csi: missing plugins during node delete are not an error

[tgross]

Fixes #8121

When deregistering a client, CSI plugins running on that client may not get a
chance to fingerprint before being stopped. Account for the case where a
plugin allocation is the last instance of the plugin and has been deleted from
the state store to avoid errors during node deregistration.

[langmartin]

Doublecheck: the alloc was already GC'd, which is what deleted the plugin. After the alloc is already gone, the final fingerprint CSIInfo is sent to the server. There's no other race in play?

[tgross]

Doublecheck: the alloc was already GC'd, which is what deleted the plugin. After the alloc is already gone, the final fingerprint CSIInfo is sent to the server. There's no other race in play?

The original report didn't have a lot of detail and the person seems to have abandoned the issue, but that's what looks like happened. The fingerprint happens on the node fingerprint timer (every 30s IIRC, which is also the cause of #7296), whereas the plugin cleanup for the allocs happens immediately.

[drewbailey]

Should this have a changelog entry?

[tgross]

It's in #8620

[drewbailey]

My mistake, thanks!

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