[SPARK-16080][YARN] Set correct link name for conf archive in executors.

This makes sure the files are in the executor's classpath as they're
expected to be. Also update the unit test to make sure the files are
there as expected.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #13792 from vanzin/SPARK-16080.

yarn/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMaster.scala

@@ -160,11 +160,17 @@ private[spark] class ApplicationMaster(
     }
 
     // Distribute the conf archive to executors.
-    sparkConf.get(CACHED_CONF_ARCHIVE).foreach { uri =>
-      val fs = FileSystem.get(new URI(uri), yarnConf)
+    sparkConf.get(CACHED_CONF_ARCHIVE).foreach { path =>
+      val uri = new URI(path)
+      val fs = FileSystem.get(uri, yarnConf)
       val status = fs.getFileStatus(new Path(uri))
-      setupDistributedCache(uri, LocalResourceType.ARCHIVE, status.getModificationTime().toString,
-        status.getLen.toString, LocalResourceVisibility.PRIVATE.name())
+      // SPARK-16080: Make sure to use the correct name for the destination when distributing the
+      // conf archive to executors.
+      val destUri = new URI(uri.getScheme(), uri.getRawSchemeSpecificPart(),
+        Client.LOCALIZED_CONF_DIR)
+      setupDistributedCache(destUri.toString(), LocalResourceType.ARCHIVE,
+        status.getModificationTime().toString, status.getLen.toString,
+        LocalResourceVisibility.PRIVATE.name())
     }
 
     // Clean up the configuration so it doesn't show up in the Web UI (since it's really noisy).

yarn/src/test/scala/org/apache/spark/deploy/yarn/YarnClusterSuite.scala

@@ -292,6 +292,14 @@ private object YarnClusterDriver extends Logging with Matchers {
       sc.stop()
     }
 
+    // Verify that the config archive is correctly placed in the classpath of all containers.
+    val confFile = "/" + Client.SPARK_CONF_FILE
+    assert(getClass().getResource(confFile) != null)
+    val configFromExecutors = sc.parallelize(1 to 4, 4)
+      .map { _ => Option(getClass().getResource(confFile)).map(_.toString).orNull }
+      .collect()
+    assert(configFromExecutors.find(_ == null) === None)
+
     // verify log urls are present
     val listeners = sc.listenerBus.findListenersByClass[SaveExecutorInfo]
     assert(listeners.size === 1)