Use docker buildx in CI to build containers for other architectures (including ARM)

[toddbaert]

With the increasing populariry of both OpenFeature and M1 Macs/ARM in general, we should do multi-arch container builds. All containers built as part of this demo should be able to run on x86 and ARM.

This was partially started and then abandoned. See here.

[PrateekKumar1709]

@toddbaert I would like to work on this issue. Can you please assign this to me?

[beeme1mr]

Sure @PrateekKumar1709, thanks for help!

[PrateekKumar1709]

Hi @beeme1mr,

Upon reviewing the current CI workflow, I noticed that multi-architecture builds are already enabled using Docker Buildx and QEMU, supporting both amd64 and arm64 platforms as required. This means the containers are already being built for these architectures without any additional changes needed for this aspect.

Optimization: To improve the efficiency of the build process, I suggest introducing Docker build caching. This would reduce the build times by reusing layers from previous builds, especially when there are no significant changes. The caching can be done by adding the cache-from and cache-to parameters in the Docker build steps, like this:

cache-from: type=gha
cache-to: type=gha,mode=max

This addition can help to speed up repeated builds in CI by utilizing GitHub Actions caching.

Please let me know if this seems like a good approach to you and I can raise a PR, thanks.