Building jars properly with sbt

Question

I have a map reduce .scala file like this:

import org.apache.spark._

object WordCount {
  def main(args: Array[String]){
    val inputDir = args(0)
    //val inputDir = "/Users/eksi/Desktop/sherlock.txt"
    val outputDir = args(1)
    //val outputDir = "/Users/eksi/Desktop/out.txt"
    val cnf = new SparkConf().setAppName("Example MapReduce Spark Job")

    val sc = new SparkContext(cnf)

    val textFile = sc.textFile(inputDir)
    val counts = textFile.flatMap(line => line.split(" "))
      .map(word => (word, 1))
      .reduceByKey(_ + _)
    counts.saveAsTextFile(outputDir)
    sc.stop()

  }
}

When I run my code, with setMaster("local[1]") parameters it works fine.

I want to put this code in a .jar and throw it to S3 to work with AWS EMR. Therefore, I use the following build.sbt to do so.

name := "word-count"

version := "0.0.1"

scalaVersion := "2.11.7"

// additional libraries
libraryDependencies ++= Seq(
  "org.apache.spark" % "spark-core_2.10" % "1.0.2"
)

It generates a jar file, however none of my scala code is in there. What I see is just a manifest file when I extract the .jar

When I run sbt package this is what I get:

[myMacBook-Pro] > sbt package
[info] Loading project definition from /Users/lele/bigdata/wordcount/project
[info] Set current project to word-count (in build file:/Users/lele/bigdata/wordcount/)
[info] Packaging /Users/lele/bigdata/wordcount/target/scala-2.11/word-count_2.11-0.0.1.jar ...
[info] Done packaging.
[success] Total time: 0 s, completed Jul 27, 2016 10:33:26 PM

What should I do to create a proper jar file that works like

WordCount.jar WordCount

Answer 1

Ref: It generates a jar file, however none of my scala code is in there. What I see is just a manifest file when I extract the .jar

Make sure your WordCount.scala is in the root or in src/main/scala

From http://www.scala-sbt.org/1.0/docs/Directories.html

Source code can be placed in the project's base directory as with hello/hw.scala. However, most people don't do this for real projects; too much clutter.

sbt uses the same directory structure as Maven for source files by default (all paths are relative to the base directory):