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Kubernetes Hetzner Cloud csi-driver

Getting Started

  1. Create a read+write API token in the Hetzner Cloud Console.

  2. Create a secret containing the token:

    # secret.yml
    apiVersion: v1
    kind: Secret
    metadata:
      name: hcloud
      namespace: kube-system
    stringData:
      token: YOURTOKEN
    

    and apply it:

    kubectl apply -f <secret.yml>
    
  3. Deploy the CSI driver and wait until everything is up and running:

    Have a look at our Version Matrix to pick the correct deployment file.

    kubectl apply -f https://raw.githubusercontent.com/hetznercloud/csi-driver/v2.3.2/deploy/kubernetes/hcloud-csi.yml
    
  4. To verify everything is working, create a persistent volume claim and a pod which uses that volume:

    apiVersion: v1
    kind: PersistentVolumeClaim
    metadata:
      name: csi-pvc
    spec:
      accessModes:
      - ReadWriteOnce
      resources:
        requests:
          storage: 10Gi
      storageClassName: hcloud-volumes
    ---
    kind: Pod
    apiVersion: v1
    metadata:
      name: my-csi-app
    spec:
      containers:
        - name: my-frontend
          image: busybox
          volumeMounts:
          - mountPath: "/data"
            name: my-csi-volume
          command: [ "sleep", "1000000" ]
      volumes:
        - name: my-csi-volume
          persistentVolumeClaim:
            claimName: csi-pvc
    

    Once the pod is ready, exec a shell and check that your volume is mounted at /data.

    kubectl exec -it my-csi-app -- /bin/sh
    

Volumes Encrypted with LUKS

To add encryption with LUKS you have to create a dedicate secret containing an encryption passphrase and duplicate the default hcloud-volumes storage class with added parameters referencing this secret:

apiVersion: v1
kind: Secret
metadata:
 name: encryption-secret
 namespace: kube-system
stringData:
 encryption-passphrase: foobar

--- 

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
 name: hcloud-volumes-encrypted
provisioner: csi.hetzner.cloud
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true
parameters:
 csi.storage.k8s.io/node-publish-secret-name: encryption-secret
 csi.storage.k8s.io/node-publish-secret-namespace: kube-system

Your nodes might need to have cryptsetup installed to mount the volumes with LUKS.

Upgrading

To upgrade the csi-driver version, you just need to apply the new manifests to your cluster.

In case of a new major version, there might be manual steps that you need to follow to upgrade the csi-driver. See the following section for a list of major updates and their required steps.

From v1 to v2

There are three breaking changes between v1.6 and v2.0 that require user intervention. Please take care to follow these steps, as otherwise the update might fail.

Before the rollout:

  1. The secret containing the API token was renamed from hcloud-csi to hcloud. This change was made so both the cloud-controller-manager and the csi-driver can use the same secret. Check that you have a secret hcloud in the namespace kube-system, and that the secret contains the API token, as described in the section Getting Started:

    $ kubectl get secret -n kube-system hcloud
  2. We added a new field to our CSIDriver resource to support CSI volume fsGroup policy management. This change requires a replacement of the CSIDriver object. You need to manually delete the old object:

    $ kubectl delete csidriver csi.hetzner.cloud

    The new CSIDriver will be installed when you apply the new manifests.

  3. Stop the old pods to make sure that only everything is replaced in order and no incompatible pods are running side-by-side:

    $ kubectl delete statefulset -n kube-system hcloud-csi-controller
    $ kubectl delete daemonset -n kube-system hcloud-csi-node
  4. We changed the way the device path of mounted volumes is communicated to the node service. This requires changes to the VolumeAttachment objects, where we need to add information to the status.attachmentMetadata field. Execute the linked script to automatically add the required information. This requires kubectl version v1.24+, even if your cluster is running v1.23.

    $ kubectl version
    $ curl -O https://raw.githubusercontent.com/hetznercloud/csi-driver/main/docs/v2-fix-volumeattachments/fix-volumeattachments.sh
    $ chmod +x ./fix-volumeattachments.sh
    $ ./fix-volumeattachments.sh

Rollout the new manifest:

$ kubectl apply -f https://raw.githubusercontent.com/hetznercloud/csi-driver/v2.3.2/deploy/kubernetes/hcloud-csi.yml

After the rollout:

  1. Delete the now unused secret hcloud-csi in the namespace kube-system:

    $ kubectl delete secret -n kube-system hcloud-csi
  2. Remove old resources that have been replaced:

    $ kubectl delete clusterrolebinding hcloud-csi
    $ kubectl delete clusterrole hcloud-csi
    $ kubectl delete serviceaccount -n kube-system hcloud-csi

Integration with Root Servers

Root servers can be part of the cluster, but the CSI plugin doesn't work there. Taint the root server as follows to skip that node for the daemonset.

kubectl label nodes <node name> instance.hetzner.cloud/is-root-server=true

Versioning policy

We aim to support the latest three versions of Kubernetes. After a new Kubernetes version has been released we will stop supporting the oldest previously supported version. This does not necessarily mean that the CSI driver does not still work with this version. However, it means that we do not test that version anymore. Additionally, we will not fix bugs related only to an unsupported version.

Kubernetes CSI Driver Deployment File
1.27 2.3.2 https://raw.githubusercontent.com/hetznercloud/csi-driver/v2.3.2/deploy/kubernetes/hcloud-csi.yml
1.26 2.3.2 https://raw.githubusercontent.com/hetznercloud/csi-driver/v2.3.2/deploy/kubernetes/hcloud-csi.yml
1.25 2.3.2 https://raw.githubusercontent.com/hetznercloud/csi-driver/v2.3.2/deploy/kubernetes/hcloud-csi.yml
1.24 2.3.2 https://raw.githubusercontent.com/hetznercloud/csi-driver/v2.3.2/deploy/kubernetes/hcloud-csi.yml
1.23 2.2.0 https://raw.githubusercontent.com/hetznercloud/csi-driver/v2.2.0/deploy/kubernetes/hcloud-csi.yml
1.22 1.6.0 https://raw.githubusercontent.com/hetznercloud/csi-driver/v1.6.0/deploy/kubernetes/hcloud-csi.yml
1.21 1.6.0 https://raw.githubusercontent.com/hetznercloud/csi-driver/v1.6.0/deploy/kubernetes/hcloud-csi.yml
1.20 1.6.0 https://raw.githubusercontent.com/hetznercloud/csi-driver/v1.6.0/deploy/kubernetes/hcloud-csi.yml