Just a simple example how Dockers compose works.

The project contains a "Gradle project" which have a task called BuildCopy which just copy it's build.gradle to the Dockers /test directory.

This /test dir is mapped to the hosts outputVolume which is accessible for other services as well.

The second service (printService) will just look into the shared outputVolume and then print the content of the build.gradle.

Run it with

docker-compose up

It will generate the outputVolume which will then contain the build.gradle file.