Spark 1490 Add kerberos support to the HistoryServer

Here I've added the ability for the History server to login from a kerberos keytab file so that the history server can be run as a super user and stay up for along period of time while reading the history files from HDFS.

Author: Thomas Graves <tgraves@apache.org>

Closes #513 from tgravescs/SPARK-1490 and squashes the following commits:

e204a99 [Thomas Graves] remove extra logging
5418daa [Thomas Graves] fix typo in config
0076b99 [Thomas Graves] Update docs
4d76545 [Thomas Graves] SPARK-1490 Add kerberos support to the HistoryServer

core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala

@@ -75,6 +75,10 @@ class SparkHadoopUtil {
 
   def getSecretKeyFromUserCredentials(key: String): Array[Byte] = { null }
 
+  def loginUserFromKeytab(principalName: String, keytabFilename: String) { 
+    UserGroupInformation.loginUserFromKeytab(principalName, keytabFilename)
+  }
+
 }
 
 object SparkHadoopUtil {

core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala

@@ -22,6 +22,7 @@ import scala.collection.mutable
 import org.apache.hadoop.fs.{FileStatus, Path}
 
 import org.apache.spark.{Logging, SecurityManager, SparkConf}
+import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.scheduler._
 import org.apache.spark.ui.{WebUI, SparkUI}
 import org.apache.spark.ui.JettyUtils._
@@ -257,6 +258,7 @@ object HistoryServer {
   val STATIC_RESOURCE_DIR = SparkUI.STATIC_RESOURCE_DIR
 
   def main(argStrings: Array[String]) {
+    initSecurity()
     val args = new HistoryServerArguments(argStrings)
     val securityManager = new SecurityManager(conf)
     val server = new HistoryServer(args.logDir, securityManager, conf)
@@ -266,6 +268,20 @@ object HistoryServer {
     while(true) { Thread.sleep(Int.MaxValue) }
     server.stop()
   }
+
+  def initSecurity() {
+    // If we are accessing HDFS and it has security enabled (Kerberos), we have to login
+    // from a keytab file so that we can access HDFS beyond the kerberos ticket expiration.
+    // As long as it is using Hadoop rpc (hdfs://), a relogin will automatically
+    // occur from the keytab.
+    if (conf.getBoolean("spark.history.kerberos.enabled", false)) {
+      // if you have enabled kerberos the following 2 params must be set
+      val principalName = conf.get("spark.history.kerberos.principal")
+      val keytabFilename = conf.get("spark.history.kerberos.keytab")
+      SparkHadoopUtil.get.loginUserFromKeytab(principalName, keytabFilename)
+    }
+  }
+
 }
 
 

docs/monitoring.md

@@ -91,6 +91,30 @@ represents an application's event logs. This creates a web interface at
       The port to which the web interface of the history server binds.
     </td>
   </tr>
+  <tr>
+    <td>spark.history.kerberos.enabled</td>
+    <td>false</td>
+    <td>
+      Indicates whether the history server should use kerberos to login. This is useful
+      if the history server is accessing HDFS files on a secure Hadoop cluster. If this is 
+      true it looks uses the configs <code>spark.history.kerberos.principal</code> and
+      <code>spark.history.kerberos.keytab</code>. 
+    </td>
+  </tr>
+  <tr>
+    <td>spark.history.kerberos.principal</td>
+    <td>(none)</td>
+    <td>
+      Kerberos principal name for the History Server.
+    </td>
+  </tr>
+  <tr>
+    <td>spark.history.kerberos.keytab</td>
+    <td>(none)</td>
+    <td>
+      Location of the kerberos keytab file for the History Server.
+    </td>
+  </tr>
 </table>
 
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