Proxy Requests from coordinator to overlord

Add unit test and support https scheme

review comments

server/src/main/java/io/druid/server/http/OverlordProxyServlet.java

@@ -0,0 +1,67 @@
+/*
+ * Druid - a distributed column store.
+ * Copyright 2012 - 2015 Metamarkets Group Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.druid.server.http;
+
+import com.google.api.client.repackaged.com.google.common.base.Throwables;
+import com.google.inject.Inject;
+import com.metamx.common.ISE;
+import io.druid.client.indexing.IndexingService;
+import io.druid.client.selector.Server;
+import io.druid.curator.discovery.ServerDiscoverySelector;
+import org.eclipse.jetty.proxy.ProxyServlet;
+
+import javax.servlet.http.HttpServletRequest;
+import java.net.URI;
+import java.net.URISyntaxException;
+
+/**
+ * A Proxy servlet that proxies requests to the overlord.
+ */
+public class OverlordProxyServlet extends ProxyServlet
+{
+  private final ServerDiscoverySelector selector;
+
+  @Inject
+  OverlordProxyServlet(
+      @IndexingService ServerDiscoverySelector selector
+  )
+  {
+    this.selector = selector;
+  }
+
+  @Override
+  protected URI rewriteURI(HttpServletRequest request)
+  {
+    try {
+      final Server indexer = selector.pick();
+      if (indexer == null) {
+        throw new ISE("Cannot find instance of indexingService");
+      }
+      return new URI(
+          request.getScheme(),
+          indexer.getHost(),
+          request.getRequestURI(),
+          request.getQueryString(),
+          null
+      );
+    }
+    catch (URISyntaxException e) {
+      throw Throwables.propagate(e);
+    }
+  }
+}

server/src/test/java/io/druid/server/http/OverlordProxyServletTest.java

@@ -0,0 +1,50 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  Metamarkets licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.druid.server.http;
+
+import io.druid.client.selector.Server;
+import io.druid.curator.discovery.ServerDiscoverySelector;
+import junit.framework.Assert;
+import org.easymock.EasyMock;
+import org.junit.Test;
+
+import javax.servlet.http.HttpServletRequest;
+import java.net.URI;
+
+public class OverlordProxyServletTest
+{
+  @Test
+  public void testRewriteURI()
+  {
+    ServerDiscoverySelector selector = EasyMock.createMock(ServerDiscoverySelector.class);
+    Server server = EasyMock.createMock(Server.class);
+    EasyMock.expect(server.getHost()).andReturn("overlord:port");
+    EasyMock.expect(selector.pick()).andReturn(server).anyTimes();
+    HttpServletRequest request = EasyMock.createMock(HttpServletRequest.class);
+    EasyMock.expect(request.getScheme()).andReturn("https").anyTimes();
+    EasyMock.expect(request.getQueryString()).andReturn("param1=test&param2=test2").anyTimes();
+    EasyMock.expect(request.getRequestURI()).andReturn("/druid/overlord/worker").anyTimes();
+    EasyMock.replay(server, selector, request);
+
+    URI uri = new OverlordProxyServlet(selector).rewriteURI(request);
+    Assert.assertEquals("https://overlord:port/druid/overlord/worker?param1=test&param2=test2", uri.toString());
+  }
+
+}

services/src/main/java/io/druid/cli/CoordinatorJettyServerInitializer.java

@@ -21,6 +21,7 @@ import com.google.inject.Inject;
 import com.google.inject.Injector;
 import com.google.inject.servlet.GuiceFilter;
 import io.druid.server.coordinator.DruidCoordinatorConfig;
+import io.druid.server.http.OverlordProxyServlet;
 import io.druid.server.http.RedirectFilter;
 import io.druid.server.initialization.jetty.JettyServerInitUtils;
 import io.druid.server.initialization.jetty.JettyServerInitializer;
@@ -75,6 +76,7 @@ class CoordinatorJettyServerInitializer implements JettyServerInitializer
     // this will be removed in the next major release
     root.addFilter(GuiceFilter.class, "/coordinator/*", null);
 
+    root.addServlet(new ServletHolder(injector.getInstance(OverlordProxyServlet.class)), "/druid/indexer/*");
     HandlerList handlerList = new HandlerList();
     handlerList.setHandlers(new Handler[]{root});