Provide admission server builds for CPU architectures other than amd64

[hbagdi]

What would you like to be added:

Admission server builds are currently only available for amd64 architecture.
We should provide builds for other architectures as well.

Why is this needed:
Our users could be running k8s clusters on other CPU architectures.

[hbagdi]

For some context, #621 was the first attempt to get an image built and published. We decided to take an incremental approach to building out our images. There is no blocker for building docker images for other CPU architectures.

[youngnick]

/good-first-issue

Outstanding work here is to update our webhook admission build to some other architectures, linux/arm64 for certain, and to make sure we can add more if needed.

[k8s-ci-robot]

@youngnick:
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In response to this:

/good-first-issue

Outstanding work here is to update our webhook admission build to some other architectures, linux/arm64 for certain, and to make sure we can add more if needed.

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[akankshakumari393]

/assign

[akankshakumari393]

Quick question -

1. what all arch do we want to add? I have already added ard64 and arm64 .
2. All arch images need to use to repo that has arch information in its name, earlier we were using ${REGISTRY}/admission-server:${VERSION_TAG}. Now it should be ${REGISTRY}/admission-server-${ARCH}:${VERSION_TAG}. So do we need to create new repo or is it handled by infra team.

[youngnick]

I think that amd64 and arm64 are probably okay for now, we can add more later if required.

I didn't know that was a requirement, maybe we can check with some other things like ingress-nginx as to how they handle this (I don't think that other Kubernetes projects have the arch in the repo name?)

[shaneutt]

We now have a multi-arch build with new arm64 support:

https://console.cloud.google.com/gcr/images/k8s-staging-gateway-api/global/admission-server@sha256:5dd8c42658daeb0a26ba0e4ac5e33c3bba2f1f4cd0f41685f837dd4a3684d2f0/details?tab=pull