Multi-arch builds via Multi-Stage Dockerfile

[james-crowley]

I been digging through a couple of the issues/PRs pertaining multi-arch builds. It looks like #74 raised by @tianon was a good solution.

From reading the messages on the PR I am a confused as why it got closed. @davidswu or @dmcgowan care to weigh in on that? Was it because PR #81 and that the official Docker Images pipeline did not allow for multi-stage builds?

It looks like now that official Docker Images pipeline does now support multi-stage builds, docker-library/official-images#3383 (comment). @tianon can you confirm that?

If the official Docker Images pipeline does now support multi-stage builds, I would very much like to see this repository switch over to a multi-stage build. First stage would build the binaries and then the second stage would copy the binaries into the final container.

@yosifkit’s comment here, #83 (comment), makes a good point about not having the artifacts in the repository.

I would really like to see builds for s390x and ppc64le. Seems like I am not the only one either, #95, #73, and #74 (comment).

I think supporting multi-arch builds would be accomplished best by implementing a multi-stage Dockerfile.

[tianon]

I'd personally rather see these pre-compiled artifacts move to be official release artifacts attached to https://github.com/docker/distribution/releases/tag/v2.7.1, especially since that has broader usefulness outside of folks running the registry official image (and then this image simply becomes a consumer/packaging of the officially released upstream binaries).

[james-crowley]

@tianon Having the artifacts published on the releases would be great. If we get the binaries and the hashes, we pull them down and check them inside the Dockerfile. That is common design I see on the official Docker Images.

@dmcgowan Seems like you help with the releases, would you be open to publishing the binaries and hashes?

[james-crowley]

@tianon I opened a new PR based off your original PR. While I still would like to see the artifacts get uploaded to https://github.com/docker/distribution/releases/tag/v2.7.1, this provides an alternative way or at least a stop gap to hold us over until then.