csi-driver-lvm

CSI DRIVER LVM utilizes local storage of Kubernetes nodes to provide persistent storage for pods.

It automatically creates hostPath based persistent volumes on the nodes.

Underneath it creates a LVM logical volume on the local disks. A comma-separated list of grok pattern, which disks to use must be specified.

This CSI driver is derived from csi-driver-host-path and csi-lvm

Currently it can create, delete, mount, unmount and resize block and filesystem volumes via lvm

For the special case of block volumes, the filesystem-expansion has to be performed by the app using the block device

Installation

Helm charts for installation are located in a separate repository called helm-charts. If you would like to contribute to the helm chart, please raise an issue or pull request there.

You have to set the devicePattern for your hardware to specify which disks should be used to create the volume group.

helm install --repo https://helm.metal-stack.io mytest helm/csi-driver-lvm --set lvm.devicePattern='/dev/nvme[0-9]n[0-9]'

Now you can use one of following storageClasses:

  • csi-driver-lvm-linear
  • csi-driver-lvm-mirror
  • csi-driver-lvm-striped

To get the previous old and now deprecated csi-lvm-sc-linear, ... storageclasses, set helm-chart value compat03x=true.

Migration

If you want to migrate your existing PVC to / from csi-driver-lvm, you can use korb.

Todo

  • implement CreateSnapshot(), ListSnapshots(), DeleteSnapshot()

Development

TL;DR:

./start-minikube-on-linux.sh
helm install --repo https://helm.metal-stack.io mytest helm/csi-driver-lvm --set lvm.devicePattern='/dev/loop[0-1]'

Start minikube and create dummy volumes

minikube start --memory 4g
minikube ssh 'for i in 0 1; do fallocate -l 1G loop${i} ; sudo losetup -f loop${i}; sudo losetup -a ; done'

On minikube we have to copy a "real" losetup:

In minikube losetup is a symlink to busybox.

The busybox implentation of losetup lacks some flags on which the kubernetes currently depends on. (see https://github.com/kubernetes/kubernetes/issues/83265 )

 minikube ssh 'sudo rm /sbin/losetup'
 scp -o 'StrictHostKeyChecking=no' -i $(minikube ssh-key) /usr/sbin/losetup  docker@$(minikube ip):/tmp/losetup
 minikube ssh 'sudo mv /tmp/losetup /sbin/losetup'

Build

make
docker build
docker push

Replace metalstack/lvmplugin:latest image in helm/csi-driver-lvm/values.yaml

Deploy

helm install --repo https://helm.metal-stack.io mytest helm/csi-driver-lvm

Test

kubectl apply -f examples/csi-pvc-raw.yaml
kubectl apply -f examples/csi-pod-raw.yaml


kubectl apply -f examples/csi-pvc.yaml
kubectl apply -f examples/csi-app.yaml

kubectl delete -f examples/csi-pod-raw.yaml
kubectl delete -f examples/csi-pvc-raw.yaml

kubectl delete -f  examples/csi-app.yaml
kubectl delete -f examples/csi-pvc.yaml

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