Managing storage

Managing Block Storage volumes with the Scaleway CSI

Published on 12 August 2021

Security & Identity (IAM):

You may need certain IAM permissions to carry out some actions described on this page. This means:

you are the Owner of the Scaleway Organization in which the actions will be carried out, or
you are an IAM user of the Organization, with a policy granting you the necessary permission sets

Requirements:

You have an account and are logged into the Scaleway console
You have created a Kubernetes cluster running on Scaleway Instances (v1.21+)
You have a Scaleway Project or Organization ID, Access and Secret key

The Scaleway Block Volume Container Storage Interface (CSI) driver is an implementation of the CSI interface to provide a way to manage Scaleway Block Volumes through a container orchestration system, like Kubernetes. It is installed by default on every Kubernetes Kapsule and Kosmos cluster.

Features

Following is a list of functionalities implemented by the Scaleway CSI driver.

Block device resizing

The Scaleway CSI driver implements the resize feature (example for Kubernetes). It allows an online resize (without the need to detach the block device). However resizing can only be done upwards, decreasing a volume’s size is not supported.

Raw Block Volume

Raw Block Volumes allows the block volume to be exposed directly to the container as a block device, instead of a mounted filesystem. To enable it, the volumeMode needs to be set to Block. For instance, here is a PVC in raw block volume mode:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-raw-pvc
spec:
  volumeMode: Block
  [...]

At-Rest encryption

Support for volume encryption. See in examples

Volume snapshots

Volume snapshots allows the user to create a snapshot of a specific block volume.

Volume statistics

The Scaleway CSI driver implements the NodeGetVolumeStats CSI method. It is used to gather statistics about the used block volumes. In Kubernetes, kubelet exposes these metrics.

Kubernetes

This section is Kubernetes specific. Note that Scaleway CSI driver may work for older Kubernetes version than those announced. The CSI driver allows to use Persistent Volumes in Kubernetes.

Creating persistent volumes with Scaleway Block Storage

Create a PersistentVolumeClaim and use it as a volume inside the pod of a deployment.
```
$ kubectl apply -f pvc-deployment/pvc.yaml
```

Create the deployment that will use this volume:

$ kubectl apply -f pvc-deployment/deployment.yaml

Creating raw block volumes

Create a block volume and make it available in the pod as a raw block device. In order to do so, volumeMode must be set to Block:
```
$ kubectl apply -f raw-volume/pvc.yaml
```
Create a pod that will use this raw volume. In order to do so, volumesDevices must be used, instead of the traditional volumeMounts:
```
$ kubectl apply -f raw-volume/pod.yaml
```

Exec into the container and use the volume as a classic block device:

$ kubectl exec -it my-awesome-block-volume-app sh
/ # ls -al /dev/xvda
brw-rw----    1 root     disk        8,  32 Mar 23 12:34 /dev/xvda
/ # dd if=/dev/zero of=/dev/xvda bs=1024k count=100
100+0 records in
100+0 records out
104857600 bytes (100.0MB) copied, 0.043702 seconds, 2.2GB/s

Importing existing Scaleway volumes

If you have an already existing volume, with the ID 11111111-1111-1111-111111111111 in the zone fr-par-1, you can import it by creating the following PV:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: test-pv
spec:
  capacity:
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  storageClassName: scw-bssd
  csi:
    driver: csi.scaleway.com
    volumeHandle: fr-par-1/11111111-1111-1111-111111111111
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: topology.csi.scaleway.com/zone
          operator: In
          values:
          - fr-par-1

Once the PV is created, create a PVC with the same attributes (here scw-bssd as storage class and a size of 5Gi):
```
$ kubectl apply -f importing/pvc.yaml
```

Ceate a pod that uses this volume:

$ kubectl apply -f importing/pod.yaml

Encrypting volumes

This plugin supports at rest encryption of the volumes with Cryptsetup/LUKS.

Note:

Resizing an encrypted volume does not work.

Storage class parameters

In order to have an encrypted volume, encrypted: true needs to be added to the StorageClass parameters. You will also need an passphrase to encrypt/decrypt the volume, which is take from the secrets passed to the NodeStageVolume method.

The external-provisioner can be used to pass down the wanted secret to the CSI plugin (v1.0.1+).

Two additional parameters are needed on the StorageClass:

csi.storage.k8s.io/node-stage-secret-name: The name of the secret
csi.storage.k8s.io/node-stage-secret-namespace: The namespace of the secret

The secret needs to have the passphrase in the entry with the key encryptionPassphrase.

For instance with the following secret:

apiVersion: v1
kind: Secret
metadata:
  name: enc-secret
  namespace: default
type: Opaque
data:
  encryptionPassphrase: bXlhd2Vzb21lcGFzc3BocmFzZQ==

and the following StorageClass:

allowVolumeExpansion: false # not yet supported
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: "scw-bssd-enc"
provisioner: csi.scaleway.com
reclaimPolicy: Delete
volumeBindingMode: Immediate
parameters:
  encrypted: "true"
  csi.storage.k8s.io/node-stage-secret-name: "enc-secret"
  csi.storage.k8s.io/node-stage-secret-namespace: "default"

all the PVC created with the StorageClass scw-bssd-enc will be encrypted at rest with the passphrase myawesomepassphrase.

The Per Volume Secret can also be used to avoid having one passphrase per StorageClass.