Attacher reacts for deleted PVs if finalizer is present

[rfranzke]

What type of PR is this?
/kind bug

What this PR does / why we need it:
When a PersistentVolume gets deleted the external-attacher should consider it in case it has previously added its finalizer to it. Otherwise (for create/update operations), it can continue to only consider it if .spec.csi != nil.

Which issue(s) this PR fixes:
Fixes #217

Special notes for your reviewer:
NONE

Does this PR introduce a user-facing change?:

A bug that prevented the external-attacher from releasing its finalizer from a `PersistentVolume` object that was created using a legacy storage class provisioner has been fixed.

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[k8s-ci-robot]

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[rfranzke]

/assign @jsafrane
/assign @pohly
/assign @msau42

[jsafrane]

/ok-to-test

[jsafrane]

Thanks for the PR. I like it, however, can you please add an unit test for a migrated volume? Something like this, but with a migrated PV (so create migratedPVWithFinalizer()):

external-attacher/pkg/controller/csi_handler_test.go

Lines 1190 to 1199 in 9d2cafb

	{
	name: "VA deleted -> PV finalizer removed",
	initialObjects: []runtime.Object{pvDeleted(pvWithFinalizer())},
	deletedVA: va(false, "", nil),
	expectedActions: []core.Action{
	core.NewPatchAction(pvGroupResourceVersion, metav1.NamespaceNone, testPVName,
	types.MergePatchType, patch(pvDeleted(pvWithFinalizer()),
	pvDeleted(pv()))),
	},
	},

[jsafrane]

@rfranzke, are you still working on the fix? IMO it's very close to get merged.

[rfranzke]

Yes, sorry, I was busy the last days. I'll finish it tonight.

[rfranzke]

Can you please check again? I was not entirely sure what you meant with

can you please add an unit test for a migrated volume? Something like this, but with a migrated PV (so create migratedPVWithFinalizer()):

Do you consider a migrated PV a PV with the annotation? If so, how is it related to the change? Instead, I added three test cases for the finalizer removal, please check if this is what you meant.

[jsafrane]

I did not notice there already is gcePDPVWithFinalizer. You got it right :-).

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jsafrane, rfranzke

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[rfranzke]

Thanks for approving! Do you want me to open a cherry-pick PR for the release-2.1 branch?