ceph-csi/examples

How to test RBD and CephFS plugins with Kubernetes 1.13

Both rbd and cephfs directories contain plugin-deploy.sh and plugin-teardown.sh helper scripts. You can use those to help you deploy/teardown RBACs, sidecar containers and the plugin in one go. By default, they look for the YAML manifests in ../../deploy/{rbd,cephfs}/kubernetes. You can override this path by running $ ./plugin-deploy.sh /path/to/my/manifests.

Once the plugin is successfully deployed, you'll need to customize storageclass.yaml and secret.yaml manifests to reflect your Ceph cluster setup. Please consult the documentation for info about available parameters.

After configuring the secrets, monitors, etc. you can deploy a testing Pod mounting a RBD image / CephFS volume:

kubectl create -f secret.yaml
kubectl create -f storageclass.yaml
kubectl create -f pvc.yaml
kubectl create -f pod.yaml

Other helper scripts:

• logs.sh output of the plugin
• exec-bash.sh logs into the plugin's container and runs bash

How to test RBD Snapshot feature

Before continuing, make sure you enabled the required feature gate VolumeSnapshotDataSource=true in your Kubernetes cluster.

In the examples/rbd directory you will find two files related to snapshots: snapshotclass.yaml and snapshot.yaml.

Once you created your RBD volume, you'll need to customize at least snapshotclass.yaml and make sure the monitors and pool parameters match your Ceph cluster setup. If you followed the documentation to create the rbdplugin, you shouldn't have to edit any other file.

After configuring everything you needed, deploy the snapshot class:

kubectl create -f snapshotclass.yaml

Verify that the snapshot class was created:

$ kubectl get volumesnapshotclass
NAME                      AGE
csi-rbdplugin-snapclass   4s

Create a snapshot from the existing PVC:

kubectl create -f snapshot.yaml

To verify if your volume snapshot has successfully been created, run the following:

$ kubectl get volumesnapshot
NAME               AGE
rbd-pvc-snapshot   6s

To check the status of the snapshot, run the following:

$ kubectl describe volumesnapshot rbd-pvc-snapshot

Name:         rbd-pvc-snapshot
Namespace:    default
Labels:       <none>
Annotations:  <none>
API Version:  snapshot.storage.k8s.io/v1alpha1
Kind:         VolumeSnapshot
Metadata:
  Creation Timestamp:  2019-02-06T08:52:34Z
  Finalizers:
    snapshot.storage.kubernetes.io/volumesnapshot-protection
  Generation:        5
  Resource Version:  84239
  Self Link:         /apis/snapshot.storage.k8s.io/v1alpha1/namespaces/default/volumesnapshots/rbd-pvc-snapshot
  UID:               8b9b5740-29ec-11e9-8e0f-b8ca3aad030b
Spec:
  Snapshot Class Name:    csi-rbdplugin-snapclass
  Snapshot Content Name:  snapcontent-8b9b5740-29ec-11e9-8e0f-b8ca3aad030b
  Source:
    API Group:  <nil>
    Kind:       PersistentVolumeClaim
    Name:       rbd-pvc
Status:
  Creation Time:  2019-02-06T08:52:34Z
  Ready To Use:   true
  Restore Size:   1Gi
Events:           <none>

To be sure everything is OK you can run rbd snap ls [your-pvc-name] inside one of your Ceph pod.

To restore the snapshot to a new PVC, deploy pvc-restore.yaml and a testing pod pod-restore.yaml:

kubectl create -f pvc-restore.yaml
kubectl create -f pod-restore.yaml

How to enable multi node attach support for RBD

WARNING This feature is strictly for workloads that know how to deal with concurrent acces to the Volume (eg Active/Passive applications). Using RWX modes on non clustered file systems with applications trying to simultaneously access the Volume will likely result in data corruption!

Example process to test the multiNodeWritable feature

Modify your current storage class, or create a new storage class specifically for multi node writers by adding the multiNodeWritable: "enabled" entry to your parameters. Here's an example:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
   name: csi-rbd
provisioner: rbd.csi.ceph.com
parameters:
    monitors: rook-ceph-mon-b.rook-ceph.svc.cluster.local:6789
    pool: rbd
    imageFormat: "2"
    imageFeatures: layering
    csiProvisionerSecretName: csi-rbd-secret
    csiProvisionerSecretNamespace: default
    csiNodePublishSecretName: csi-rbd-secret
    csiNodePublishSecretNamespace: default
    adminid: admin
    userid: admin
    fsType: xfs
    multiNodeWritable: "enabled"
reclaimPolicy: Delete

Now, you can request Claims from the configured storage class that include the ReadWriteMany access mode:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-1
spec:
  accessModes:
  - ReadWriteMany
  resources:
    requests:
      storage: 1Gi
  storageClassName: csi-rbd

Create a POD that uses this PVC:

apiVersion: v1
kind: Pod
metadata:
  name: test-1
spec:
  containers:
   - name: web-server
     image: nginx
     volumeMounts:
       - name: mypvc
         mountPath: /var/lib/www/html
  volumes:
   - name: mypvc
     persistentVolumeClaim:
       claimName: pvc-1
       readOnly: false

Wait for the POD to enter Running state, write some data to /var/lib/www/html

Now, we can create a second POD (ensure the POD is scheduled on a different node; multiwriter single node works without this feature) that also uses this PVC at the same time

apiVersion: v1
kind: Pod
metadata:
  name: test-2
spec:
  containers:
   - name: web-server
     image: nginx
     volumeMounts:
       - name: mypvc
         mountPath: /var/lib/www/html
  volumes:
   - name: mypvc
     persistentVolumeClaim:
       claimName: pvc-1
       readOnly: false

If you access the pod you can check that your data is avaialable at /var/lib/www/html

Testing Raw Block feature in kubernetes with RBD volumes

CSI block volume support is feature-gated and turned off by default. To run CSI with block volume support enabled, a cluster administrator must enable the feature for each Kubernetes component using the following feature gate flags:

--feature-gates=BlockVolume=true,CSIBlockVolume=true

these feature-gates must be enabled on both api-server and kubelet

create a raw-block PVC

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: raw-block-pvc
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Block
  resources:
    requests:
      storage: 1Gi
  storageClassName: csi-rbd

create raw block pvc

kubectl create -f raw-block-pvc.yaml

create a pod to mount raw-block PVC

---
apiVersion: v1
kind: Pod
metadata:
  name: pod-with-raw-block-volume
spec:
  containers:
    - name: fc-container
      image: fedora:26
      command: ["/bin/sh", "-c"]
      args: [ "tail -f /dev/null" ]
      volumeDevices:
        - name: data
          devicePath: /dev/xvda
  volumes:
    - name: data
      persistentVolumeClaim:
        claimName: raw-block-pvc

Create a POD that uses raw block PVC

kubectl create -f raw-block-pod.yaml