Harbor: Proxy cache expanded support for additional registries

[xaleeks]

Support harbor acting as pull through cache for more registries beyond harbor and Dockerhub. continuation of https://github.com/goharbor/harbor/issues/11658

[liangminhua]

please support docker registry

[ChristianCiach]

We have a local docker registry that is based on the image library/registry:2 from docker hub. If I lie to Harbor and configure this registry using "Provider: Harbor", the resulting proxy-cache seems to work just fine.

[xaleeks]

@ChristianCiach I'm not sure I understand, what do you mean by 'based on the image from docker hub'. You are configuring a dockerhub endpoint as a harbor type endpoint?

[ChristianCiach]

@xaleeks No, a "dockerhub endpoint" can only download images from docker hub (meaning docker.io). What I am trying to say is that we are using a private registry that is based on this image: https://hub.docker.com/_/registry

To use harbor as a proxy cache for our private registry that is based on this image, I can configure a "harbor endpoint" in harbor, pointing it to our private registry, and it seems to work just fine.

[xaleeks]

That sounds correct then, since Harbor is just running docker distribution on the inside.

[xaleeks]

I'm expecting GCR, Quay.io, ECR, ACR in that order of importance. Let me know if you disagree @steven-zou @stonezdj