Blockchain for Image Digests

[amouat]

Ok, this one is out there and not intended to be done any time soon (or ever).

At the moment, image names included the address of the server the registry is running on, which isn't great. It would be better if we could ask any registry for an image, but then how do we know if the registry gives us the right (up-to-date) image? One way would be to have an blockchain that ties image names to digests. Then the image could be pulled from any registry and validated against the digest.