support a way to verify that all images are preresolved

[cppforlife]

Describe the problem/challenge you have

when applying a lock file that preresolves all images, it may be useful to verify that all found images by kbld have indeed been preresolved by the config. this would help finding problematic config (of images) before they get deployed to the cluster and potentially cannot be downloaded.

Describe the solution you'd like

add optional --expect-all-preresolved=bool flag (default false). can it be noun-ized further?

Anything else you would like to add:

n/a

[danielhelfand]

I think the feature sounds like a good safety measure for users. Just had a thought below.

So with this feature, I would have something like the following:

kbld -f manifest.yml -f /path/to/imageslock/images.yml --expect-all-preresolved

If the validation by kbld from --expect-all-preresolved succeeds, then I would expect to be able to immediately after pipe to kapp? Or if --expect-all-preresolved succeeds, I would get a confirmation message that all images are resolved or an error for failure?

Just mainly trying to see if this is intended to be more like a plan or dry run option. My thought is that is not what is being asked for, but just wanted to clarify.

[voor]

The intention is that this will provide an early warning mechanism for my use case, which is all images are relocated with kbld and a failure to identify an image being relocated is a guarantee that the next step in the "chain" will fail, most likely due to an Image Pull Failure. This would be leveraged in kapp-controller, so kapp would immediately follow kbld.

[danielhelfand]

Thanks @voor for the clarification on relocation/having kapp-controller as the driving use case.

[cppforlife]

If the validation by kbld from --expect-all-preresolved succeeds, then I would expect to be able to immediately after pipe to kapp

yup. if it fails it will fail, and kapp will receive 0 resources and error out as well.