I had a working dockerfile, but I wanted to upgrade it so that the container would not run from the root user. Here is the initial version of the dockerfile:

FROM something/openjdk-17:1.13-1

WORKDIR /opt/app

COPY ./build/libs/*.jar app.jar

CMD java ${JAVA_OPTS:- -Xmx1G} -jar app.jar

Then, I tried to add a user, grant him rights and run the container on his behalf.

FROM something/openjdk-17:1.13-1

RUN adduser -D trmonbs && chown -R trmonbs /opt/app
WORKDIR /opt/app

COPY ./build/libs/*.jar app.jar

USER trmonbs
CMD java ${JAVA_OPTS:- -Xmx1G} -jar app.jar

However, I got:

The command '/bin/sh -c adduser -D trmonbs && chown -R trmonbs /opt/app' returned a non-zero code: 2
Process exited with code 2

What could be the problem?