Images that can be built cross-architecture (build ARM images on the docker hub)
This uses the technique described in https://resin.io/blog/building-arm-containers-on-any-x86-machine-even-dockerhub/
Reference one of the cross-buildable base images, and then use cross-build-start and cross-build-end around your normal docker commands
FROM ma314smith/rpi2-python-qemu
RUN [ "cross-build-start" ]
// your normal docker commands
RUN [ "cross-build-end" ]