HadoopSecurity should be a Singleton (#284)

* HadoopSecurity should be a singleton

* Update build to the last recognized successful deployment (Linkedin)

app/com/linkedin/drelephant/security/HadoopSecurity.java

@@ -41,13 +41,14 @@ public class HadoopSecurity {
   private static HadoopSecurity instance = null;
 
   public static HadoopSecurity getInstance() throws IOException{
-    if(instance==null) {
-      return new HadoopSecurity();
+    if (instance == null) {
+      instance = new HadoopSecurity();
     }
+
     return instance;
   }
 
-  public HadoopSecurity() throws IOException {
+  private HadoopSecurity() throws IOException {
     Configuration conf = new Configuration();
     UserGroupInformation.setConfiguration(conf);
     _securityEnabled = UserGroupInformation.isSecurityEnabled();

app/com/linkedin/drelephant/spark/fetchers/SparkLogClient.scala

@@ -43,7 +43,7 @@ class SparkLogClient(hadoopConfiguration: Configuration, sparkConf: SparkConf, e
 
   private val logger: Logger = Logger.getLogger(classOf[SparkLogClient])
 
-  private lazy val security: HadoopSecurity = new HadoopSecurity()
+  private lazy val security: HadoopSecurity = HadoopSecurity.getInstance()
 
   protected lazy val sparkUtils: SparkUtils = SparkUtils
 

app/org/apache/spark/deploy/history/SparkFSFetcher.scala

@@ -52,7 +52,7 @@ class SparkFSFetcher(fetcherConfData: FetcherConfigurationData) extends Elephant
   val eventLogUri = Option(fetcherConfData.getParamMap.get(LOG_LOCATION_URI_XML_FIELD))
   logger.info("The event log location of Spark application is set to " + eventLogUri)
 
-  private lazy val security = new HadoopSecurity()
+  private lazy val security = HadoopSecurity.getInstance()
 
   protected lazy val hadoopUtils: HadoopUtils = HadoopUtils
 

build.sbt

@@ -19,7 +19,7 @@ import Dependencies._
 
 name := "dr-elephant"
 
-version := "2.0.6"
+version := "2.0.13"
 
 organization := "com.linkedin.drelephant"