§The Build System

The Play build system is based on sbt, a minimally non-intrusive build tool for Scala and Java projects.

§The /project directory

All the build configuration is stored in the project directory. This folder contains 3 main files:

• build.properties: This is a marker file that describes the sbt version used.
• Build.scala: This is the application project build description.
• plugins.sbt: SBT plugins used by the project build.

Note that build.properties and plugins.sbt have to be manually updated when you are changing the play version.

§Default build for a Play 2.0 application

The default build description generated by the play new command looks like this:

import sbt._
import Keys._
import PlayProject._

object ApplicationBuild extends Build {

  val appName         = "Your application"
  val appVersion      = "1.0"

  val appDependencies = Seq(
    // Add your project dependencies here,
  )

  val main = PlayProject(
    appName, appVersion, appDependencies, mainLang = SCALA
  ).settings(
    // Add your own project settings here      
  )

}

It is written this way to make it easy to define standard options like application name, version and dependencies.

Note that every sbt feature is available in a Play 2.0 project.

§Play plugin for sbt

The Play console and all development features like live reloading are implemented via a sbt plugin. It is registred in the plugins.sbt file:

addSbtPlugin("play" % "sbt-plugin" % "2.0")

You might need to add the Typesafe repository in your list of resolvers, see : http://github.com/playframework/Play20/wiki/Repositories

§Adding dependencies and resolvers

Adding dependencies is simple:

val appDependencies = Seq(
  "group" % "name" % "version number",
)

So is adding resolvers:

val main = PlayProject(
  appName, appVersion, appDependencies, mainLang = SCALA
).settings(
  // Add custom repository: 
  resolvers += "Repository name" at "http://url.to/repository" 
)

Next: About SBT Settings