Installing packages on an Alpine Linux based Docker image

What I learned today — 11 April 2018

Add packages to an Alpine based Docker image use the apk command:

RUN apk add --no-cache

Adding --no-cache helps to keep the image size to a minimum because it won’t keep a local copy of the package index.

One can also specify a specific version of a package to install:

RUN apk add --no-cache musl=1.1.19-r7