Merge pull request #721 from mikebridge/master

Add Proguard example to Custom Package Format documentation

src/sphinx/topics/custom.rst

@@ -13,7 +13,7 @@ SBT Assembly
     | Create a fat-jar with sbt-assembly in order to deliver a single,
     | self-containing jar as a package instead of the default lib/ structure
 
-First add the sbt-assembly plugin to your `plugins.sbt` file.
+First add the sbt-assembly plugin to your ``plugins.sbt`` file.
 
 .. code-block:: scala
 
@@ -53,6 +53,64 @@ contains the assembled jar. This is what the final ``build.sbt`` should contain:
 
     // the bash scripts classpath only needs the fat jar
     scriptClasspath := Seq( (jarName in assembly).value )
+
+
+Proguard
+-------------------
+
+    **Main Goal**
+
+    | Create a package that contains a single fat-jar that has been shrunken / optimized / obfuscated with `proguard <http://proguard.sourceforge.net/>`_.
+
+First add the `sbt-proguard <https://github.com/sbt/sbt-proguard>`_ plugin to
+the ``plugins.sbt`` file:
+
+.. code-block:: scala
+
+    addSbtPlugin("com.typesafe.sbt" % "sbt-proguard" % "0.2.2")
+
+Then configure the proguard options in ``build.sbt``:
+
+.. code-block:: scala
+
+    import com.typesafe.sbt.SbtProguard.ProguardKeys
+
+    // initialize the proguard settings
+    proguardSettings
+
+    // to configure proguard for scala, see
+    // http://proguard.sourceforge.net/manual/examples.html#scala
+    ProguardKeys.options in Proguard ++= Seq(
+        "--dontwarn scala.**",
+        "--dontwarn ch.qos.**"
+        // ...
+    )
+
+    // specify the entry point for a standalone app
+    ProguardKeys.options in Proguard += ProguardOptions.keepMain("com.example.Main")
+
+    // Java 8 requires a newer version of proguard than sbt-proguard's default
+    ProguardKeys.proguardVersion in Proguard := "5.2.1"
+    
+    // filter out jar files from the list of generated files, while
+    // keeping non-jar output such as generated launch scripts
+    mappings in Universal := (mappings in Universal).value.
+      filter {
+        case (file, name) =>  ! name.endsWith(".jar")
+      }
+
+    // ... and then append the jar file emitted from the proguard task to
+    // the file list
+    mappings in Universal ++= (ProguardKeys.proguard in Proguard).
+        value.map(jar => jar -> ("lib/" +jar.getName))
+
+    // point the classpath to the output from the proguard task
+    scriptClasspath := (ProguardKeys.proguard in Proguard).value.map(jar => jar.getName)
+
+Now when you package your project using a command such as ``sbt universal:package-zip-tarball``, 
+it will include fat jar that has been created by proguard rather than the normal 
+output in ``/lib``.
+
 
 Multi Module Builds
 -------------------