[SPARK-9877] [CORE] Fix StandaloneRestServer NPE when submitting application

Detailed exception log can be seen in [SPARK-9877](https://issues.apache.org/jira/browse/SPARK-9877), the problem is when creating `StandaloneRestServer`, `self` (`masterEndpoint`) is null.  So this fix is creating `StandaloneRestServer` when `self` is available.

Author: jerryshao <sshao@hortonworks.com>

Closes #8127 from jerryshao/SPARK-9877.

1 files changed, 8 insertions, 8 deletions

diff --git a/core/src/main/scala/org/apache/spark/deploy/master/Master.scala b/core/src/main/scala/org/apache/spark/deploy/master/Master.scala
index 9217202b69..26904d39a9 100644
--- a/core/src/main/scala/org/apache/spark/deploy/master/Master.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/master/Master.scala
@@ -127,14 +127,8 @@ private[deploy] class Master(
 
   // Alternative application submission gateway that is stable across Spark versions
   private val restServerEnabled = conf.getBoolean("spark.master.rest.enabled", true)
-  private val restServer =
-    if (restServerEnabled) {
-      val port = conf.getInt("spark.master.rest.port", 6066)
-      Some(new StandaloneRestServer(address.host, port, conf, self, masterUrl))
-    } else {
-      None
-    }
-  private val restServerBoundPort = restServer.map(_.start())
+  private var restServer: Option[StandaloneRestServer] = None
+  private var restServerBoundPort: Option[Int] = None
 
   override def onStart(): Unit = {
     logInfo("Starting Spark master at " + masterUrl)
@@ -148,6 +142,12 @@ private[deploy] class Master(
       }
     }, 0, WORKER_TIMEOUT_MS, TimeUnit.MILLISECONDS)
 
+    if (restServerEnabled) {
+      val port = conf.getInt("spark.master.rest.port", 6066)
+      restServer = Some(new StandaloneRestServer(address.host, port, conf, self, masterUrl))
+    }
+    restServerBoundPort = restServer.map(_.start())
+
     masterMetricsSystem.registerSource(masterSource)
     masterMetricsSystem.start()
     applicationMetricsSystem.start()