Setting up Longhorn for Kubernetes storage

16 Nov 2024 in Blog

When it came time to install the flight check-in app that I had created into my Kubernetes cluster, I realized I have no way for my workloads to utilize storage. Then I came across Longhorn during a web search for storage solutions. I suppose there are other options like Ceph. Initially forgetting about the Ceph option, I decided to go with Longhorn and I’m glad I did because some of the things I read about Ceph made it sound like a bad choice for a small bare metal Kubernetes cluster. But honestly, there are pros and cons to both Longhorn and Ceph.

Longhorn setup

Longhorn (one of the pros) was extremely easy to setup (I read that’s not the case with Ceph), all I did was follow this page. I ran the Environment Check Script, which is actually deprecated and will be removed soon (in v1.8.0). It was replaced by the Longhorn Command Line Tool (I ran that tool as well). These are the steps I followed.

1. Run Environment Check Script

   curl -sSfL https://raw.githubusercontent.com/longhorn/longhorn/v1.7.2/scripts/environment_check.sh | bash
   

   The output stated that I needed to install the package, nfs-common and load a module, iscsi_tcp.

2. Run Longhorn Command Line Tool

   curl -sSfL -o longhornctl https://github.com/longhorn/cli/releases/download/v1.7.2/longhornctl-linux-amd64
   chmod +x longhornctl
   ./longhornctl check preflight
   

   The output of the Longhorn Command Line Tool stated that I additionally needed to load the module, dm_crypt.

3. On worker nodes 1 and 2, as previously stated, I had to install the package nfs-common and load a couple of modules.

   sudo apt install nfs-common
   sudo modprobe iscsi_tcp
   sudo modprobe dm_crypt
   

   Then put the modules in /etc/modules-load.d/ so they load automatically if and when the system reboots.

   sudo tee /etc/modules-load.d/longhorn-storage.conf<<EOF
   iscsi_tcp
   dm_crypt
   EOF
   

   You must re-read values from all system directories.

   sudo sysctl --system
   

4. Install Longhorn via Helm

   helm repo add longhorn https://charts.longhorn.io
   helm repo update
   helm install longhorn longhorn/longhorn --namespace longhorn-system --create-namespace --version 1.7.2
   

5. Last step is to create the StorageClass.

   kind: StorageClass
   apiVersion: storage.k8s.io/v1
   metadata:
     name: longhorn
   provisioner: driver.longhorn.io
   allowVolumeExpansion: true
   reclaimPolicy: Delete
   volumeBindingMode: Immediate
   parameters:
     numberOfReplicas: "3"
     staleReplicaTimeout: "2880"
     fromBackup: ""
     fsType: "ext4"
   

That’s it! I’m now able to use my Longhorn storage!

Links

• DevOps GitHub repo