Setup Longhorn

Download the Longhorn Manifest YAMLs

Longhorn's manifest files are available in their GitHub repository. You can apply them directly to the Kubernetes cluster:

kubectl apply -f https://raw.githubusercontent.com/longhorn/longhorn/master/deploy/longhorn.yaml

This command will pull the entire Longhorn deployment YAML, which configures everything Longhorn requires inside the longhorn-system namespace.

Monitor the Deployment Progress

After applying the manifest, you'll see various Kubernetes objects like Pods, Services, DaemonSets, and CRDs being created. You can monitor them with the following command:

kubectl get all -n longhorn-system

Especially watch the status of the Pods.

It will take a couple of minutes for all required components to pull the images from the Docker registry, configure themselves, and become ready.

Verify Custom Resource Definitions (CRDs)

Longhorn uses Custom Resource Definitions (CRDs) for managing and storing information about volumes, nodes, and engines.

Check if the Longhorn CRDs have been installed properly:

kubectl get crds | grep longhorn

You should see a list of Longhorn-related CRDs like:

• instancemanagers.longhorn.io
• volumes.longhorn.io
• nodes.longhorn.io
• replicas.longhorn.io
• and others.

These CRDs are the foundation of Longhorn's integration into your Kubernetes cluster.

Verify Longhorn Components (Pods, DaemonSet)

Ensure that all Longhorn components are running (Pods and DaemonSet) using:

kubectl get pods -n longhorn-system

You should see Longhorn pods running, like:

• longhorn-manager-{pod-name}
• longhorn-instance-manager-{pod-name}
• longhorn-ui-{pod-name}
• longhorn-driver-deployer-{pod-name}

Additionally, verify that the longhorn-manager DaemonSet has pods on every node in your cluster, as it’s responsible for managing Longhorn processes on each node:

kubectl get ds -n longhorn-system

Check that the DaemonSet has Desired pods on all your nodes, and Current matches the desired pod count.

Accessing the Longhorn UI

Longhorn provides a web-based UI for managing your storage. To access it, you will need to expose its service. We cover this in the next section "Expose Longhorn Dashboard using Traefik Ingress".

Configure Nodes for Longhorn Storage

Longhorn automatically recognizes your Kubernetes nodes, but you may want to configure how disks on your nodes are used for storage.

You can do this through the Longhorn UI under the Node & Disk section. Here you can:

• Determine how much space is allocated on each node.
• Specify custom directories for disk storage (e.g., /mnt/disk instead of default paths).
• Set replication factors (i.e., how many copies of a volume will be stored across nodes).

Test Longhorn - Creating a PVC

Let’s verify that Longhorn is working by creating a test Persistent Volume Claim (PVC). Here’s how you can create a StorageClass and a sample PVC.

Create the Longhorn StorageClass

To create a StorageClass for Longhorn, you need to define one so that Longhorn can dynamically provision volumes. You can use the default settings, but feel free to customize, especially the number of replicas depending on how many nodes you have.

Create a file named longhorn-storageclass.yaml:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: longhorn
provisioner: driver.longhorn.io
parameters:
  numberOfReplicas: "2"
  staleReplicaTimeout: "30"
allowVolumeExpansion: true
reclaimPolicy: Retain
volumeBindingMode: Immediate

Then apply this StorageClass:

kubectl apply -f longhorn-storageclass.yaml

Create a PVC Using Longhorn

Now create a sample Persistent Volume Claim (PVC) to test that Longhorn can provision volumes:

Create a longhorn-pvc.yaml file:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: longhorn-pvc
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: longhorn
  resources:
    requests:
      storage: 2Gi

Apply the PVC:

kubectl apply -f longhorn-pvc.yaml

Check the status of the PVC:

kubectl get pvc

Once it’s Bound, you know Longhorn successfully provisioned your storage.

Optionally Deploy a Pod Using the PVC

To further verify the PVC is working, you can deploy a simple pod (for example, the NGINX web server) that mounts the Longhorn volume:

Create a simple nginx-pod.yaml file:

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - image: nginx
    name: nginx
    volumeMounts:
    - name: data
      mountPath: /usr/share/nginx/html
  volumes:
  - name: data
    persistentVolumeClaim:
      claimName: longhorn-pvc

Apply the pod:

kubectl apply -f nginx-pod.yaml

Once the pod is running, Longhorn storage is working as expected.

Monitor Longhorn

Longhorn offers monitoring and management tools (both in the UI and via the CLI) to track the status of volumes, nodes, and replicas.

Key areas to check:

• Volumes: Make sure volumes are healthy and properly replicated.
• Replicas: Ensure replicas are collaborating across your cluster nodes to ensure data redundancy.