[SPARK-14245][WEB UI] Display the user in the application view

## What changes were proposed in this pull request?

The Spark UI (both active and history) should show the user who ran the application somewhere when you are in the application view. This was added under the Jobs view by total uptime and scheduler mode.

## How was this patch tested?

Manual testing

<img width="191" alt="username" src="https://cloud.githubusercontent.com/assets/13952758/14222830/6d1fe542-f82a-11e5-885f-c05ee2cdf857.png">

Author: Alex Bozarth <ajbozart@us.ibm.com>

Closes #12123 from ajbozarth/spark14245.

3 files changed, 10 insertions, 0 deletions

diff --git a/core/src/main/scala/org/apache/spark/ui/SparkUI.scala b/core/src/main/scala/org/apache/spark/ui/SparkUI.scala
index 6057522509..39155ff264 100644
--- a/core/src/main/scala/org/apache/spark/ui/SparkUI.scala
+++ b/core/src/main/scala/org/apache/spark/ui/SparkUI.scala
@@ -80,6 +80,10 @@ private[spark] class SparkUI private (
   }
   initialize()
 
+  def getSparkUser: String = {
+    environmentListener.systemProperties.toMap.get("user.name").getOrElse("<unknown>")
+  }
+
   def getAppName: String = appName
 
   def setAppId(id: String): Unit = {
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/AllJobsPage.scala b/core/src/main/scala/org/apache/spark/ui/jobs/AllJobsPage.scala
index d5f15f160b..07484c9550 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/AllJobsPage.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/AllJobsPage.scala
@@ -297,6 +297,10 @@ private[ui] class AllJobsPage(parent: JobsTab) extends WebUIPage("") {
         <div>
           <ul class="unstyled">
             <li>
+              <strong>User:</strong>
+              {parent.getSparkUser}
+            </li>
+            <li>
               <strong>Total Uptime:</strong>
               {
                 if (endTime < 0 && parent.sc.isDefined) {
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/JobsTab.scala b/core/src/main/scala/org/apache/spark/ui/jobs/JobsTab.scala
index 0d0e9b00d3..7b00b558d5 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/JobsTab.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/JobsTab.scala
@@ -31,6 +31,8 @@ private[ui] class JobsTab(parent: SparkUI) extends SparkUITab(parent, "jobs") {
   def isFairScheduler: Boolean =
     jobProgresslistener.schedulingMode == Some(SchedulingMode.FAIR)
 
+  def getSparkUser: String = parent.getSparkUser
+
   attachPage(new AllJobsPage(this))
   attachPage(new JobPage(this))
 }