SPARK-1064

This reopens PR 649 from incubator-spark against the new repo

Author: Sandy Ryza <sandy@cloudera.com>

Closes #102 from sryza/sandy-spark-1064 and squashes the following commits:

270e490 [Sandy Ryza] Handle different application classpath variables in different versions
88b04e0 [Sandy Ryza] SPARK-1064. Make it possible to run on YARN without bundling Hadoop jars in Spark assembly

docs/building-with-maven.md

@@ -88,3 +88,9 @@ Running only java 8 tests and nothing else.
 Java 8 tests are run when -Pjava8-tests profile is enabled, they will run in spite of -DskipTests. 
 For these tests to run your system must have a JDK 8 installation. 
 If you have JDK 8 installed but it is not the system default, you can set JAVA_HOME to point to JDK 8 before running the tests.
+
+## Packaging without Hadoop dependencies for deployment on YARN ##
+
+The assembly jar produced by "mvn package" will, by default, include all of Spark's dependencies, including Hadoop and some of its ecosystem projects. On YARN deployments, this causes multiple versions of these to appear on executor classpaths: the version packaged in the Spark assembly and the version on each node, included with yarn.application.classpath.  The "hadoop-provided" profile builds the assembly without including Hadoop-ecosystem projects, like ZooKeeper and Hadoop itself. 
+
+

pom.xml

@@ -807,5 +807,51 @@
       </modules>
 
     </profile>
+    
+   <!-- Build without Hadoop dependencies that are included in some runtime environments. -->
+    <profile>
+      <id>hadoop-provided</id>
+      <activation>
+        <activeByDefault>false</activeByDefault>
+      </activation>
+      <dependencies>
+        <dependency>
+          <groupId>org.apache.hadoop</groupId>
+          <artifactId>hadoop-client</artifactId>
+          <scope>provided</scope>
+        </dependency>
+        <dependency>
+          <groupId>org.apache.hadoop</groupId>
+          <artifactId>hadoop-yarn-api</artifactId>
+          <scope>provided</scope>
+        </dependency>
+        <dependency>
+          <groupId>org.apache.hadoop</groupId>
+          <artifactId>hadoop-yarn-common</artifactId>
+          <scope>provided</scope>
+        </dependency>
+        <dependency>
+          <groupId>org.apache.hadoop</groupId>
+          <artifactId>hadoop-yarn-client</artifactId>
+          <scope>provided</scope>
+        </dependency>
+        <dependency>
+          <groupId>org.apache.avro</groupId>
+          <artifactId>avro</artifactId>
+          <scope>provided</scope>
+        </dependency>
+        <dependency>
+          <groupId>org.apache.avro</groupId>
+          <artifactId>avro-ipc</artifactId>
+          <scope>provided</scope>
+        </dependency>
+        <dependency>
+          <groupId>org.apache.zookeeper</groupId>
+          <artifactId>zookeeper</artifactId>
+          <scope>provided</scope>
+        </dependency>
+      </dependencies>
+    </profile>
+    
   </profiles>
 </project>

yarn/common/src/main/scala/org/apache/spark/deploy/yarn/ClientBase.scala

@@ -29,8 +29,10 @@ import org.apache.hadoop.fs._
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.io.DataOutputBuffer
 import org.apache.hadoop.mapred.Master
+import org.apache.hadoop.mapreduce.MRJobConfig
 import org.apache.hadoop.net.NetUtils
 import org.apache.hadoop.security.UserGroupInformation
+import org.apache.hadoop.util.StringUtils
 import org.apache.hadoop.yarn.api._
 import org.apache.hadoop.yarn.api.ApplicationConstants.Environment
 import org.apache.hadoop.yarn.api.protocolrecords._
@@ -379,9 +381,48 @@ object ClientBase {
 
   // Based on code from org.apache.hadoop.mapreduce.v2.util.MRApps
   def populateHadoopClasspath(conf: Configuration, env: HashMap[String, String]) {
-    for (c <- conf.getStrings(YarnConfiguration.YARN_APPLICATION_CLASSPATH)) {
+    val classpathEntries = Option(conf.getStrings(
+      YarnConfiguration.YARN_APPLICATION_CLASSPATH)).getOrElse(
+        getDefaultYarnApplicationClasspath())
+    for (c <- classpathEntries) {
       Apps.addToEnvironment(env, Environment.CLASSPATH.name, c.trim)
     }
+
+    val mrClasspathEntries = Option(conf.getStrings(
+      "mapreduce.application.classpath")).getOrElse(
+        getDefaultMRApplicationClasspath())
+    if (mrClasspathEntries != null) {
+      for (c <- mrClasspathEntries) {
+        Apps.addToEnvironment(env, Environment.CLASSPATH.name, c.trim)
+      }
+    }
+  }
+
+  def getDefaultYarnApplicationClasspath(): Array[String] = {
+    try {
+      val field = classOf[MRJobConfig].getField("DEFAULT_YARN_APPLICATION_CLASSPATH")
+      field.get(null).asInstanceOf[Array[String]]
+    } catch {
+      case err: NoSuchFieldError => null
+    }
+  }
+
+  /**
+   * In Hadoop 0.23, the MR application classpath comes with the YARN application
+   * classpath.  In Hadoop 2.0, it's an array of Strings, and in 2.2+ it's a String.
+   * So we need to use reflection to retrieve it.
+   */
+  def getDefaultMRApplicationClasspath(): Array[String] = {
+    try {
+      val field = classOf[MRJobConfig].getField("DEFAULT_MAPREDUCE_APPLICATION_CLASSPATH")
+      if (field.getType == classOf[String]) {
+        StringUtils.getStrings(field.get(null).asInstanceOf[String])
+      } else {
+        field.get(null).asInstanceOf[Array[String]]
+      }
+    } catch {
+      case err: NoSuchFieldError => null
+    }
   }
 
   def populateClasspath(conf: Configuration, sparkConf: SparkConf, addLog4j: Boolean, env: HashMap[String, String]) {