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Using Longhorn Storage

Longhorn is a lightweight, reliable and easy-to-use distributed block storage system for Kubernetes.

Pre-requisites

  1. https://longhorn.io/docs/1.0.2/deploy/install/#installation-requirements
  2. Core dns addon
  3. Helm3 addon
  4. Ingress addon

Steps:

Instructions taken from Longhorn site. Tailored with MicroK8s addons.

  1. Enable dns addon
microk8s enable dns
  1. Enable helm3 addon
microk8s enable helm3
  1. Add longhorn helm repo
microk8s helm3 repo add longhorn https://charts.longhorn.io
  1. Helm update
microk8s helm3 repo update
  1. Install Longhorn
microk8s kubectl create namespace longhorn-system
# for testing use "/tmp/longhorn" as storage location
microk8s helm3 install longhorn longhorn/longhorn --namespace longhorn-system \
  --set defaultSettings.defaultDataPath="/longhorn" \
  --set csi.kubeletRootDir="/var/snap/microk8s/common/var/lib/kubelet"
  1. Check all pods are Running
microk8s kubectl -n longhorn-system get pods -A

NAME                                        READY   STATUS    RESTARTS   AGE   IP           NODE                           NOMINATED NODE   READINESS GATES
instance-manager-e-32b33e77                 1/1     Running   0          46m   10.1.39.5    microk8s-worker-cetacean-0     <none>           <none>
instance-manager-r-0d98aaf2                 1/1     Running   0          46m   10.1.39.6    microk8s-worker-cetacean-0     <none>           <none>
engine-image-ei-ee18f965-d2vjd              1/1     Running   0          46m   10.1.39.4    microk8s-worker-cetacean-0     <none>           <none>
engine-image-ei-ee18f965-58hsg              1/1     Running   0          46m   10.1.7.67    microk8s-controller-cetacean   <none>           <none>
longhorn-manager-9m49w                      1/1     Running   0          47m   10.1.39.3    microk8s-worker-cetacean-0     <none>           <none>
longhorn-manager-mvtcp                      1/1     Running   0          47m   10.1.7.66    microk8s-controller-cetacean   <none>           <none>
longhorn-manager-nxqjn                      1/1     Running   2          47m   10.1.98.65   microk8s-worker-cetacean-1     <none>           <none>
engine-image-ei-ee18f965-9zvlf              1/1     Running   0          46m   10.1.98.66   microk8s-worker-cetacean-1     <none>           <none>
instance-manager-e-8130572b                 1/1     Running   0          30m   10.1.98.70   microk8s-worker-cetacean-1     <none>           <none>
instance-manager-r-0b9655bc                 1/1     Running   0          30m   10.1.98.71   microk8s-worker-cetacean-1     <none>           <none>
instance-manager-r-361e6769                 1/1     Running   0          29m   10.1.7.70    microk8s-controller-cetacean   <none>           <none>
instance-manager-e-bc17fd46                 1/1     Running   0          29m   10.1.7.71    microk8s-controller-cetacean   <none>           <none>
longhorn-driver-deployer-658fdf45cc-8sf8r   1/1     Running   0          27m   10.1.7.72    microk8s-controller-cetacean   <none>           <none>
csi-attacher-79d88c7c98-7p9h2               1/1     Running   0          27m   10.1.39.7    microk8s-worker-cetacean-0     <none>           <none>
csi-attacher-79d88c7c98-8xbnn               1/1     Running   0          27m   10.1.98.73   microk8s-worker-cetacean-1     <none>           <none>
csi-attacher-79d88c7c98-xlw7j               1/1     Running   0          27m   10.1.7.73    microk8s-controller-cetacean   <none>           <none>
longhorn-csi-plugin-cqlqm                   2/2     Running   0          27m   10.1.98.74   microk8s-worker-cetacean-1     <none>           <none>
csi-resizer-d8487b59-rrxkl                  1/1     Running   0          27m   10.1.39.8    microk8s-worker-cetacean-0     <none>           <none>
csi-provisioner-5749f9cd4f-22gck            1/1     Running   0          27m   10.1.7.74    microk8s-controller-cetacean   <none>           <none>
csi-provisioner-5749f9cd4f-hrgnn            1/1     Running   0          27m   10.1.98.75   microk8s-worker-cetacean-1     <none>           <none>
longhorn-csi-plugin-6phhz                   2/2     Running   0          27m   10.1.39.9    microk8s-worker-cetacean-0     <none>           <none>
csi-resizer-d8487b59-z24rk                  1/1     Running   0          27m   10.1.7.75    microk8s-controller-cetacean   <none>           <none>
csi-resizer-d8487b59-8wwxd                  1/1     Running   0          27m   10.1.98.76   microk8s-worker-cetacean-1     <none>           <none>
csi-provisioner-5749f9cd4f-ccmwx            1/1     Running   0          27m   10.1.39.10   microk8s-worker-cetacean-0     <none>           <none>
longhorn-csi-plugin-cd4mx                   2/2     Running   0          27m   10.1.7.76    microk8s-controller-cetacean   <none>           <none>
longhorn-ui-7788d4f485-9649z                1/1     Running   0          26m   10.1.39.11   microk8s-worker-cetacean-0     <none>           <none>
  1. Enable Ingress addon
microk8s enable ingress
  1. Install Ingress Resource
cat <<EOF | microk8s kubectl apply -f -
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: longhorn
  namespace: longhorn-system
spec:
  rules:
  - host: longhorn-ui.geeks.sg
    http:
      paths:
        - path: /
          pathType: Prefix
          backend:
            service:
              name: longhorn-frontend
              port:
                number: 80
EOF
  1. Access the Longhorn UI.

Please note that this do not have Authentication in place.

Go to your browser and access http://longhorn-ui.geeks.sg or whatever you have in your ingress.

Screenshot

  1. Install sample pod using the longhorn PV
cat <<EOF | microk8s kubectl apply -f -
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: longhorn-volv-pvc
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: longhorn
  resources:
    requests:
      storage: 10Gi
---
apiVersion: v1
kind: Pod
metadata:
  name: security-context-demo
spec:
  securityContext:
    runAsUser: 1000
    runAsGroup: 3000
    fsGroup: 2000
  containers:
  - name: sec-ctx-demo
    image: busybox
    command: [ "sh", "-c", "sleep 10h" ]
    livenessProbe:
      exec:
        command:
          - ls
          - /data/lost+found
      initialDelaySeconds: 5
      periodSeconds: 5
    volumeMounts:
    - name: volv
      mountPath: /data
    ports:
    - containerPort: 80
  volumes:
  - name: volv
    persistentVolumeClaim:
      claimName: longhorn-volv-pvc         
EOF
  1. Create files inside the pod
$ microk8s kubectl get pods -o wide
NAME                    READY   STATUS    RESTARTS   AGE     IP           NODE                         NOMINATED NODE   READINESS GATES
security-context-demo   1/1     Running   0          2m56s   10.1.39.13   microk8s-worker-cetacean-0   <none>           <none>

$ microk8s kubectl exec -it security-context-demo -- sh
/ # cd /data
/data # pwd
/data
/data # ls -l
total 16
drwx------    2 root     root         16384 Dec 11 08:20 lost+found
/data # echo "Hello" > my-file.txt
/data # cat /data/my-file.txt 
Hello
/data #

Backup to Digitalocean Spaces

Digitalocean Spaces is an S3 compatible object store.

  1. Create Secret which contains the DigitalOcean Spaces
cat <<EOF | kubectl apply -f -
# same secret for longhorn-system namespace
apiVersion: v1
kind: Secret
metadata:
  name: spaces-secret
  namespace: longhorn-system
type: Opaque
data:
  AWS_ACCESS_KEY_ID: `echo -n $DO_SPACES_ACCESS_KEY | base64 -w 0` # longhorn-test-access-key
  AWS_SECRET_ACCESS_KEY: `echo -n $DO_SPACES_SECRET_KEY | base64 -w 0`
  AWS_ENDPOINTS: `echo -n "https://nyc3.digitaloceanspaces.com/" | base64 -w 0`
  VIRTUAL_HOSTED_STYLE: dHJ1ZQ== # true
EOF
  1. Setup in General>Settings

Backup Settings

  1. Create Backup

Backup Volume