AMBARI-18518 : Sinks should not try to read collector hosts from Zk if AMS is in embedded mode. (avijayan)

ambari-metrics/ambari-metrics-common/src/main/java/org/apache/hadoop/metrics2/sink/timeline/availability/MetricCollectorHAHelper.java

@@ -25,6 +25,7 @@ import org.apache.curator.RetryPolicy;
 import org.apache.curator.retry.BoundedExponentialBackoffRetry;
 import org.apache.curator.retry.RetryUntilElapsed;
 import org.apache.zookeeper.ZooKeeper;
+import org.apache.zookeeper.data.Stat;
 
 import java.util.Collection;
 import java.util.HashSet;
@@ -44,7 +45,8 @@ public class MetricCollectorHAHelper {
 
   private static final int CONNECTION_TIMEOUT = 2000;
   private static final int SESSION_TIMEOUT = 10000;
-  private static final String ZK_PATH = "/ambari-metrics-cluster/LIVEINSTANCES";
+  private static final String ZNODE = "/ambari-metrics-cluster";
+  private static final String ZK_PATH = ZNODE + "/LIVEINSTANCES";
   private static final String INSTANCE_NAME_DELIMITER = "_";
 
 
@@ -72,6 +74,12 @@ public class MetricCollectorHAHelper {
 
     try {
       client.start();
+      //Check if Znode exists
+      Stat stat = client.getZooKeeper().exists(ZNODE, false);
+      if (stat == null) {
+        LOG.info("/ambari-metrics-cluster znode does not exist. Skipping requesting live instances from zookeeper");
+        return collectors;
+      }
       liveInstances = RetryLoop.callWithRetry(client, new Callable<List<String>>() {
         @Override
         public List<String> call() throws Exception {

ambari-metrics/ambari-metrics-common/src/test/java/org/apache/hadoop/metrics2/sink/timeline/availability/MetricCollectorHATest.java

@@ -20,9 +20,13 @@ package org.apache.hadoop.metrics2.sink.timeline.availability;
 import com.google.gson.Gson;
 import junit.framework.Assert;
 import org.apache.commons.io.IOUtils;
+import org.apache.curator.CuratorZookeeperClient;
+import org.apache.curator.retry.BoundedExponentialBackoffRetry;
 import org.apache.hadoop.metrics2.sink.timeline.AbstractTimelineMetricsSink;
+import org.apache.zookeeper.ZooKeeper;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.powermock.api.easymock.PowerMock;
 import org.powermock.core.classloader.annotations.PrepareForTest;
 import org.powermock.modules.junit4.PowerMockRunner;
 import java.io.IOException;
@@ -34,13 +38,14 @@ import java.util.Arrays;
 import java.util.Collection;
 
 import static org.easymock.EasyMock.expect;
+import static org.easymock.EasyMock.expectLastCall;
 import static org.powermock.api.easymock.PowerMock.createNiceMock;
 import static org.powermock.api.easymock.PowerMock.expectNew;
 import static org.powermock.api.easymock.PowerMock.replayAll;
 import static org.powermock.api.easymock.PowerMock.verifyAll;
 
 @RunWith(PowerMockRunner.class)
-@PrepareForTest({AbstractTimelineMetricsSink.class, URL.class, HttpURLConnection.class})
+@PrepareForTest({AbstractTimelineMetricsSink.class, URL.class, HttpURLConnection.class, MetricCollectorHAHelper.class})
 public class MetricCollectorHATest {
 
   @Test
@@ -71,6 +76,33 @@ public class MetricCollectorHATest {
 
   }
 
+
+  @Test
+  public void testEmbeddedModeCollectorZK() throws Exception {
+
+
+    BoundedExponentialBackoffRetry retryPolicyMock = PowerMock.createMock(BoundedExponentialBackoffRetry.class);
+    expectNew(BoundedExponentialBackoffRetry.class, 1000, 10000, 1).andReturn(retryPolicyMock);
+
+    CuratorZookeeperClient clientMock = PowerMock.createMock(CuratorZookeeperClient.class);
+    expectNew(CuratorZookeeperClient.class, "zkQ", 10000, 2000, null, retryPolicyMock)
+      .andReturn(clientMock);
+
+    clientMock.start();
+    expectLastCall().once();
+
+    ZooKeeper zkMock = PowerMock.createMock(ZooKeeper.class);
+    expect(clientMock.getZooKeeper()).andReturn(zkMock).once();
+
+    expect(zkMock.exists("/ambari-metrics-cluster", false)).andReturn(null).once();
+
+    replayAll();
+    MetricCollectorHAHelper metricCollectorHAHelper = new MetricCollectorHAHelper("zkQ", 1, 1000);
+    Collection<String> liveInstances = metricCollectorHAHelper.findLiveCollectorHostsFromZNode();
+    verifyAll();
+    Assert.assertTrue(liveInstances.isEmpty());
+  }
+
   @Test
   public void findCollectorUsingKnownCollectorTest() throws Exception {
     HttpURLConnection connection = createNiceMock(HttpURLConnection.class);