How to set heap size for wildfly inside Docker container?

Question

I am trying to increase heap size for wildfly in docker container. This is easily done by updating wildfly/bin/standalone.conf in a regular wildfly setup.

Our base docker image for wildfly has a default heapsize of 512 MB which is required to be 1GB in one of the web apps. One way to go is by simple text replace in the Docker file using sed command -

RUN sed -i -- 's/JAVA_OPTS="-Xms64m -Xmx512m -XX:MaxPermSize=256m/JAVA_OPTS="-Xms2048m -Xmx6144m -XX:MaxPermSize=256m/g' /path/standalone.conf

I wanted to know if there's another (cleaner) way to solve this?

Answer 1

You can pass the value of the JAVA_OPTS environment variable in the command used to run the docker container:

docker run -it --env JAVA_OPTS="-server -Xms2048m -Xmx6144m -XX:MetaspaceSize=96M -XX:MaxMetaspaceSize=256m -Djava.net.preferIPv4Stack=true -Djboss.modules.system.pkgs=org.jboss.byteman -Djava.awt.headless=true" jboss/wildfly

Alternatively, you can extend the standard image by creating a Dockerfile containing:

FROM jboss/wildfly:latest

COPY standalone.conf $JBOSS_HOME/bin/

and placing your modified standalone.conf in the directory next to it.

Then you can build it:

docker build -t my/wildfly:latest .

and run it:

docker run my/wildfly