3 min read | by Jordi Prats
Longhorn is a highly available persistent storage for Kubernetes. It implements distributed block storage using containers and microservices creating a dedicated storage controller for each block device volume and synchronously replicating the volume across multiple replicas stored on multiple nodes. It might sound intimidating, but it's very straightforward to install
On each node we will need to install some dependencies:
So, on Ubuntu we just need to run:
apt-get install open-iscsi jq -y Once ready, we can run the environment_check.sh script as follows to make sure everything is in place:
# curl https://raw.githubusercontent.com/longhorn/longhorn/v1.1.2/scripts/environment_check.sh | bash % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 2794 100 2794 0 0 39914 0 --:--:-- --:--:-- --:--:-- 39914 daemonset.apps/longhorn-environment-check created waiting for pods to become ready (0/1) waiting for pods to become ready (0/1) all pods ready (1/1) MountPropagation is enabled! cleaning up... daemonset.apps "longhorn-environment-check" deleted clean up complete If that looks good we can proceed creating the values.yaml. It's safe to go with the defaults, so we just need to enable the ingress if we want to enable it's web interface:
ingress: enabled: true host: longhorn.local We can install the helm chart as follows:
helm repo add longhorn https://charts.longhorn.io helm repo update helm install longhorn longhorn/longhorn --namespace longhorn-system --create-namespace -f values.yaml We'll have to wait for a while to let Kubernetes create all the required pods:
$ kubectl get pods -n longhorn-system NAME READY STATUS RESTARTS AGE csi-attacher-75588bff58-6njjt 1/1 Running 0 16m csi-attacher-75588bff58-v5fqv 1/1 Running 0 16m csi-attacher-75588bff58-xb5pp 1/1 Running 0 16m csi-provisioner-669c8cc698-dt9wd 1/1 Running 0 16m csi-provisioner-669c8cc698-gmtvm 1/1 Running 0 16m csi-provisioner-669c8cc698-rlx4b 1/1 Running 0 16m csi-resizer-5c88bfd4cf-98sbp 1/1 Running 0 16m csi-resizer-5c88bfd4cf-jltt5 1/1 Running 0 16m csi-resizer-5c88bfd4cf-mgwhj 1/1 Running 0 16m csi-snapshotter-69f8bc8dcf-6kbrn 1/1 Running 0 16m csi-snapshotter-69f8bc8dcf-rr2xj 1/1 Running 0 16m csi-snapshotter-69f8bc8dcf-zhx2w 1/1 Running 0 16m engine-image-ei-d4c780c6-77mcf 1/1 Running 0 17m engine-image-ei-d4c780c6-phgbg 1/1 Running 0 17m engine-image-ei-d4c780c6-z7bzd 1/1 Running 0 17m instance-manager-e-1b82056b 1/1 Running 0 17m instance-manager-e-45737e61 1/1 Running 0 16m instance-manager-e-9a755162 1/1 Running 0 17m instance-manager-r-6b4a827c 1/1 Running 0 8m45s instance-manager-r-758bd997 1/1 Running 0 6m48s longhorn-csi-plugin-nwvjn 2/2 Running 0 16m longhorn-csi-plugin-wbs5h 2/2 Running 0 16m longhorn-csi-plugin-wmqxm 2/2 Running 0 16m longhorn-driver-deployer-75f68555c9-kqp5q 1/1 Running 0 17m longhorn-manager-d4455 1/1 Running 0 17m longhorn-manager-dk7tl 1/1 Running 0 17m longhorn-manager-knxsk 1/1 Running 0 17m longhorn-ui-75ccbd4695-nftq7 1/1 Running 0 17m Once ready we can check that there's a longhorn StorageClass available:
$ kubectl get sc NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE local-path (default) rancher.io/local-path Delete WaitForFirstConsumer false 9d longhorn driver.longhorn.io Delete Immediate true 3d To start using it we can either set it as the default or explicitly set the StorageClass on the PVC:
kind: PersistentVolumeClaim apiVersion: v1 metadata: name: data0-minio-pet2cattle-ss spec: accessModes: - ReadWriteOnce resources: requests: storage: 20Gi storageClassName: longhorn We can see the PVC is using the longhorn StorageClass (6th column):
$ kubectl get pvc -n minio NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE data0-minio-pet2cattle-ss-0-0 Bound pvc-6137ddaf-6f07-491e-b217-a33328d2d4a3 20Gi RWO longhorn 6m7s data1-minio-pet2cattle-ss-0-0 Bound pvc-c1638ade-5b0e-4023-b981-333f95d6888f 20Gi RWO longhorn 6m7s data2-minio-pet2cattle-ss-0-0 Bound pvc-0e288e7d-2e22-454f-96c0-c7122df87c44 20Gi RWO longhorn 6m7s data3-minio-pet2cattle-ss-0-0 Bound pvc-adad20f8-1fb4-4d9d-8c5a-d36e2a5a5c97 20Gi RWO longhorn 6m7s Posted on 13/12/2021