Let a data plane own Programmed on network interfaces

[scotwells]

NSO seeds Programmed=Unknown on a NetworkInterface and its claim and then leaves it alone, because the component that realizes the interface owns it. A VPC attachment controller is about to become that component. This confirms NSO will not fight it, and corrects the enhancement's account of how an attachment comes into being.

NSO does not overwrite an external writer, on any path. seedProgrammed and its NetworkInterface equivalent both write only when the condition is absent, and every other write is field-scoped on a freshly read object — nothing assigns status wholesale, and nothing touches status.vpc or status.attachmentRef. That holds through a requeue, a rejection (which demotes only Ready, and Bound/Allocated for a claim that never bound), and a release-and-rebind under reclaimPolicy: Retain. No fix was needed; two regression tests now lock the behaviour in so a future status write cannot quietly clobber the data plane's report.

Docs. "Reaching the data plane" said the agent on the node creates the VPCAttachment from the interface. That direction cannot work: the CNI configuration the attachment produces has to exist before the pod's sandbox is created, so an attachment that only appears as a result of the attach is too late to cause one. The section and its diagram now describe the realized design — the infrastructure provider writes the spec before the pod, the node reports status — and state explicitly which three status fields NSO never writes and never clears.

RBAC. Added networkinterface-dataplane-role, alongside the per-CRD helper roles this repo already ships: read on interfaces and claims, status write on both. The definition belongs here because the resources do; binding it to a specific service account is a deployment concern and stays in infra.

One observation left alone, worth a decision elsewhere: under Retain, an interface released back to Available keeps whatever Programmed the data plane last reported, even though nothing is attached. Clearing it would make NSO a writer of a condition it deliberately does not own, so the stale value is the data plane's to correct.

make lint clean, internal/controller envtest suite green.

Related

Programmed is the condition #164's contract leaves to whoever realizes the interface. This confirms NSO will not overwrite an external writer, and locks that in with tests. The first writer is the VPC controller in datum-cloud/cloud#6.

datum-cloud/compute#112 is the consumer end: the address and its conditions surface on Instance.status.

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