Filter SPARK_HOME when submitting Spark jobs with Mesos cluster mode.

Author: tnachen

core/src/main/scala/org/apache/spark/deploy/rest/mesos/MesosRestServer.scala

@@ -94,7 +94,12 @@ private[mesos] class MesosSubmitRequestServlet(
     val driverMemory = sparkProperties.get("spark.driver.memory")
     val driverCores = sparkProperties.get("spark.driver.cores")
     val appArgs = request.appArgs
-    val environmentVariables = request.environmentVariables
+    // We don't want to pass down SPARK_HOME when launching Spark apps
+    // with Mesos cluster mode since it's populated by default on the client and it will
+    // cause spark-submit script to look for files in SPARK_HOME instead.
+    // We only need the ability to specify where to find spark-submit script
+    // which user can user spark.executor.home or spark.home configurations.
+    val environmentVariables = request.environmentVariables.filter(!_.equals("SPARK_HOME"))
     val name = request.sparkProperties.get("spark.app.name").getOrElse(mainClass)
 
     // Construct driver description

core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala

@@ -34,7 +34,7 @@ import org.apache.spark.util.Utils
 
 /**
  * Shared trait for implementing a Mesos Scheduler. This holds common state and helper
- * methods and Mesos scheduler will use.
+ * methods the Mesos scheduler will use.
  */
 private[mesos] trait MesosSchedulerUtils extends Logging {
   // Lock used to wait for scheduler to be registered