Packaging and Running Scala Spark Project with Maven - scala

Question

I am writing an application in Scala that uses Spark. I am packaging the app using Maven and running into problems when constructing an "uber" or "fat" jar.
The problem I am facing is that running the application works fine inside of an IDE or if I provide a non-uber-jar'd version of the dependencies as the java class path, but it does not work if I give the uber jar as the class path, i.e.
java -Xmx2G -cp target/spark-example-0.1-SNAPSHOT-jar-with-dependencies.jar debug.spark_example.Example data.txt
does not work. I get the following error message:
ERROR SparkContext: Error initializing SparkContext.
com.typesafe.config.ConfigException$Missing: No configuration setting found for key 'akka.version'
at com.typesafe.config.impl.SimpleConfig.findKey(SimpleConfig.java:124)
at com.typesafe.config.impl.SimpleConfig.find(SimpleConfig.java:145)
at com.typesafe.config.impl.SimpleConfig.find(SimpleConfig.java:151)
at com.typesafe.config.impl.SimpleConfig.find(SimpleConfig.java:159)
at com.typesafe.config.impl.SimpleConfig.find(SimpleConfig.java:164)
at com.typesafe.config.impl.SimpleConfig.getString(SimpleConfig.java:206)
at akka.actor.ActorSystem$Settings.<init>(ActorSystem.scala:168)
at akka.actor.ActorSystemImpl.<init>(ActorSystem.scala:504)
at akka.actor.ActorSystem$.apply(ActorSystem.scala:141)
at akka.actor.ActorSystem$.apply(ActorSystem.scala:118)
at org.apache.spark.util.AkkaUtils$.org$apache$spark$util$AkkaUtils$$doCreateActorSystem(AkkaUtils.scala:122)
at org.apache.spark.util.AkkaUtils$$anonfun$1.apply(AkkaUtils.scala:54)
at org.apache.spark.util.AkkaUtils$$anonfun$1.apply(AkkaUtils.scala:53)
at org.apache.spark.util.Utils$$anonfun$startServiceOnPort$1.apply$mcVI$sp(Utils.scala:1991)
at scala.collection.immutable.Range.foreach$mVc$sp(Range.scala:160)
at org.apache.spark.util.Utils$.startServiceOnPort(Utils.scala:1982)
at org.apache.spark.util.AkkaUtils$.createActorSystem(AkkaUtils.scala:56)
at org.apache.spark.rpc.akka.AkkaRpcEnvFactory.create(AkkaRpcEnv.scala:245)
at org.apache.spark.rpc.RpcEnv$.create(RpcEnv.scala:52)
at org.apache.spark.SparkEnv$.create(SparkEnv.scala:247)
at org.apache.spark.SparkEnv$.createDriverEnv(SparkEnv.scala:188)
at org.apache.spark.SparkContext.createSparkEnv(SparkContext.scala:267)
at org.apache.spark.SparkContext.<init>(SparkContext.scala:424)
at debug.spark_example.Example$.main(Example.scala:9)
at debug.spark_example.Example.main(Example.scala)
I would really appreciate help understanding what I need to add to the pom.xml file and why I need to add it to get this to work.
I have searched online and found the following resources, which I tried (see in the pom), but could not get to work:
1) Spark User Mailing list: http://apache-spark-user-list.1001560.n3.nabble.com/Packaging-a-spark-job-using-maven-td5615.html
2) how to package spark scala application
I have a simple example that demonstrates this problem, a simple 1 class project (src/main/scala/debug/spark_example/Example.scala):
package debug.spark_example
import org.apache.spark.{SparkConf, SparkContext}
object Example {
def main(args: Array[String]): Unit = {
val sc = new SparkContext(new SparkConf().setAppName("Test").setMaster("local[2]"))
val lines = sc.textFile(args(0))
val lineLengths = lines.map(s => s.length)
val totalLength = lineLengths.reduce((a, b) => a + b)
lineLengths.foreach(println)
println(totalLength)
}
}
Here is the pom.xml file:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>debug.spark-example</groupId>
<artifactId>spark-example</artifactId>
<version>0.1-SNAPSHOT</version>
<inceptionYear>2015</inceptionYear>
<properties>
<scala.majorVersion>2.11</scala.majorVersion>
<scala.minorVersion>.2</scala.minorVersion>
<spark.version>1.4.1</spark.version>
</properties>
<repositories>
<repository>
<id>scala-tools.org</id>
<name>Scala-Tools Maven2 Repository</name>
<url>http://scala-tools.org/repo-releases</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>scala-tools.org</id>
<name>Scala-Tools Maven2 Repository</name>
<url>http://scala-tools.org/repo-releases</url>
</pluginRepository>
</pluginRepositories>
<dependencies>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>${scala.majorVersion}${scala.minorVersion}</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_${scala.majorVersion}</artifactId>
<version>${spark.version}</version>
</dependency>
</dependencies>
<build>
<sourceDirectory>src/main/scala</sourceDirectory>
<plugins>
<plugin>
<groupId>org.scala-tools</groupId>
<artifactId>maven-scala-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-eclipse-plugin</artifactId>
<configuration>
<downloadSources>true</downloadSources>
<buildcommands>
<buildcommand>ch.epfl.lamp.sdt.core.scalabuilder</buildcommand>
</buildcommands>
<additionalProjectnatures>
<projectnature>ch.epfl.lamp.sdt.core.scalanature</projectnature>
</additionalProjectnatures>
<classpathContainers>
<classpathContainer>org.eclipse.jdt.launching.JRE_CONTAINER</classpathContainer>
<classpathContainer>ch.epfl.lamp.sdt.launching.SCALA_CONTAINER</classpathContainer>
</classpathContainers>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.4</version>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>attached</goal>
</goals>
</execution>
</executions>
<configuration>
<tarLongFileMode>gnu</tarLongFileMode>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.2</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<minimizeJar>false</minimizeJar>
<createDependencyReducedPom>false</createDependencyReducedPom>
<artifactSet>
<includes>
<!-- Include here the dependencies you want to be packed in your fat jar -->
<include>*:*</include>
</includes>
</artifactSet>
<filters>
<filter>
<artifact>*:*</artifact>
<excludes>
<exclude>META-INF/*.SF</exclude>
<exclude>META-INF/*.DSA</exclude>
<exclude>META-INF/*.RSA</exclude>
</excludes>
</filter>
</filters>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>reference.conf</resource>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.7</version>
<configuration>
<skipTests>true</skipTests>
</configuration>
</plugin>
</plugins>
</build>
<reporting>
<plugins>
<plugin>
<groupId>org.scala-tools</groupId>
<artifactId>maven-scala-plugin</artifactId>
</plugin>
</plugins>
</reporting>
</project>
Many thanks in advance for your help.

Answer 1

It seems that the Spark submit script must be used to run the program.
Rather than:
java -Xmx2G -cp target/spark-example-0.1-SNAPSHOT-jar-with-dependencies.jar debug.spark_example.Example data.txt
Do something like:
<path-to>/spark-1.4.1/bin/spark-submit --class debug.spark_example.Example --master local[2] target/spark-example-0.1-SNAPSHOT-jar-with-dependencies.jar data.txt
It also seems to work without the shaded jar; with only the jar-with-dependencies. The following pom.xml file worked for me:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>debug.spark-example</groupId>
<artifactId>spark-example</artifactId>
<version>0.1-SNAPSHOT</version>
<inceptionYear>2015</inceptionYear>
<properties>
<scala.majorVersion>2.11</scala.majorVersion>
<scala.minorVersion>.2</scala.minorVersion>
<spark.version>1.4.1</spark.version>
</properties>
<repositories>
<repository>
<id>scala-tools.org</id>
<name>Scala-Tools Maven2 Repository</name>
<url>http://scala-tools.org/repo-releases</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>scala-tools.org</id>
<name>Scala-Tools Maven2 Repository</name>
<url>http://scala-tools.org/repo-releases</url>
</pluginRepository>
</pluginRepositories>
<dependencies>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>${scala.majorVersion}${scala.minorVersion}</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_${scala.majorVersion}</artifactId>
<version>${spark.version}</version>
</dependency>
</dependencies>
<build>
<sourceDirectory>src/main/scala</sourceDirectory>
<plugins>
<plugin>
<groupId>org.scala-tools</groupId>
<artifactId>maven-scala-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-eclipse-plugin</artifactId>
<configuration>
<downloadSources>true</downloadSources>
<buildcommands>
<buildcommand>ch.epfl.lamp.sdt.core.scalabuilder</buildcommand>
</buildcommands>
<additionalProjectnatures>
<projectnature>ch.epfl.lamp.sdt.core.scalanature</projectnature>
</additionalProjectnatures>
<classpathContainers>
<classpathContainer>org.eclipse.jdt.launching.JRE_CONTAINER</classpathContainer>
<classpathContainer>ch.epfl.lamp.sdt.launching.SCALA_CONTAINER</classpathContainer>
</classpathContainers>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.4</version>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>attached</goal>
</goals>
</execution>
</executions>
<configuration>
<tarLongFileMode>gnu</tarLongFileMode>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.7</version>
<configuration>
<skipTests>true</skipTests>
</configuration>
</plugin>
</plugins>
</build>
<reporting>
<plugins>
<plugin>
<groupId>org.scala-tools</groupId>
<artifactId>maven-scala-plugin</artifactId>
</plugin>
</plugins>
</reporting>
</project>

Answer 2

This may have something to do with the order of your maven plugins. You're using both the "maven-assembly-plugin" and "maven-shade-plugin" plugins in your project, both bound to the same phase in the maven lifecycle. When this happens, maven executes the plugins in the order that they appear in the plugins section, so in your case it executes the assembly plugin, then the shade plugin.
Based on the output jar you're trying to run and the shade transformation you have, you probably want the opposite order. However, you may not even need the assembly plugin for your use case. You might be able to use the target/spark-example-0.1-SNAPSHOT-shaded.jar file.
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<!-- SNIP -->
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<!-- SNIP -->
</plugin>
</plugins>

Answer 3

Akka Docs helped me fix the issue. If you are using Shade then you must specify a transformer
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>reference.conf</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<manifestEntries>
<Main-Class>akka.Main</Main-Class>
</manifestEntries>
</transformer>