Support GCR

[watiko]

GCR(Google Container Registry) is not supported by both Docker Registry Syncer and Docker Registry Tagger according to the README.

Is there any chance it will be supported?

[simoncochrane]

Hi watiko,

Yes, we plan to support GCR in the future. Given that GCR, Quay and Dockerhub all support the Docker V2 Registry API it makes sense to tick them all off with a common implementation.

Currently we are doing a major refactor and finalizing the container registry interfaces, at which point we can look at this.

[suneeta-mall]

Closing this in favour of https://github.com/nearmap/cvmanager/issues/15