Sbt to download list of jars specified

Question

I have a list of JARs and I want to download the JARs via SBT into destination directory specified. Is there a way/command to do this?

What I am trying is to have a list of jars in classpath for an external system like spark. By default spark adds some jars to classpath and I also have some jars that my app depends on in addition to spark classpath jars.

I don't want to build a fat jar. And I need to package the dependent jars along with my jar in a tar ball.

My build.sbt

name := "app-jar"

scalaVersion := "2.10.5"

dependencyOverrides += "org.scala-lang" % "scala-library" % scalaVersion.value

scalacOptions ++= Seq("-unchecked", "-deprecation")

libraryDependencies += "org.apache.spark" %% "spark-streaming" % "1.4.1"

libraryDependencies += "org.apache.spark" %% "spark-core" % "1.4.1"

libraryDependencies += "org.apache.spark" %% "spark-streaming-kafka" % "1.4.1"


// I want these jars from here
libraryDependencies += "com.datastax.spark" %% "spark-cassandra-connector" % "1.4.0-M3"

libraryDependencies += "com.datastax.spark" %% "spark-cassandra-connector-java" % "1.4.0-M3"

libraryDependencies += "com.google.protobuf" % "protobuf-java" % "2.6.1"
...

// To here in my tar ball

So far I have achieved this using a shell script.

I want to know if there is a way to do the same with sbt .

Answer 1

Add sbt-pack to your project/plugins.sbt (or create it):

addSbtPlugin("org.xerial.sbt" % "sbt-pack" % "0.7.9")  

Add packAutoSettings to your build.sbt and then run:

sbt pack

In target/pack/lib you will find all jars (with dependencies).

Update

Add new task to sbt:

val libraries = Seq(
 "com.datastax.spark" %% "spark-cassandra-connector" % "1.4.0-M3",
 "com.datastax.spark" %% "spark-cassandra-connector-java" % "1.4.0-M3",
 "com.google.protobuf" % "protobuf-java" % "2.6.1"
)

libraryDependencies ++=  libraries


lazy val removeNotNeeded = taskKey[Unit]("Remove not needed jars")


removeNotNeeded := {
    val fileSet = libraries.map(l => s"${l.name}-${l.revision}.jar").toSet
    println(s"$fileSet")

    val ver = scalaVersion.value.split("\\.").take(2).mkString(".")
    println(s"$ver")    

    file("target/pack/lib").listFiles.foreach{
    file =>
    val without = file.getName.replace(s"_$ver","")
    println(s"$without")
    if(!fileSet.contains(without)){
               println(s"${file.getName} removed")
        sbt.IO.delete(file) 
    }
    }
}

After calling sbt pack call sbt removeNotNeeded . You will received only needed jar files.