build arm64 images

We should be building arm64 images, not only amd64. It is also requested by mcr

Couple of other issues are linked to this one sort of.

I think the problem is related to some of these with the bugs that were reported. However, these issues are old and we may not face the same problems. Worth investigating.

Hi can someone help on how to approach this and go about this? I am a new contributor here

Porter's mission is to be a widely accessible cloud-native apps CLI, yet it doesn't support arm, that is widely used nowadays server- and clientside. This issue deserves more attention from core maintainers as it is directly correlated to the success of adopting Porter and CNAB.

From what I see, to make progress would be to add arm to these locations(?):

porter/magefile.go

Line 354 in 39d28db

err := shx.Command("docker", "build", "-t", img, "-f", "build/images/client/Dockerfile", ".").

porter/magefile.go

Line 367 in 39d28db

    
           err = shx.Command("docker", "build", "-t", img, "--build-arg", "PORTER_VERSION="+info.Version, "--build-arg", "REGISTRY="+registry, "-f", "build/images/agent/Dockerfile", ".").

all hard-coded mentions of architecture https://github.com/getporter/porter/tree/main/build/images

Go builds should use as already defaulted as ARGS by Docker BuildKit:

GOOS=${TARGETOS:-linux} GOARCH=${TARGETARCH} go build

Docker builds should add a platforms flag:

docker build --platform linux/amd64,linux/arm64 .