How to define a variable in a Dockerfile?

Question

In my Dockerfile, I would like to define variables that I can use later in the Dockerfile.

I am aware of the

Answer 1

You can use ARG - see https://docs.docker.com/engine/reference/builder/#arg

The ARG instruction defines a variable that users can pass at build-time to the builder with the docker build command using the --build-arg = flag. If a user specifies a build argument that was not defined in the Dockerfile, the build outputs an error.