initiliaze yarn clients in yarn app launcher so that a child class ca…

…n override the yarn client creation logic

gobblin-modules/gobblin-azkaban/src/main/java/org/apache/gobblin/azkaban/AzkabanGobblinYarnAppLauncher.java

@@ -80,7 +80,9 @@ public AzkabanGobblinYarnAppLauncher(String jobId, Properties gobblinProps)
 
   protected GobblinYarnAppLauncher getYarnAppLauncher(Config gobblinConfig)
       throws IOException {
-    return new GobblinYarnAppLauncher(gobblinConfig, this.yarnConfiguration);
+    GobblinYarnAppLauncher gobblinYarnAppLauncher = new GobblinYarnAppLauncher(gobblinConfig, this.yarnConfiguration);
+    gobblinYarnAppLauncher.initializeYarnClients(gobblinConfig);
+    return gobblinYarnAppLauncher;
   }
 
   /**

gobblin-yarn/src/main/java/org/apache/gobblin/yarn/GobblinYarnAppLauncher.java

@@ -157,6 +157,10 @@
  *   this count exceeds the maximum number allowed, it will initiate a shutdown.
  * </p>
  *
+ * <p>
+ *   Users of {@link GobblinYarnAppLauncher} need to call {@link #initializeYarnClients} which a child class can override.
+ * </p>
+ *
  * @author Yinan Li
  */
 public class GobblinYarnAppLauncher {
@@ -260,7 +264,6 @@ public GobblinYarnAppLauncher(Config config, YarnConfiguration yarnConfiguration
     YarnHelixUtils.setAdditionalYarnClassPath(config, this.yarnConfiguration);
     this.yarnConfiguration.set("fs.automatic.close", "false");
     this.originalYarnRMAddress = this.yarnConfiguration.get(GobblinYarnConfigurationKeys.YARN_RESOURCE_MANAGER_ADDRESS);
-    createPotentialYarnClients(config, this.potentialYarnClients);
 
     this.fs = GobblinClusterUtils.buildFileSystem(config, this.yarnConfiguration);
     this.closer.register(this.fs);
@@ -323,14 +326,14 @@ public GobblinYarnAppLauncher(Config config, YarnConfiguration yarnConfiguration
     }
   }
 
-  protected void createPotentialYarnClients(Config config, Map<String, YarnClient> potentialYarnClients) {
+  public void initializeYarnClients(Config config) {
     Set<String> potentialRMAddresses = new HashSet<>(ConfigUtils.getStringList(config, GobblinYarnConfigurationKeys.OTHER_YARN_RESOURCE_MANAGER_ADDRESSES));
     potentialRMAddresses.add(originalYarnRMAddress);
     for (String rmAddress : potentialRMAddresses) {
       YarnClient tmpYarnClient = YarnClient.createYarnClient();
       this.yarnConfiguration.set(GobblinYarnConfigurationKeys.YARN_RESOURCE_MANAGER_ADDRESS, rmAddress);
       tmpYarnClient.init(new YarnConfiguration(this.yarnConfiguration));
-      potentialYarnClients.put(rmAddress, tmpYarnClient);
+      this.potentialYarnClients.put(rmAddress, tmpYarnClient);
     }
   }
 
@@ -1069,6 +1072,8 @@ static Config addMetricReportingDynamicConfig(Config config, KafkaAvroSchemaRegi
   public static void main(String[] args) throws Exception {
     final GobblinYarnAppLauncher gobblinYarnAppLauncher =
         new GobblinYarnAppLauncher(ConfigFactory.load(), new YarnConfiguration());
+    gobblinYarnAppLauncher.initializeYarnClients(ConfigFactory.load());
+
     Runtime.getRuntime().addShutdownHook(new Thread() {
 
       @Override

gobblin-yarn/src/test/java/org/apache/gobblin/yarn/GobblinYarnAppLauncherTest.java

@@ -199,6 +199,7 @@ public void setUp() throws Exception {
         InstanceType.CONTROLLER, zkConnectionString);
 
     this.gobblinYarnAppLauncher = new GobblinYarnAppLauncher(this.config, clusterConf);
+    this.gobblinYarnAppLauncher.initializeYarnClients(this.config);
 
     this.configManagedHelix = ConfigFactory.parseURL(url)
         .withValue("gobblin.cluster.zk.connection.string",
@@ -213,6 +214,7 @@ public void setUp() throws Exception {
         InstanceType.PARTICIPANT, zkConnectionString);
 
     this.gobblinYarnAppLauncherManagedHelix = new GobblinYarnAppLauncher(this.configManagedHelix, clusterConf);
+    this.gobblinYarnAppLauncherManagedHelix.initializeYarnClients(this.configManagedHelix);
   }
 
   @Test