ggcr: Expected error when parsing name reference that is an Image ID

[picatz]

Describe the bug

The name.ParseReference function treats a local "Image ID" reference as a name.Tag, instead of returning an error.

To Reproduce

imageID := "sha256:0505a58fa4646ca8c19699d99a1053c789d00d9424ee9d8ed4d988e7642d1672"

name, err := name.ParseReference(imageID)
// err is nil, name is a tag

registry := name.Context().RegistryStr()
// "index.docker.io"

repo := name.Context().RepositoryStr()
// "library/sha256"

tag := name.Context().Tag(name.Identifier()).TagStr()
// "0505a58fa4646ca8c19699d99a1053c789d00d9424ee9d8ed4d988e7642d1672"

Expected behavior

I would expect name.ParseReference to return an error.

Additional context

The "Image ID" is a valid local image reference that can be run with docker run, but not something we can pull from a registry, because it's neither a tag or digest.

📃 Click for more details demonstrating the difference between "Image ID", "Image Digest", and "Image Tag".

We have an ubuntu:latest image pulled, with sha256:77906da… as the (remote) image digest, and sha256:2b7cc08… as the local image ID.

$ docker images --digests --no-trunc
REPOSITORY       TAG       DIGEST            IMAGE ID          CREATED         SIZE
ubuntu           latest    sha256:77906da…   sha256:2b7cc08…   2 months ago    69.2MB
…

We can run our ubuntu:latest image by specifying the same digest we have locally:

$ docker run --rm -it ubuntu@sha256:77906da…
root@69a36beaf024:/# exit

Of course, we cannot specify that image ID as the digest, because it's not the same thing:

$ docker run --rm -it ubuntu@sha256:2b7cc08…
Unable to find image 'sha256:2b7cc08…' locally
docker: Error response from daemon: manifest for ubuntu@sha256:2b7cc08…  not found: manifest unknown: manifest unknown.
See 'docker run --help'.

We can specify just the Image ID of our local ubuntu:latest:

$ docker run --rm -it sha256:2b7cc08…     
root@c29f22dc1dd9:/# exit

Then, just for fun, we can't specify just the digest, because the daemon won't know which image you're referring to:

$ docker run --rm -it sha256:77906da…
docker: Error response from daemon: No such image: 
sha256:77906da…
See 'docker run --help'.