Build, Package, and Zip Up A Project With sbt

By request, I’m sharing a more of the sbt incantations that @stevej and I came up with last week when moving a project over from Ant/Ivy. We follow a pretty traditional Java packaging structure. Replicating that took a fair bit of experimentation, but we got it all working. This is what we ended up with in our sbt build file:

override def mainClass = Some("com.yourcompany.yourproject.Main")

/**
 * In the classpath:
 *  - all dependencies (via Ivy/Maven and in lib)
 *  - package classes
 * On the filesystem:
 *  - scripts
 *  - config
 */
def distPath = (
  // NOTE the double hashes (##) hoist the files in the preceeding directory
  // to the top level - putting them in the "base directory" in sbt's terminology
  ((outputPath ##) / defaultJarName) +++
  mainResources +++
  mainDependencies.scalaJars +++
  descendents(info.projectPath, "*.sh") +++
  descendents(info.projectPath, "*.rb") +++
  descendents(info.projectPath, "*.conf") +++
  descendents(info.projectPath / "lib" ##, "*.jar") +++
  descendents(managedDependencyRootPath / "compile" ##, "*.jar")
)

// creates a sane classpath including all JARs and populates the manifest with it
override def manifestClassPath = Some(
  distPath.getFiles
  .filter(_.getName.endsWith(".jar"))
  .map(_.getName).mkString(" ")
)

def distName = "yourproject-%s.zip".format(version)

lazy val zip = zipTask(distPath, "dist", distName) dependsOn (`package`) describedAs("Zips up the project.")

Some notes:

1. The file/path management stuff in sbt is a bit under-documented actually pretty well documented. We had to read a fair bit of source code to get the distPath built correctly. Particularly, “hoisting” files within the project tree to the top of the resulting directory was a bit of a trick.

2. Building a manifest that ends up in the resulting JAR for the project isn’t that hard: just pull together all the dependent JARs.

3. Our configuration includes a bunch of Ruby (generated Thrift code), shell scripts, and Configgy configuration files. You may not want to include these things, or even have them in your project.

4. You can swap out ZipTask for another compression format. I’d still suggest making your zip action dependent on packaging, which in turn will handle compilation.

Enjoy!