Fixing panic on layer pull as well as provide mechanism for auth

[sentientmonkey]

This fixes the panic on layer pull, as well as adding flags for accepting username and password. Since accepting username and password as a command line argument can be a concern on some systems, a prompt flag is provided to capture them over stdin.

Also happy to break these into separate PRs if you'd prefer.

[runcom]

not sure if this project is still active though, you may want to have a look at skopeo (github.com/projectatomic/skopeo) or its library github.com/containers/image

[sentientmonkey]

@dgonyeo @philips is this still a maintained project?

@runcom thanks - will check out skopeo - do you know if it provides pulling OCI images?

[runcom]

It doesn't right now but we're working on it

[sentientmonkey]

Is there any issue I can track or follow for that support?

Thanks for following up!

[runcom]

Is there any issue I can track or follow for that support?

unfortunately, that depends on having registries to serve OCI images. No registry out there, afaict, has that support. There's a WIP PR over at distribution/distribution#2076. You can follow that, and soon as something like that lands in the docker registry, we'll implement pulling OCI images from remote registries.

[sentientmonkey]

@runcom as a heads up, we have launched a registry that does support OCI images with our latest update to the EC2 Container Registry https://aws.amazon.com/about-aws/whats-new/2017/01/amazon-ecr-supports-docker-image-manifest-v2-schema-2/

I was able to test the code above against ECR and it works pulling down images.