Craft does not correctly push multi arch images

[Dav1dde]

Environment

Running in Relay CI

Steps to Reproduce

Relay has a craft config which pushes docker containers. The source container is a multi arch container, the pushed container is not.

Expected Result

Craft should copy the multi arch container correctly.

Actual Result

The container is for a single arch. See also: getsentry/relay#3731

[BYK]

Sounds like we need a platforms config option for the docker target?

[Dav1dde]

The problem with multiarch images is, you need to build the manifest once and cant incrementally push single archs.
Which means a platforms option is most likely not going to work.

In Relay CI we use regctl to move/copy multiarch images, this would be a simple option and could be gated behind a multiarch: true option, to not always require the dependeny.

The alternative I believe is to rebuild the multiarch manifest with docker buildx imagetools, which still seems to be very experimental.