Images for ARM

[mpiscaer]

All OpenStack images built for Atmosphere are multi-architecture builds.

I appreciate that the digest hashes of the images are included in _atmosphere_images, as this ties each Atmosphere release to the exact image used. However, the downside is that the digest hash always points to the amd64 variant of the image. This becomes a problem when deploying OpenStack on ARM-based systems, because the referenced image does not match the required architecture.

I can use the Tag name main or 2023.2 but the I lose the relation of the Atmosphere release and image.

[mnaser]

I dug into our pinning tool (cmd/pinimages/pinimages.go). GetImageDigest calls NewImageSource with an empty SystemContext, so containers/image resolves the manifest list to the host platform (defaulting to linux/amd64). We then hash that per-arch manifest, which is why _atmosphere_images ends up with the amd64 digest instead of the multi-arch manifest digest.

Fix: fetch the manifest list digest instead of a platform-resolved manifest—e.g., set DockerManifestListSelection/DockerDisablePlatformSelection in the SystemContext (or otherwise ensure GetManifest returns the top-level list). That will store the multi-arch digest and keep release-to-image mapping intact for both amd64 and arm64.