Interoperability with sonatype nexus

[olfway]

I'm trying to run it against sonatype nexus docker repo, but unfortunately, it doesn't work

It prints warnings for every image
{"level":"warn","ts":1565175668.1175723,"caller":"client/client.go:86","msg":"error fetching manifest","repo":"somerepoy/some-image","tag":"2.8.2-50-ed92e4a4","error":"unexpected manifest schema was received from registry: application/vnd.docker.distribution.manifest.v1+json"}

[byxorna]

Thanks for reporting this @olfway! We do not use sonatype nexus for docker images internally. We depend on schemav1 manifests content types in https://github.com/nokia/docker-registry-client/blob/master/registry/manifest.go#L136, which maps to
application/vnd.docker.distribution.manifest.v1+prettyjws and
application/vnd.docker.distribution.manifest.v1+json. This is really odd, because your schema appears to match our accepted types! It is possible that the error is actually that the payload returned does not deserialize into schemav1.Manifest struct. Have you confirmed this works against a docker/distribution registry API endpoint?

[olfway]

I can try with the standard registry if needed, but the alternative project has a special flag to work with nexus: https://github.com/andrey-pohilko/registry-cli#nexus-docker-registry

[byxorna]

@olfway ah, interesting! Thanks for that - it is definitely unfortunate that the underlying client we use to talk to the registry does not surface more useful error messages. Do you have bandwidth to experiment with how to add support for the Nexus Registry? I currently do not have the time to look into this for a few weeks.

[olfway]

Unfortunately, I won't be able to use it without #4 anyway