Make config layers in ociremote mountable #3741
Merged
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The wrapping that oci.Signatures does hides the ConfigLayer() implementation in remote.Image that remote.Write relies on for determining if it can mount the config blob (vs having to re-upload it), so remote.Write is sending additional blob uploads, which incurs an additional roundtrip that we don't really need to do.
Explicitly implement ConfigLayer() in the wrappers by dispatching to the wrapped implementation fixes this.
Before this change, this check fails due to the wrapping:
https://github.com/google/go-containerregistry/blob/1b4e4078a545f2b6f96766a064b45ee77cdbefdd/pkg/v1/partial/with.go#L102-L104
Which means we get back this fallback implementation: https://github.com/google/go-containerregistry/blob/1b4e4078a545f2b6f96766a064b45ee77cdbefdd/pkg/v1/partial/with.go#L52-L88
Which means this check fails: https://github.com/google/go-containerregistry/blob/1b4e4078a545f2b6f96766a064b45ee77cdbefdd/pkg/v1/remote/write.go#L364
So we didn't attempt to mount.
https://go.dev/play/p/2kW3-XbdjmM