csi: allow more than 1 writer claim for multi-writer mode #9040
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Fixes a bug where CSI volumes with the `MULTI_NODE_MULTI_WRITER` access mode were using the same logic as `MULTI_NODE_SINGLE_WRITER` to determine whether the volume had writer claims available for scheduling.
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| // the CSI spec doesn't allow for setting a max number of writers. | ||
| // we track node resource exhaustion through v.ResourceExhausted | ||
| // which is checked in WriteSchedulable | ||
| return true |
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That's a bit unfortunate - but it makes sense. Does it make sense to have an higher level/integration/e2e test to test the semantics?
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The reason it wasn't originally E2E tested was because very few CSI plugins actually allow this mode (typically on-prem solutions), so we can't feasibly do an E2E test for it. But we could probably add this dimension to one of the existing integration-style tests in the nomad package. Let me take a look at that.
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I dug into this a bit and that node resource exhaustion check isn't being made during the claim but during scheduling (in the feasibility checker), which in retrospect makes sense as we only validate arguments in an RPC and you can add resources to a cluster after the job submission has been made to make it feasible.
I've swapped one of the volumes in the existing feasibility checker tests to multiwriter and verified this code path is getting hit. I've also extended one of the existing RPC tests a bit to make sure the logic for ReadFreeClaims is being checked better while I'm in here. Our CSI E2E tests could use some work in general, but adding exhaustion checking would be a good idea for future work there.
…9040) Fixes a bug where CSI volumes with the `MULTI_NODE_MULTI_WRITER` access mode were using the same logic as `MULTI_NODE_SINGLE_WRITER` to determine whether the volume had writer claims available for scheduling. Extends CSI claim endpoint test to exercise multi-reader and make sure `WriteFreeClaims` is exercised for multi-writer in feasibility test.
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Fixes #8968
Fixes a bug where CSI volumes with the
MULTI_NODE_MULTI_WRITERaccess modewere using the same logic as
MULTI_NODE_SINGLE_WRITERto determine whetherthe volume had writer claims available for scheduling.