[cinder-csi-plugin] Validate volume capabilities in RPC call CreateVolume

[nschad]

What this PR does / why we need it:

Cinder currently only supports VolumeCapability_AccessMode_SINGLE_NODE_WRITER, therefore we should not allow it to provision volumes with AccessMode RWX. This will only lead to "errors" when replica > 1.

Additionally, the spec states (as I understand it) that the CreateVolume RPC call must support all specified volume capabilities, which was not the case previously. So this is why I added the check here.

Example of Error Message in K8s

 Warning  ProvisioningFailed    2s (x2 over 3s)  cinder.csi.openstack.org_csi-driver-controller-foo  failed to provision volume with StorageClass "bar": rpc error: code = InvalidArgument desc = volume access mode MULTI_NODE_MULTI_WRITER not supported

Which issue this PR fixes(if applicable):
fixes #

Special notes for reviewers:

Release note:

[cinder-csi-plugin] Enforce VolumeCapabilities when creating volumes.

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[kayrus]

@nschad thanks for the PR. can you share a detailed step-by-step instructions on how to reproduce a problem?

[nschad]

@nschad thanks for the PR. can you share a detailed step-by-step instructions on how to reproduce a problem?

Sure

1. Create a Deployment with an Volume in RWX mode.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: simple-deployment
spec:
  replicas: 2
  selector:
    matchLabels:
      app: simple-app
  template:
    metadata:
      labels:
        app: simple-app
    spec:
      containers:
      - name: simple-container
        image: nginx
        volumeMounts:
        - mountPath: /mnt/data
          name: simple-volume
      volumes:
      - name: simple-volume
        persistentVolumeClaim:
          claimName: simple-pvc

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: simple-pvc
spec:
  accessModes:
    - ReadWriteMany  # RWX access mode
  resources:
    requests:
      storage: 5Gi

2. Watch the Volume be successfully bounded to Pod 1/Node A and embrace the error you will definitely get when your Pod 2 on Node B can't attach the volume, because cinder doesn't do MULTI_NODE_MULTI_POD

In my opinion the volume shouldn't be provisioned in the first place with AccessMode RWX. That is exactly what this PR does.

[kayrus]

In my opinion the volume shouldn't be provisioned in the first place with AccessMode RWX. That is exactly what this PR does.

I see, but I wonder whether this can be considered as a default behavior for someone else. Do you know what's the behavior of other CSI drivers, e.g. GCE or AWS?

UPD: basically I expect that csi-provisioner handles this and doesn't allow to create a ReadWriteMany volume based on the CSI plugin capabilities.

[nschad]

In my opinion the volume shouldn't be provisioned in the first place with AccessMode RWX. That is exactly what this PR does.

I see, but I wonder whether this can be considered as a default behavior for someone else. Do you know what's the behavior of other CSI drivers, e.g. GCE or AWS?

Yes, for example:

• https://github.com/digitalocean/csi-digitalocean/blob/master/driver/controller.go#L96-L98
• AWS-EBS doing it in ControllerPublishVolume https://github.com/kubernetes-sigs/aws-ebs-csi-driver/blob/a25f651b6f2e39ba1ef79dbac4d638f36ad62292/pkg/driver/controller.go#L398-L400

UPD: basically I expect that csi-provisioner handles this and doesn't allow to create a ReadWriteMany volume based on the CSI plugin capabilities.

Yeah maybe but it's just not the reality currently. There is the RPC call ValidateVolumeCapabilities (also implemented here) but that only gets called AFAIK for pre-provisioned volumes which is for us like 0.01% of the use case.