How can I allow user to run Docker application with different arguments

Question

I have built a Docker image for my Java application - https://bitbucket.org/ijabz/songkongdocker/src/master/Dockerfile

The last line is

CMD /opt/songkong/songkongremote.sh

the (simplified) contents of songremote.sh are

#!/bin/sh
umask 000
./jre/bin/java-jar lib/songkong-6.9.jar -r

and it works fine.

However I have a customer who wants to run songkong with the -m option and a path

e.g

#!/bin/sh
umask 000
./jre/bin/java-jar lib/songkong-6.9.jar -m /users/music

1. So is there a way a single docker can allow for two different command to be run, or do I have to build another docker.

2. Either way how do I allow /users/music to be provided by user

The full contents of songkongremote are a bit more complicated, since more options have to be passed to Java

#!/bin/sh umask 000 ./jre/bin/java -XX:MaxRAMPercentage=60 -XX:MetaspaceSize=45 -Dcom.mchange.v2.log.MLog=com.mchange.v2.log.jdk14logging.Jdk14MLog -Dorg.jboss.logging.provider=jdk -Djava.util.logging.config.class=com.jthink.songkong.logging.StandardLogging -Dhttps.protocols=TLSv1.1,TLSv1.2 --add-opens java.base/java.lang=ALL-UNNAMED -jar lib/songkong-6.9.jar -r

Update I follows Cascaders answer and it has done something (look at Execution Command)

but songkong.sh is acting as if no parameters have been passed at all (rather than -r option passed).

songkong.sh (renamed from songkongremote.sh) now contains

#!/bin/sh
umask 000
./jre/bin/java  -XX:MaxRAMPercentage=60 -XX:MetaspaceSize=45 -Dcom.mchange.v2.log.MLog=com.mchange.v2.log.jdk14logging.Jdk14MLog -Dorg.jboss.logging.provider=jdk -Djava.util.logging.config.class=com.jthink.songkong.logging.StandardLogging -Dhttps.protocols=TLSv1.1,TLSv1.2 --add-opens java.base/java.lang=ALL-UNNAMED -jar lib/songkong-6.10.jar "$@"

and the end of Dockerfile is now

EXPOSE 4567

ENTRYPOINT ["/sbin/tini"]

# Config, License, Logs, Reports and Internal Database
VOLUME /songkong

# Music folder should be mounted here
VOLUME /music

WORKDIR /opt/songkong

ENTRYPOINT /opt/songkong/songkong.sh
CMD ["-r"]

I don't understand if okay that there are two entrypoints or the signifcance of the sbin/tini one

Answer 1

You may try to use ENTRY point for the command, and CMD only for arguments

ENTRYPOINT ["/sbin/tini", "/opt/songkong/songkongremote.sh" ]

CMD [] # Arguments are passed here

You also need to handle arguments in your .sh file:

#!/bin/sh
umask 000
./jre/bin/java-jar lib/songkong-6.9.jar "$@"

Answer 2

So is there a way a single docker can allow for two different command to be run, or do I have to build another docker.

Yes, you can handle this using single Dockerfile base on command with help of entrypoint.

entrypoint.sh

#!/bin/sh
umask 000
if [ "$1" == "-m" ];then
    echo "starting container with -m option"
    ./jre/bin/java-jar lib/songkong-6.9.jar "$@"
else
    ./jre/bin/java-jar lib/songkong-6.9.jar -r
fi

so if the docker run command look like this

docker run -it --rm myimage -m /users/music

it will execute first condition

But if [ "$1" == "-m" ] this will break if user pass like "-m /users/music" in double-quotes, as the condition only checking for first argument. you can adjust this accordingly.

So the Dockerfile will only contain entrypoint

ENTRYPOINT ["/opt/songkong/songkongremote.sh"]

Or you can CMD specify in Dockerfile

ENTRYPOINT ["/opt/songkong/songkongremote.sh"]
CMD ["-m", "/song/myfile]"

update:

You can not define two entrypoint per docker image, the first will be ignore.

Now to process to argument from CMD you should use array type syntax otherwise it will seems empty

ENTRYPOINT ["/opt/songkong/songkong.sh"]
CMD ["-r"]

Answer 3

You can switch to ENTRYPOINT instead of CMD. Your docker file will look like:

...
ENTRYPOINT [ "/opt/songkong/songkongremote.sh" ]
...

Your customers would then run your image as:

docker run img -r

or

docker run img -m /users/music

You can even alter your bash script to accept arguments and pass those arguments using the same method.

If you need to provide default arguments and the ability to override them on demand, the following approach will work:

Dockerfile:

...
ENTRYPOINT [ "/opt/songkong/songkongremote.sh" ]
CMD ["-r"]
...

Your modified script:

#!/bin/sh 
umask 000 
./jre/bin/java \
-XX:MaxRAMPercentage=60 \
-XX:MetaspaceSize=45 \
-Dcom.mchange.v2.log.MLog=com.mchange.v2.log.jdk14logging.Jdk14MLog \
-Dorg.jboss.logging.provider=jdk \
-Djava.util.logging.config.class=com.jthink.songkong.logging.StandardLogging \
-Dhttps.protocols=TLSv1.1,TLSv1.2 \
--add-opens java.base/java.lang=ALL-UNNAMED \
-jar lib/songkong-6.9.jar "$@"

Then, when customers run docker run img the CMD parameter will kick-in, but when they run docker run img -m /users/music the entrypoint command will be executed with the provided arguments.