Gradle minimal multi-projects scala build

README.md

Gradle multi-projects scala build

Assume that you have the following directory structure:

• your-app
  • project1
    • src
      • main
        • scala
          • App.scala
        • resources (optional)
      • test
  • project2
    • src
      • main
        • scala
          • App.scala
        • resources (optional)
      • test
  • settings.gradle
  • build.gradle

Enable Gradle wrapper (to allow users without gradle to use this project):

gradle wrapper

Edit settings.gradle:

/*
 * The settings file is used to specify which projects to include in your build.
 * 
 * Detailed information about configuring a multi-project build in Gradle can be found
 * in the user guide at https://docs.gradle.org/4.8.1/userguide/multi_project_builds.html
 */

rootProject.name = 'your-app-name'

include 'project1', 'project2'

Edit build.gradle:

def scalaVersion ='2.12'

// -------- DEPENDENCIES --------
// Sample dependencies
// def playJsonDep = "com.typesafe.play:play-json_$scalaVersion:2.6.9".toString()
// def jodaDep = 'org.joda:joda-convert:2.1'
// ------------------------------

// for scalaTest
buildscript {
    repositories {
        maven { url "https://plugins.gradle.org/m2/" }
    }
    dependencies {
        classpath "gradle.plugin.com.github.maiflai:gradle-scalatest:0.22"
    }
}

// define common properties/behaviour
//  (assume all sub projects are scala)
subprojects {
    apply plugin: 'scala'
    apply plugin: 'application'
    apply plugin: "com.github.maiflai.scalatest" // for scalaTest

    group 'your-app-name'
    version '0.1'

    repositories {
        jcenter()
        mavenCentral()
//        maven { url "https://dl.bintray.com/akka/snapshots/" }
    }

    dependencies {
        compile "org.scala-lang:scala-library:$scalaVersion".toString()
        // compile 'log4j:log4j:1.2.17'

        testCompile "org.scalatest:scalatest_$scalaVersion:3.0.5".toString()
        testRuntime 'org.pegdown:pegdown:1.4.2' // for scalaTest
    }

    // copy dependencies to build/dependencies
    task copyDeps(type: Copy) {
        from configurations.runtime
        into 'build/dependencies'
    }

    // run copyDeps before jar...
    jar.dependsOn copyDeps
}

// project specific
project(':project1') {
    mainClassName = "project1.App"

    dependencies {
        // compile akkaStreamKafkaDep
    }

    jar {
        manifest {
            attributes 'Main-Class': 'project1.App'
        }
    }
}

project(':project2') {
    mainClassName = "project2.App"

    dependencies {
        // compile akkaStreamKafkaDep
        // compile akkaStreamHBaseDep
        // compile playJsonDep
    }

    jar {
        manifest {
            attributes 'Main-Class': 'project2.App'
        }
    }
}

Compilation using gradle:

./gradlew clean test jar

This will run the following tests: clean, test, jar.

This will create the following files:

• ./project1/build/libs/project1-0.1.jar : main jar
• ./project1/build/dependencies : project1 dependencies (.jar)
• ./project2/build/libs/project2-0.1.jar : fake producer main jar
• ./project12/build/dependencies : project2 dependencies (.jar)

To run a project1/2 use:

./gradlew :project1:run

or (if the above doesn't work)

java -cp ./project1/build/lib/*:./project1/build/libs/* \
    project1r.App

See also: https://docs.gradle.org/current/userguide/multi_project_builds.html

This really helped me a lot to upgrade an older Scala project to a more recent Gradle version; thanks! :)