Use credentials when calling ControllerModifyVolume

[nixpanic]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind api-change

/kind bug

/kind cleanup
/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:

Storage providers expect to obtain secrets from the
ControllerMoodifyVolume CSI procedure. Without these credentials, it may
not be possible to apply the parameters of a VolumeAttributeClass.

A CSIPersistentVolumeSource does not have ControllerModifySecretRef
(like ControllerExpandSecretRef), so in order to resolve credentials a
secret reference from annotations on the PersistentVolume are used:

• volume.kubernetes.io/controller-modify-secret-name
• volume.kubernetes.io/controller-modify-secret-namespace

In absence of these annotations, the ControllerExpandSecretRef of the
CSIPersistentVolumeSource used as a fallback.

Which issue(s) this PR fixes:

Related to kubernetes-csi/external-provisioner#1440

Special notes for your reviewer:

Posting this for early review. @gadididi is implementing ControllerModifyVolume in Ceph-CSI and found out about the missing secrets the hard way.

Approach has been discussed in a thread at #csi.

/cc carlory gnufied

Does this PR introduce a user-facing change?:

A StorageClass can use `csi.storage.k8s.io/controller-modify-secret-name` and `csi.storage.k8s.io/controller-modify-secret-namespace` to reference the credentials that should be used to modify a volume according to the parameters of a VolumeAttributeClass. In absence of these credentials, the credentials of `controller-expand-secret`are used as a fallback.

[k8s-ci-robot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[nixpanic]

Container image for testing at quay.io/nixpanic/csi-resizer:pr544.

[carlory]

/cc @sunnylovestiramisu
Please have a look when it is ready for review.

[nixpanic]

@gnufied, this has been updated with the changes as discussed/proposed in the Slack #csi channel. kubernetes-csi/external-provisioner#1440 is the related change for the external-provisioner.

[Madhu-1]

LGTM

[k8s-ci-robot]

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