Can not use build environment variables configured on docker hub builds

Docker Hub CI/CD
1

Hey guy’s

I’m trying to automate my build with the builds function on docker hub but now I’ve got a problem with the build env variables. I can’t access or use them in my Dockerfile.

I have configured several variables in the build section of my repository and would like to use them in my Dockerfile during the build.

Is this even possible?

Example:

I have configured a variable called “APP_VERSION” and a value (like 1.0 or something).

For debug purposes I’m exposing the variable by using echo like those example:

// not working
echo $APP_VERSION

// not working
echo ${APP_VERSION}

// not working
ENV APP_VERSION = ${APP_VERSION}
echo APP_VERSION

Unfortunately every echo is empty.

What am I doing wrong?