How to pass arguments to a Dockerfile?

Question

I am using RUN instruction within a Dockerfile to install a rpm

RUN yum -y install samplerpm-2.3

However, I want to pass the value "2.3" as an argument. My RUN instruction should look something like:

RUN yum -y install samplerpm-$arg

where $arg=2.3

Answer 1

You are looking for --build-arg and the ARG instruction. These are new as of Docker 1.9. Check out https://docs.docker.com/engine/reference/builder/#arg. This will allow you to add ARG arg to the Dockerfile and then build with docker build --build-arg arg=2.3 ..