`Accept:` header is missing `application/vnd.docker.distribution.manifest.v2+json`

[tianon]

https://github.com/cue-labs/oci/blob/14751940d5b22f24e01c024cc61a3138565f8c7e/ociregistry/ociclient/client.go#L216-L227

This is missing application/vnd.docker.distribution.manifest.v2+json, which means doing lookups on a registry which has funky Accept: behavior (like, say, Docker Hub) doesn't correctly fetch images built with docker build (classic, not buildkit/buildx) / pushed with docker push (without the new containerd integration enabled).

I'm sure there are better examples, but the image I was testing and have handy is winamd64/hello-world:nanoserver-ltsc2022 -- see https://explore.ggcr.dev/?image=winamd64/hello-world:nanoserver-ltsc2022

Without adding application/vnd.docker.distribution.manifest.v2+json in that block of code I've linked above, I get Hub's automatically downgraded application/vnd.docker.distribution.manifest.v1+prettyjws manifest instead, but it works fine when I add it (at first I thought it was the order of that list, but have confirmed it's just the entries missing the Docker v2 type).

[tianon]

(I also have no idea what application/vnd.docker.container.image.v1+json is, but it's not hurting anything being there :smile:)

[tianon]

Ah that's the image config for the example I linked -- probably doesn't need to be in the Accept list, especially since it's only used for fetching manifests:

https://github.com/cue-labs/oci/blob/14751940d5b22f24e01c024cc61a3138565f8c7e/ociregistry/ociclient/client.go#L235-L240

[mvdan]

cc @rogpeppe

[rogpeppe]

@tianon Thanks very much for the report! Should be fixed by https://review.gerrithub.io/c/cue-labs/oci/+/1176474.