OpenEBS Local Device CSI Driver

CSI Driver for using Local Block Devices

Project Status

Currently, the Device-LocalPV CSI Driver is in pre-alpha.

Usage

Prerequisites

Before installing the device CSI driver please make sure your Kubernetes Cluster must meet the following prerequisites:

Disks are available on the node with a single 10MB partition having partition name used to identify the disk
You have access to install RBAC components into kube-system namespace. The OpenEBS Device driver components are installed in kube-system namespace to allow them to be flagged as system critical components.

Supported System

K8S : 1.18+

OS : Ubuntu

Setup

Find the disk which you want to use for the Device LocalPV, for testing a loopback device can be used

truncate -s 1024G /tmp/disk.img
sudo losetup -f /tmp/disk.img --show

Create the meta partition on the loop device which will be used for provisioning volumes

sudo parted /dev/loop9 mklabel gpt
sudo parted /dev/loop9 mkpart test-device 1MiB 10MiB

Installation

Deploy the Operator yaml

kubectl apply -f https://raw.githubusercontent.com/openebs/device-localpv/master/deploy/device-operator.yaml

Deployment

1. Create a Storage class

$ cat sc.yaml

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: openebs-device-sc
allowVolumeExpansion: true
parameters:
  devname: "test-device"
provisioner: device.csi.openebs.io
volumeBindingMode: WaitForFirstConsumer

Check the doc on storageclasses to know all the supported parameters for Device LocalPV

Device Availability

If the device with meta partition is available on certain nodes only, then make use of topology to tell the list of nodes where we have the devices available. As shown in the below storage class, we can use allowedTopologies to describe device availability on nodes.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: openebs-device-sc
allowVolumeExpansion: true
parameters:
  devname: "test-device"
provisioner: device.csi.openebs.io
allowedTopologies:
- matchLabelExpressions:
  - key: kubernetes.io/hostname
    values:
      - device-node1
      - device-node2

The above storage class tells that device with meta partition "test-device" is available on nodes device-node1 and device-node2 only. The Device CSI driver will create volumes on those nodes only.

2. Create the PVC

$ cat pvc.yaml

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: csi-devicepv
spec:
  storageClassName: openebs-device-sc
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 4Gi

Create a PVC using the storage class created for the Device driver.

3. Deploy the application

Create the deployment yaml using the pvc backed by Device driver storage.

$ cat fio.yaml

apiVersion: v1
kind: Pod
metadata:
  name: fio
spec:
  restartPolicy: Never
  containers:
  - name: perfrunner
    image: openebs/tests-fio
    command: ["/bin/bash"]
    args: ["-c", "while true ;do sleep 50; done"]
    volumeMounts:
       - mountPath: /datadir
         name: fio-vol
    tty: true
  volumes:
  - name: fio-vol
    persistentVolumeClaim:
      claimName: csi-devicepv

After the deployment of the application, we can go to the node and see that the partition is created and is being used as a volume by the application for reading/writting the data.

4. Deprovisioning

for deprovisioning the volume we can delete the application which is using the volume and then we can go ahead and delete the pv, as part of deletion of pv the partition will be wiped and deleted from the device.

$ kubectl delete -f fio.yaml
pod "fio" deleted
$ kubectl delete -f pvc.yaml
persistentvolumeclaim "csi-devicepv" deleted

iyashu / device-localpv