Container image virtual registry: handle file request service

🥅 Goal

This issue is for the handle request service that will be called in the container images virtual registry.

The main goal of that service is to execute this logic:

Is this requested file present in cache?
- Yes. Use the file referenced by the cache entry and return it.
- No. Use the upstream service to locate which upstream has the requested file and return a service response with workhorse instructions to use the dependency proxy logic on that url.
  - This requires #549104 (closed).

This service should mirror this service.

Other aspects that this service should handle:

user permissions. If possible cache them.
the cache validity period. In the Yes branch, if we're outside the cache validity period, we need to check with the related upstream (HEAD request) to make sure that the file in cache and on the upstream is the same.

Note: Internal event tracking will be added in #577685 (closed)

Take this opportunity to centralize the logic, functions or aspects with the Maven virtual registry objects.

Edited Oct 17, 2025 by Adie (she/her)