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 variable defaultValue and during the run command you can even update this value using --build-arg variable=value. To use these variables in the docker file you can refer them as $variable in run command.

Note: These variables would be available for Linux commands like RUN echo $variable and they wouldn't persist in the image.