Advanced Configurations Example

Advanced Configurations Example

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Advanced Configurations Example

This is an example full build definition that demonstrates using Ivy configurations to group dependencies.

The utils module provides utilities for other modules. It uses Ivy configurations to group dependencies so that a dependent project doesn't have to pull in all dependencies if it only uses a subset of functionality. This can be an alternative to having multiple utilities modules (and consequently, multiple utilities jars).

In this example, consider a utils project that provides utilities related to both Scalate and Saxon. It therefore needs both Scalate and Saxon on the compilation classpath and a project that uses all of the functionality of 'utils' will need these dependencies as well. However, project a only needs the utilities related to Scalate, so it doesn't need Saxon. By depending only on the scalate configuration of utils, it only gets the Scalate-related dependencies.

   import sbt._
   import Keys._

object B extends Build 
{
   /********** Projects ************/

   // An example project that only uses the Scalate utilities.
   lazy val a = Project("a", file("a")) dependsOn(utils % "compile->scalate")

   // An example project that uses the Scalate and Saxon utilities.
   // For the configurations defined here, this is equivalent to doing dependsOn(utils),
   //  but if there were more configurations, it would select only the Scalate and Saxon
   //  dependencies.
   lazy val b = Project("b", file("b")) dependsOn(utils % "compile->scalate,saxon")

   // Defines the utilities project
   lazy val utils = Project("utils", file("utils")) settings(utilsSettings : _*)

   def utilsSettings: Seq[Setting[_]] =
        // Add the src/common/scala/ compilation configuration.
      inConfig(Common)(Defaults.configSettings) ++
        // Publish the common artifact
      addArtifact(artifact in (Common, packageBin), packageBin in Common) ++ Seq(
        // We want our Common sources to have access to all of the dependencies on the classpaths
        //   for compile and test, but when depended on, it should only require dependencies in 'common'
      classpathConfiguration in Common := CustomCompile,
        // Modify the default Ivy configurations.
        //   'overrideConfigs' ensures that Compile is replaced by CustomCompile
      ivyConfigurations ~= overrideConfigs(Scalate, Saxon, Common, CustomCompile),
        // Put all dependencies without an explicit configuration into Common (optional)
      defaultConfiguration := Some(Common),
        // Declare dependencies in the appropriate configurations
      libraryDependencies ++= Seq(
         "org.fusesource.scalate" % "scalate-core" % "1.5.0" % "scalate",
         "org.squeryl" %% "squeryl" % "0.9.4" % "scalate",
         "net.sf.saxon" % "saxon" % "8.7" % "saxon"
      )
   )

   /********* Configurations *******/

   lazy val Scalate = config("scalate") extend(Common) describedAs("Dependencies for using Scalate utilities.")
   lazy val Common = config("common") describedAs("Dependencies required in all configurations.")
   lazy val Saxon = config("saxon") extend(Common) describedAs("Dependencies for using Saxon utilities.")

     // Define a customized compile configuration that includes
     //   dependencies defined in our other custom configurations
   lazy val CustomCompile = config("compile") extend(Saxon, Common, Scalate)
}