docker multiarch image - add ppc64le/s390x architectures to docker image

[grooverdan]

I was looking to use the distroless as a base for skydive (https://hub.docker.com/r/skydive/skydive/) on all architectures but it was only accessible on x86_64.

It seems bazel has a cross-compilation capability to make this happen.

Thanks the great contribution to container security.

[dlorenc]

We have no way to test images on these architectures, so I'm a bit hesitant to ship binaries for them. Would you be interested in forking/hosting your own binaries in a different project?

[grooverdan]

There is a travis os: linux-ppc64le for running builds/tests on real hardware. I've got an example multiarch builds/deployment with https://github.com/grooverdan/hello-world/ / https://travis-ci.org/grooverdan/hello-world.

If the package qemu-user-static (tested Fedora and Ubuntu) is installed on the running OS, and /usr/bin/qemu-${TARGET_GOARCH}-static is copied inside the container, then you can have a fully emulated hardware test container. I certainly understand if this doesn't meet the reassurance criteria.

I'm not yet ready to run my own project (first exposure to Bazel) yet but I'll probably get time eventually to hack on the dependencies (bazelbuild/rules_docker#300? / bazelbuild/bazel#5657? others?). I certainly can help out with testing (running/writing).

[donmccasland]

I'm not sure we can ever support this, but if someone wants to take a crack at it, I'm ready to review PRs and build results.

[mattmoor]

It should be relatively straightforward to add additional architectures following what I'm doing for arm64 here (and it's baseline changes): #586