Docker builds intermittently failing due to apt cache issues

[namliz]

This is a pretty well known problem.

Docker caches aggressively so a common first line in your Dockerfile like apt update will not run each time and eventually the mirror list will become stale and builds will fail.

Possible workaround #1

docker build --no-cache

Possible workaround #2

RUN apt-get clean && apt update

While the above helps with stale mirrors it does not help with unresponsive/slow/broken ones.

FROM debian:stable

RUN apt-get clean && apt update && apt install -y
RUN apt install -y kernel-package

This is taking a very long time today but eventually completes despite appearing to be frozen. Building large containers (this one ends up being 1GB in size, ouch) from a laptop is not a good workflow.