Spark Framework + Kotlinで書いたGradleプロジェクトをHerokuにデプロイする ref: http://qiita.com/kenichi_odo/items/e266fbc8cf939feca8b0

file0.groovy

apply plugin: 'kotlin'
version '1.0-SNAPSHOT'

buildscript {
  ext.kotlin_version = '1.0.6'

  repositories {
    mavenCentral()
  }
  dependencies {
    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
  }
}

repositories {
  mavenCentral()
}

dependencies {
  compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
  compile 'com.sparkjava:spark-core:+'
  compile 'org.slf4j:slf4j-simple:+' // Failed to load classで怒られるので入れる
}

// ライブラリのコピー
task copyToLib(type: Copy) {
  into "$buildDir/libs"
  from(configurations.compile)
}

// Herokuから実行されるタスク
task stage(dependsOn: ['clean', 'build', 'copyToLib'])
build.mustRunAfter clean

file1.txt

web: java $JAVA_OPTS -cp build/classes/*:build/libs/* app.Main

file2.txt

package app

import spark.Spark
import spark.Spark.*


object Main {
  @JvmStatic fun main(args: Array<String>) {
    System.getenv("PORT")?.let {
      Spark.port(it.toInt())
    }
    get("/") { req, res -> "Hello World!" }
  }
}

file3.txt

.gradle
.idea
build