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

Late to the party, but if you don't want to expose environment variables, I guess it's easier to do something like this:

RUN echo 1 > /tmp/__var_1
RUN echo `cat /tmp/__var_1`
RUN rm -f /tmp/__var_1

I ended up doing it because we host private npm packages in aws codeartifact:

RUN aws codeartifact get-authorization-token --output text > /tmp/codeartifact.token
RUN npm config set //company-123456.d.codeartifact.us-east-2.amazonaws.com/npm/internal/:_authToken=`cat /tmp/codeartifact.token`
RUN rm -f /tmp/codeartifact.token

And here ARG cannot work and i don't want to use ENV because i don't want to expose this token to anything else