I think this looks great! However, I am concerned about always having to specify any additional gradle opts on the command line. Personally, I would like to have the ability to persist and version control the options in addition to providing them on the command line. Persisting the options would reduce tribal knowledge and/or additional scripts required to build functions.

This could be achieved by moving the gradle.properties file into the function folder and adding a command to the Dockerfile to move it into the root project folder before building, e.g.:

...
COPY . /home/app/
RUN if [ -f /home/app/function/gradle.properties ] ; then mv /home/app/function/gradle.properties /home/app/gradle.properties ; fi
RUN gradle build
...

If you want to ensure that org.gradle.daemon=false is always specified, you could instead append a function-local gradle.properties file to the gradle.properties file in the root build folder.

This approach would continue to work with the --build-arg change you have already made. What do you think?

I like your suggestion, as I'm not an experienced Java programmer. I'll try it and see to add it to the PR.

Can you explain this a little more to me, please:

If you want to ensure that org.gradle.daemon=false is always specified, you could instead append a function-local gradle.properties file to the gradle.properties file in the root build folder.

Absolutely! I apologize for not being clear in my previous comment. All I mean is that you could replace:

RUN if [ -f /home/app/function/gradle.properties ] ; then mv /home/app/function/gradle.properties /home/app/gradle.properties ; fi

with

RUN if [ -f /home/app/function/gradle.properties ] ; then cat /home/app/function/gradle.properties >> /home/app/gradle.properties ; fi

in my previous example. This would ensure that the gradle.properties file you created in this PR would always be used (org.gradle.daemon=false), and that anything a dev added in a gradle.properties file with their function (like proxy settings) would be appended to it.

Sorry this PR has become inactive, I'm going to close. Feel free to raise a new one if required to cover java11, java11-vert-x and so forth. cc @pmlopes