Perhaps we could simplify the Kubernetes charming workflow by delegating work to the charm store? If a charm specifies a resource as a URL, perhaps the charm store could download it instead of the charmer.
As a user, it’s impossible–or at least quite difficult–to inspect a charm and find its upstream location.
It’s important to note that the upstream-source field in metadata.yaml, while a helpful pointer for people reading the charm and trying to understand where the image came from, is not used by Juju, the charm, or any of the tooling. So it’s an informational hint only, and is also entirely optional.