If you get this error E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing? at a apt-get step of your Dockerfile, try adding apt-get update above that step.

Most public Dockerfiles which you'll be inheriting from add rm -rf /var/lib/apt/lists after their apt-get install steps. This is to save space, we want our Docker images to be as minimal as possible. I don't know how much space it actually saves, but apt-get will cache install files in case you need to re-install quickly. When /var/lib/apt/lists is removed, there's some indexing that goes wacky and apt-get gets confused. You can easily reset it back to normal via apt-get update before attempting any installs. Don't listen to its --fix-missing advice: that won't fix your problem, just do an apt-get update.

So your Dockerfile might look like this:

FROM nvidia/cuda:10.1-cudnn7-runtime-ubuntu18.04
RUN apt-get update && \
    apt-get install -y wget && \
    rm -rf /var/lib/apt/lists  # follow their lead, create small/clean images