Update Dockerfile to support multiple architectures

[gcoon151]

The umoci was hard coded to amd64. Diversifying the dockerfile. Disclaimer: I haven't tested this yet. Just wanted to put a proposal out here.

- Description of the problem which is fixed/What is the use case
s390 team noticed daemonset install container had resources that wouldn't run on s390.

- What I did
Added a TARGETARCH to specify platform.

- How to verify it
build container and run on different platforms.

- Description for the changelog
expand daemonset installer container to support s390x, ppc64le, arm64 (beyond the original amd64)

[openshift-ci]

Hi @gcoon151. Thanks for your PR.

I'm waiting for a github.com member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[gkurz]

This might be okay for now but we'll have to get umoci from an official image in the RH repository when we go GA.

[gcoon151]

My searches turned up empty for an official umoci from RH. Happy to update with wherever we want to pull that from.

[littlejawa]

I had a look, there is no packaging.
I think there are two ways out of it:

• pre-fetch the binaries themselves, from the github repo (which means declaring each binary with path and checksum, and let the CI job pull them before the build starts)
• build umoci as part of the container image build

I didn't dig to search for alternatives, those are the most obvious. We can decide what option we take when we get to it.