cf push: support pushing from saved container image tarball

[rmcnew]

What's the user value of this feature request?

Users can push a container image without having to publish to a container registry. This is useful for testing or containers that contain non-public information.

Who is the functionality for?

Anyone who wants to cf push containers without publishing to a container registry.

How often will this functionality be used by the user?

I would use it daily. I am not sure how often other users would use it.

Who else is affected by the change?

I do not believe this would cause any breakage. It would allow containers to be pushed from a saved container image tarball in addition to container registries.

Is your feature request related to a problem? Please describe.

I'm always frustrated when I have to setup a container registry just to cf push a container-based app.

Describe the solution you'd like

cf push APP-NAME --docker-saved-image my_saved_app_image.tar

Describe alternatives you've considered

No viable alternatives. Container images must be deployed from container registries. This means the container must be published to a public registry or you must setup your own container registry. This is not ideal for testing or containers that have non-public data.

[a-b]

Thank you for your patience regarding the issue you reported. This seems like a significant feature as we must implement or repurpose existing components to act as an internal registry.

We will be reviewing your ticket with our product team to assess its impact and potential next steps. Once we have their feedback, we will update you accordingly.

If you have any further questions or additional information to share in the meantime, please feel free to reach out.

[krismarc]

I'd love this one. If implemented, I see space for still pulling from registry. However, only once and after staging it would be stored persistently as regular app. This would reduce risk if registry is somehow broken/unavailable. Currently if registry is down and application is restarted it would fail until registry is back.