Docker will hopefully solve this with new Dockerfile syntax soon. A proposal to do that has been bouncing around[0] -- even a working implementation or two in

Docker will hopefully solve this with new Dockerfile syntax soon. A proposal to do that has been bouncing around[0] -- even a working implementation or two in forks -- but they haven't settled on a final design direction yet. [0] https://github.com/docker/docker/issues/7115 https://github.com/docker/docker/issues/7115