How to customize official splunk universalforwarder docker image

[vrathore2016]

Below docker command will be used to run the app.

docker run \
-d \
-name app_x \
-v /opt/app/logs \
testapp
"/opt/app/logs" will be the place where app logs will be kept and sharing the data volume so that another container can access it.

I want to use another splunk container which will use the same data volume. Is there any official docker file from splunk?

I am stuck on how to implement this below on the splunk docker file.

[monitor:///home/ec2-user]
  whitelist=app\.log|\.log$|app
  index=test
  sourcetype=log4j
  [splunktcp://9997]
  compressed = false

OR set splunk_server_host

Thanks for helping