Gradle Play multi module template

A very simple skeleton of a Play application for Gradle, in which some modules can be included/excluded programmatically, and injected into Play framework.

Usage scenario

Sometimes, your Gradle project is composed of different modules that live in the same repo and, depending on some properties set at compile time, you want to enable/disable some modules from the final build.

Here's a very simple multi-module Play project in which you can add few optional libs, and inject them into a controller.

Besides the Play application, located in the app folder, there are three modules:

• api, which contains a simple trait called BaseTrait
• lib_one, which depends on api and contains few implementation of BaseTrait
• lib_two, which depends on api and lib_one, and contains few implementation of BaseTrait

How to build and run the project

./gradlew runPlayBinary

and then open a browser to http://localhost:9000. If everything went good, you will see the message

Traits found in classpath: 5

and, in the console

from DerivedFive
from DerivedFour
from DerivedTwo
from DerivedOne
from DerivedThree > from DerivedOne

last line is not a typo (see the implementation of DerivedThree).

Toggle inclusion of lib_one and/or lib_two

You can replace the dependencies in the project build.gradle

play project(":lib_one")
play project(":lib_two")

with

play project(":lib_${project.property('profile_lib')}")

and then build and run, for example, with

./gradlew runPlayBinary -Pprofile_lib=two

to enable only lib_two.