Support volume type "hostPath" for volume mounting

[vthurimella]

In what area(s)?

/area API

Describe the feature

Adding support for the "hostPath" volume type in Knative Serving would allow users to mount directories from the host node's filesystem into their Knative service containers. This feature would enable access to local storage on the node, facilitating use cases such as accessing node-specific data or utilizing local caches, while maintaining the serverless benefits of Knative.

[skonto]

Hi @vthurimella see comment here #13690 (comment).
Could you elaborate on this one? Is it an AI use case?

[vthurimella]

My use case involves scientific workflows with AI components. We use Knative as a dynamic resource allocator across a shared cluster. Our Knative tasks generate files that must be written to the specific node where execution occurs. We have a robust system for file tracking and inter-node file transfer. Without hostPath support, we cannot efficiently manage data locality, which is crucial for our workflow performance (right now we have the task call a file service on the execution node that has a hostPath mounted). This feature would significantly help me integrate Knative into my application.