Use "docker manifest" to publish multi-arch Docker images

[hakman]

Description

Multi-arch Docker images are very common these days and allow simplify Kubernetes manifests and deployments in general.
At the moment, flannel publishes the AMD64 image both as $REPO:$TAG and $REPO:$TAG-amd64. Instead of duplicating the AMD64 image, the $REPO:$TAG could be a Docker manifest.

This would allow to de-duplicate a lot the content of https://github.com/coreos/flannel/blob/v0.12.0/Documentation/kube-flannel.yml in a future PR.

Fixes: #1116

Todos

• Tests
• Documentation
• Release note

Release Note

Create multi-arch image instead of duplicating the AMD64 image

[rajatchopra]

Aha! Very useful. About time.
Will test and queue it up for merge.
Thanks.

[hakman]

Thanks @rajatchopra. I added a small extra to cover flannel-git also. Will send another PR to squash the flannel manifest later this week.

[electrocucaracha]

Hey there, I have a Kubespray's PR that is targeting to add Flannel Multi-Arch there but this change will definitely help on that. Hopefully this change gets merged soon.

[hakman]

@rajatchopra any chance this can make it into v0.13.0?

[Oats87]

LGTM

[hakman]

Thanks @rajatchopra :)