Avoid panicking when snapshotting a non-CSI PV

[leonardoce]

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:

This PR avoids the external-snapshotter controller from panicking when the user requests a VolumeGroupSnapshot across non-CSI PVs.

In my tests, master was failing with:

goroutine 124 [running]:
k8s.io/apimachinery/pkg/util/runtime.HandleCrash({0x0, 0x0, 0xc0000f8800?})
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/vendor/k8s.io/apimachinery/pkg/util/runtime/runtime.go:56 +0xcd
panic({0x17ff940?, 0x29eba50?})
	/Users/leonardo.cecchi/.asdf/installs/golang/1.21.9/go/src/runtime/panic.go:914 +0x21f
github.com/kubernetes-csi/external-snapshotter/v7/pkg/common-controller.(*csiSnapshotCommonController).createGroupSnapshotContent(0xc00031ad00, 0xc0008883c0)
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/pkg/common-controller/groupsnapshot_controller_helper.go:757 +0x2db
github.com/kubernetes-csi/external-snapshotter/v7/pkg/common-controller.(*csiSnapshotCommonController).syncUnreadyGroupSnapshot(0xc0000f8ff0?, 0xc0008883c0)
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/pkg/common-controller/groupsnapshot_controller_helper.go:445 +0x105b
github.com/kubernetes-csi/external-snapshotter/v7/pkg/common-controller.(*csiSnapshotCommonController).syncGroupSnapshot(0xc00031ad00, 0xc0008883c0)
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/pkg/common-controller/groupsnapshot_controller_helper.go:319 +0x6c5
github.com/kubernetes-csi/external-snapshotter/v7/pkg/common-controller.(*csiSnapshotCommonController).updateGroupSnapshot(0xc00031ad00, 0xc0008883c0)
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/pkg/common-controller/groupsnapshot_controller_helper.go:247 +0x2a7
github.com/kubernetes-csi/external-snapshotter/v7/pkg/common-controller.(*csiSnapshotCommonController).syncGroupSnapshotByKey(0xc00031ad00, {0xc000058480, 0x1e})
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/pkg/common-controller/snapshot_controller_base.go:702 +0xb87
github.com/kubernetes-csi/external-snapshotter/v7/pkg/common-controller.(*csiSnapshotCommonController).groupSnapshotWorker(0xc00031ad00)
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/pkg/common-controller/snapshot_controller_base.go:647 +0xed
k8s.io/apimachinery/pkg/util/wait.BackoffUntil.func1(0x30?)
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/vendor/k8s.io/apimachinery/pkg/util/wait/backoff.go:226 +0x33
k8s.io/apimachinery/pkg/util/wait.BackoffUntil(0x0?, {0x1cc8900, 0xc0000f7290}, 0x1, 0xc0000ae540)
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/vendor/k8s.io/apimachinery/pkg/util/wait/backoff.go:227 +0xaf
k8s.io/apimachinery/pkg/util/wait.JitterUntil(0x0?, 0x0, 0x0, 0x0?, 0x0?)
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/vendor/k8s.io/apimachinery/pkg/util/wait/backoff.go:204 +0x7f
k8s.io/apimachinery/pkg/util/wait.Until(0x0?, 0x0?, 0x0?)
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/vendor/k8s.io/apimachinery/pkg/util/wait/backoff.go:161 +0x1e
created by github.com/kubernetes-csi/external-snapshotter/v7/pkg/common-controller.(*csiSnapshotCommonController).Run in goroutine 48
	/Users/leonardo.cecchi/go/src/github.com/kubernetes-csi/external-snapshotter/pkg/common-controller/snapshot_controller_base.go:234 +0x729

With this PR, the controller won't panic anymore, and an event will be recorder for the volumegroupsnapshot telling the user what happened:

➜ k get events |grep volumegroupsnapshot
13s         Warning   CreateGroupSnapshotContentFailed     volumegroupsnapshot/new-groupsnapshot-demo                 Cannot snapshot a non-CSI volume: pvc-de499b35-6856-4c52-98fc-74f3caa6ac27
42s         Warning   GroupSnapshotContentCreationFailed   volumegroupsnapshot/new-groupsnapshot-demo                 failed to create group snapshot content with error cannot snapshot a non-CSI volume for group snapshot default/new-groupsnapshot-demo: pvc-de499b35-6856-4c52-98fc-74f3caa6ac27

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Prevent snapshot controller from panicking when requesting a VolumeGroupSnapshot of a non-CSI volume.

[k8s-ci-robot]

Hi @leonardoce. Thanks for your PR.

I'm waiting for a kubernetes-csi member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[nixpanic]

Nice catch!

/lgtm
/ok-to-test

[nixpanic]

/unassign
/assign xing-yang

[xing-yang]

In the release note, can you change "external-snapshotter" to "snapshot controller"?

[leonardoce]

In the release note, can you change "external-snapshotter" to "snapshot controller"?

@xing-yang done. Thank you!

[xing-yang]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: leonardoce, xing-yang

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