How to debug Payara Micro that runs in a Docker container?

Question

I'm running Payara Micro (payara/micro:5.2020.7) in a Docker container, but I'm not able to debug it.
This post explains that to debug it locally you need to run it using the command:

java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=9009 -jar payara-micro.jar app.war

I tried to run this command in the docker file but wasn't successful:

RUN true \
    && mv ${HOME_DIR}/setup/lib ${HOME_DIR}/lib \
    && java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=9009 -jar ${HOME_DIR}/payara-micro.jar

Has anybody been able to debug Payara Micro in Docker container?

Answer 1

It worked after adding the additional parameter to the docker file like below instead of part of RUN:

ENV JVM_ARGS=-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=9009

Because RUN is executed during the build process, where we want to add the parameter when the container is running.