gardener-extension-csi-driver-lvm

Project Gardener implements the automated management and operation of Kubernetes clusters as a service. This controller implements Gardener's extension contract for providing csi-driver-lvm in a shoot cluster.

It reconciles the Extension resources of type: csi-driver-lvm.

For more detailed documentation about the extension contract, please refer to the Gardener docs.

As a safety measurement, the extension checks for the old csi-lvm and stops reconciling if the old driver is still available.

The following storage classes will be created by default:

• csi-driver-lvm-linear for linear volumes
• csi-driver-lvm-mirror for mirrored volumes for improved redundancy on multiple physical volumes
• csi-driver-lvm-striped for striped volumes for improved performance on multiple physical volumes
• csi-lvm for backwards compatibility with type linear.

When encryption is enabled (see below), three additional LUKS-encrypted storage classes are created:

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

See docs/migration.md for further information about migrating from csi-lvm to csi-driver-lvm.

Example

An example ControllerRegistration resource that can be used to register this controller to Gardener can be found here.

LUKS Encryption

LUKS block-device encryption can be enabled per shoot by adding an encryption field to the providerConfig. When set, the three encrypted storage classes above are created. Each class instructs the CSI node plugin to open the LUKS device using a key read from a Secret in the shoot cluster.

Setup

1. Create the LUKS key Secret in the shoot cluster:

   kubectl -n <namespace> create secret generic csi-lvm-encryption-secret \
     --from-literal=passphrase="$(openssl rand -base64 32)"

   Important: This Secret is part of your cluster's recovery data. Back it up securely. Losing it makes encrypted volumes permanently inaccessible.

2. Reference the Secret in the shoot's providerConfig:

   extensions:
   - type: csi-driver-lvm
     providerConfig:
       apiVersion: csi-driver-lvm.metal.extensions.gardener.cloud/v1alpha1
       kind: CsiDriverLvmConfig
       devicePattern: /dev/nvme[0-9]n[0-9]
       hostWritePath: /etc/lvm
       encryption:
         secretRef:
           name: csi-lvm-encryption-secret
           namespace: <namespace>

3. Create a PVC using one of the encrypted storage classes:

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: my-encrypted-pvc
   spec:
     accessModes: [ReadWriteOnce]
     storageClassName: csi-driver-lvm-linear-encrypted
     resources:
       requests:
         storage: 10Gi

Notes

• Both secretRef.name and secretRef.namespace are required when encryption is set; the extension will refuse to reconcile with either field empty.
• The Secret is user-owned and is not managed by the extension. It will not be deleted or overwritten during reconciliation.
• StorageClass.parameters are immutable in Kubernetes. If you need to change the secret reference, delete the encrypted storage classes manually and allow the extension to recreate them.
• Removing encryption from providerConfig deletes the encrypted storage classes but does not affect existing PVCs or the underlying LUKS devices.

Development

This extension can be developed in the gardener-local devel environment. Before make sure you have created loop-devices on your machine (identical to how you would develop the csi-driver-lvm locally, refer to the repository docs for further information).

for i in 100 101; do fallocate -l 1G loop${i}.img ; sudo losetup /dev/loop${i} loop${i}.img; done
sudo losetup -a
# use this for recreation or cleanup
# for i in 100 101; do sudo losetup -d /dev/loop${i}; rm -f loop${i}.img; done

1. Start up the local devel environment
2. The extension's docker image can be pushed into Kind using make push-to-gardener-local
3. Install the extension kubectl apply -k example/
4. Parametrize the example/shoot.yaml and apply with kubectl -f example/shoot.yaml

Feedback and Support

Feedback and contributions are always welcome! Please report bugs or suggestions as GitHub issues or reach out to our community.