Managing config (and secrets) in Docker builds
Accessing private repositories in Docker builds. — As of Docker 18.09 there is a much cleaner, natively supported way to achieve what this (and other) workarounds were doing. See https://medium.com/@tonistiigi/build-secrets-and-ssh-forwarding-in-docker-18-09-ae8161d066 for details. Fitting the pieces together for a smooth, automated and reliable continuous integration or delivery pipeline is hard.