While manually creating a manifest, it errors out multiple repositories currently not supported

[puneet-traceable]

I am trying to build multi-arch image but do not want to do this via qemu as the build become fairly slow if I use qemu.
Since this image building is happening inside github action, I am not able to use buildx builder and connect vm's for different architectures.
So, this is what I ended up doing:

1. Have runners for both amd64 and arm64
2. build and publish docker image for amd64 from amd64 runner(ghcr.io/puneet-work/images/gh-img-amd64:1.11.0)
3. build and publish docker image for arm64 from arm64 runner(ghcr.io/puneet-work/images/gh-img-arm64:1.11.0)
4. On amd64 runner create a manifest list
   docker buildx imagetools create -t ghcr.io/puneet-work/images/gh-img:1.11.0 --append ghcr.io/puneet-work/images/gh-img-arm64:1.11.0 --append ghcr.io/puneet-work/images/gh-img-amd64:1.11.0
   But this errors out with error
   error: multiple repositories currently not supported, found map[ghcr.io/puneet-work/images/gh-img:{} ghcr.io/puneet-work/images/gh-img-amd64:{} ghcr.io/puneet-work/images/gh-img-arm64:{}]

What would be the best way to achieve this. How does docker buildx build internally does it? And how can replicate the same manually?

[ciaranmcnulty]

Can you try making them different tags in the same repository?

i.e. ghcr.io/puneet-work/images/gh-img:1.11.0-arm64

[puneet-traceable]

@ciaranmcnulty I was specifically trying to keep image name different to avoid confusion.
How does it work when we do multi-arch builds with buildx? I do not see named tags when we do multi-arch build. I only see some digest there. Is there a way to replicate the same behaviour?

[ciaranmcnulty]

Not sure why the restriction is there TBH, was just trying to interpret the message

My understanding of multi-arch is that the manifest is pushed along with the layers for each (single-arch) image, but no tags are pushed that point directly to the images.

[tonistiigi]

This feature is being added in #1137

Registry scopes blobs by repo. They need to be uploaded again if the repo changes. If you use same repo and different tags then everything should work today.

[ciaranmcnulty]

As a suggestion maybe build and push the single-arch images into the main repo with tags that reflect the CI job number (eg :arm-ci-abc123456) to signal they're just there transiently, then either delete them explicitly or set your registry's tag cleanup policy to remove them later

[puneet-traceable]

@tonistiigi @ciaranmcnulty Is it possible to delete the single arch tags as the multi-arch manifest is already pointing to these one's?

[jedevc]

Feature added in #1137.