912a1d1af10-r-0efa26c4   v1            stopped   ip-10-50-65-223    b325f185-de59-4a5a-98f3-daa3e83eea72
pvc-d1359fcd-9267-4b28-903a-1912a1d1af10-r-aa17101c   v1            stopped   ip-10-50-32-166    b7dc5742-2297-46b7-8904-d5a5440c5d8b

Accessing the Longhorn UI

kubectl port-forward -n longhorn-system svc/longhorn-frontend 8080:80

Access: 👉 http://localhost:8080

Expected result:

• Volume rwx-test-claim is Healthy
• 3 replicas on different nodes
• Replicas appear in stopped state until a pod mounts the volume

Deploying an Application Using the RWX Volume

Create the deployment-nginx.yaml file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-rwx-demo
  namespace: longhorn-system
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx-rwx-demo
  template:
    metadata:
      labels:
        app: nginx-rwx-demo
    spec:
      nodeSelector:
        node-pool: nodepool-01
      containers:
        - name: nginx
          image: nginx:alpine
          volumeMounts:
            - name: shared-data
              mountPath: /usr/share/nginx/html
          command: ["/bin/sh", "-c"]
          args:
            - |
              echo "Welcome!" > /usr/share/nginx/html/index.html;
              while true; do
                echo "$(date) — $(hostname)" >> /usr/share/nginx/html/dates.log;
                sleep 60;
              done
      volumes:
        - name: shared-data
          persistentVolumeClaim:
            claimName: rwx-test-claim

kubectl apply -f deployment-nginx.yaml

Replicas should now be in RUNNING state:

kubectl get replicas.longhorn.io

# Expected result:

NAME                                                  DATA ENGINE   STATE     NODE               DISK
pvc-f6d331a7-002f-4a26-b4bc-0042ae816836-r-13f4eaf0   v1            running   ip-10-50-110-132   202e26f6-0f49-4733-8b13-5787febd0b16
pvc-f6d331a7-002f-4a26-b4bc-0042ae816836-r-bbe908b3   v1            running   ip-10-50-32-166    b7dc5742-2297-46b7-8904-d5a5440c5d8b
pvc-f6d331a7-002f-4a26-b4bc-0042ae816836-r-c3fa3af1   v1            running   ip-10-50-65-223    b325f185-de59-4a5a-98f3-daa3e83eea72

Verifying Volume Sharing

kubectl exec -it <pod-name> -- tail -f /usr/share/nginx/html/dates.log

## Expected result:
# Pod 1 :
kubectl exec -it nginx-rwx-demo-6b777c9db8-n29n5 -- tail -f /usr/share/nginx/html/dates.log
Mon Jan 26 12:53:23 UTC 2026 — nginx-rwx-demo-6b777c9db8-xvrd2
Mon Jan 26 12:53:24 UTC 2026 — nginx-rwx-demo-6b777c9db8-w298m
Mon Jan 26 12:53:25 UTC 2026 — nginx-rwx-demo-6b777c9db8-n29n5

# Pod 2 :

kubectl exec -it nginx-rwx-demo-6b777c9db8-w298m -- tail -f /usr/share/nginx/html/dates.log
Mon Jan 26 12:53:23 UTC 2026 — nginx-rwx-demo-6b777c9db8-xvrd2
Mon Jan 26 12:53:24 UTC 2026 — nginx-rwx-demo-6b777c9db8-w298m
Mon Jan 26 12:53:25 UTC 2026 — nginx-rwx-demo-6b777c9db8-n29n5
Mon Jan 26 12:54:23 UTC 2026 — nginx-rwx-demo-6b777c9db8-xvrd2

Multi-AZ Resilience Test

kubectl drain <node-name> --ignore-daemonsets --delete-emptydir-data

The pod is automatically recreated on another node. Verification:

kubectl exec -it <new-pod> -- tail /usr/share/nginx/html/dates.log

Expected result:

—> data is still present