bashbrew-arch   variants
amd64    jessie,jessie-slim,alpine,onbuild,stretch,stretch-slim
arm32v6  alpine
arm32v7  jessie,jessie-slim,onbuild,stretch,stretch-slim
arm64v8  alpine,onbuild,stretch,stretch-slim
i386     jessie,jessie-slim,alpine,onbuild,stretch,stretch-slim
ppc64le  alpine,onbuild,stretch,stretch-slim
s390x    alpine,onbuild,stretch,stretch-slim