Docker's build system is really strange. The build cache assumes that your dependency tree is linear, and it will invalidate the build cache if any file depende

Docker's build system is really strange. The build cache assumes that your dependency tree is linear, and it will invalidate the build cache if any file dependency changes, but a `RUN apt install foo` doesn't invalidate the cache--it's just assumed that every RUN statement is idempotent. Further, the Dockerfile's COPY is close to worthless--if you want to import all of your repo's Python packages, you have to put them all under a single directory or you have to copy them one by one (or you copy the whole repo and deal with the fact that every JS and README change will trigger a complete rebuild). Also, everything depends on a running Docker daemon and last I checked, the performance degraded if you tried to build multiple images in parallel.