KEP-5007: DRA Device Attach Before Pod Scheduled

[KobayashiD27]

• One-line enhancement description: Some network- or fabric-attached devices need to be attached to a node before a pod using them can be scheduled.

• Issue link: DRA: attach devices to nodes #5007

• Other comments:

[k8s-ci-robot]

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[KobayashiD27]

@pohly
I have drafted the KEP. I would appreciate it if we could discuss it further.

[krmayankk]

I am new to this area of CDI, but would appreciate if we can show how this para is more tightly related to the proposal ? For example does this make it easier to attach requested resource directly to the node where the pod is about to be scheduled or some other example like https://cdi.liqid.com/hubfs/Inference-aaS-WP_FNL.pdf

[KobayashiD27]

In the current implementation, device attachment is executed by NodePrepareResource() after the Pod has been scheduled. However, if the device cannot be attached to the node at this stage, NodePrepareResource() will continue to fail, and the user will see the ContainerCreating state persist (internally, it will keep failing indefinitely). This issue is particularly problematic when fabric devices are shared across multiple Kubernetes clusters, as these clusters may compete for resources, leading to situations where device attachment fails.

Implementing this proposal will help avoid the persistent ContainerCreating state. By streamlining the process of attaching the requested resource directly to the node where the Pod is scheduled, the risk of device attachment failure is reduced. Consequently, this enhances the overall reliability of the system and prevents resource wastage.

[k8s-ci-robot]

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