How can I use a variable inside a Dockerfile CMD?

Question

Inside my Dockerfile:

ENV PROJECTNAME mytestwebsite
CMD [\"django-admin\", \"startproject\", \"$PROJECTNAME\"]

Error:

Comma         


        

Answer 1

If you want to use the value at runtime, set the ENV value in the Dockerfile. If you want to use it at build-time, then you should use ARG.

Example :

ARG value
ENV envValue=$value
CMD ["sh", "-c", "java -jar ${envValue}.jar"]

Pass the value in the build command:

docker build -t tagName --build-arg value="jarName"