Pass classpath plugins to tribe nodes

When testing tribe nodes in an integration test, we should pass the classpath
plugins of the node down to the tribe client nodes. Without this the tribe client
nodes could be prevented from communicating with the tribes.

core/src/main/java/org/elasticsearch/node/Node.java

@@ -315,7 +315,7 @@ public class Node implements Closeable {
             final ClusterService clusterService = new ClusterService(settings, settingsModule.getClusterSettings(), threadPool);
             clusterService.add(scriptModule.getScriptService());
             resourcesToClose.add(clusterService);
-            final TribeService tribeService = new TribeService(settings, clusterService, nodeEnvironment.nodeId());
+            final TribeService tribeService = new TribeService(settings, clusterService, nodeEnvironment.nodeId(), classpathPlugins);
             resourcesToClose.add(tribeService);
             final IngestService ingestService = new IngestService(settings, threadPool, this.environment,
                 scriptModule.getScriptService(), analysisModule.getAnalysisRegistry(), pluginsService.filterPlugins(IngestPlugin.class));

core/src/main/java/org/elasticsearch/tribe/TribeClientNode.java

@@ -24,13 +24,13 @@ import org.elasticsearch.env.Environment;
 import org.elasticsearch.node.Node;
 import org.elasticsearch.plugins.Plugin;
 
-import java.util.Collections;
+import java.util.Collection;
 
 /**
  * An internal node that connects to a remove cluster, as part of a tribe node.
  */
 class TribeClientNode extends Node {
-    TribeClientNode(Settings settings) {
+    TribeClientNode(Settings settings, Collection<Class<? extends Plugin>> classpathPlugins) {
-        super(new Environment(settings), Collections.<Class<? extends Plugin>>emptyList());
+        super(new Environment(settings), classpathPlugins);
     }
 }

core/src/main/java/org/elasticsearch/tribe/TribeService.java

@@ -58,10 +58,12 @@ import org.elasticsearch.env.Environment;
 import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.gateway.GatewayService;
 import org.elasticsearch.node.Node;
+import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.rest.RestStatus;
 import org.elasticsearch.transport.TransportSettings;
 
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.HashMap;
@@ -182,7 +184,8 @@ public class TribeService extends AbstractLifecycleComponent {
 
     private final List<Node> nodes = new CopyOnWriteArrayList<>();
 
-    public TribeService(Settings settings, ClusterService clusterService, final String tribeNodeId) {
+    public TribeService(Settings settings, ClusterService clusterService, final String tribeNodeId,
+                        Collection<Class<? extends Plugin>> classpathPlugins) {
         super(settings);
         this.clusterService = clusterService;
         Map<String, Settings> nodesSettings = new HashMap<>(settings.getGroups("tribe", true));
@@ -190,7 +193,7 @@ public class TribeService extends AbstractLifecycleComponent {
         nodesSettings.remove("on_conflict"); // remove prefix settings that don't indicate a client
         for (Map.Entry<String, Settings> entry : nodesSettings.entrySet()) {
             Settings clientSettings = buildClientSettings(entry.getKey(), tribeNodeId, settings, entry.getValue());
-            nodes.add(new TribeClientNode(clientSettings));
+            nodes.add(new TribeClientNode(clientSettings, classpathPlugins));
         }
 
         this.blockIndicesMetadata = BLOCKS_METADATA_INDICES_SETTING.get(settings).toArray(Strings.EMPTY_ARRAY);

qa/evil-tests/src/test/java/org/elasticsearch/tribe/TribeUnitTests.java

@@ -39,6 +39,7 @@ import org.junit.BeforeClass;
 
 import java.io.IOException;
 import java.nio.file.Path;
+import java.util.Collections;
 
 import static org.hamcrest.CoreMatchers.either;
 import static org.hamcrest.CoreMatchers.equalTo;
@@ -71,14 +72,14 @@ public class TribeUnitTests extends ESTestCase {
                 .put("cluster.name", "tribe1")
                 .put("node.name", "tribe1_node")
                     .put(NodeEnvironment.NODE_ID_SEED_SETTING.getKey(), random().nextLong())
-                .build()).start();
+                .build(), Collections.emptyList()).start();
         tribe2 = new TribeClientNode(
             Settings.builder()
                 .put(baseSettings)
                 .put("cluster.name", "tribe2")
                 .put("node.name", "tribe2_node")
                     .put(NodeEnvironment.NODE_ID_SEED_SETTING.getKey(), random().nextLong())
-                .build()).start();
+                .build(), Collections.emptyList()).start();
     }
 
     @AfterClass