YARN-6476. Advanced Federation UI based on YARN UI v2. (#5920) Contributed by Shilun Fan.

Reviewed-by: Inigo Goiri <inigoiri@apache.org>
Signed-off-by: Shilun Fan <slfan1989@apache.org>

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/Router.java

@@ -20,6 +20,7 @@ package org.apache.hadoop.yarn.server.router;
 
 import java.io.IOException;
 import java.net.InetAddress;
+import java.net.URL;
 import java.net.InetSocketAddress;
 import java.net.UnknownHostException;
 import java.util.concurrent.ScheduledThreadPoolExecutor;
@@ -38,6 +39,7 @@ import org.apache.hadoop.service.CompositeService;
 import org.apache.hadoop.util.JvmPauseMonitor;
 import org.apache.hadoop.util.ShutdownHookManager;
 import org.apache.hadoop.util.StringUtils;
+import org.apache.hadoop.util.VersionInfo;
 import org.apache.hadoop.yarn.YarnUncaughtExceptionHandler;
 import org.apache.hadoop.yarn.conf.YarnConfiguration;
 import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
@@ -55,6 +57,7 @@ import org.apache.hadoop.yarn.webapp.WebApps;
 import org.apache.hadoop.yarn.webapp.WebApps.Builder;
 import org.apache.hadoop.yarn.webapp.util.WebAppUtils;
 import org.apache.hadoop.yarn.webapp.util.WebServiceClient;
+import org.eclipse.jetty.webapp.WebAppContext;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -106,6 +109,8 @@ public class Router extends CompositeService {
 
   private static final String METRICS_NAME = "Router";
 
+  private static final String UI2_WEBAPP_NAME = "/ui2";
+
   private ScheduledThreadPoolExecutor scheduledExecutorService;
   private SubClusterCleaner subClusterCleaner;
 
@@ -226,7 +231,50 @@ public class Router extends CompositeService {
       String[] proxyParts = proxyHostAndPort.split(":");
       builder.withAttribute(WebAppProxy.PROXY_HOST_ATTRIBUTE, proxyParts[0]);
     }
-    webApp = builder.start(new RouterWebApp(this));
+    webApp = builder.start(new RouterWebApp(this), getUIWebAppContext());
+  }
+
+  private WebAppContext getUIWebAppContext() {
+    WebAppContext uiWebAppContext = null;
+    boolean isWebUI2Enabled = conf.getBoolean(YarnConfiguration.YARN_WEBAPP_UI2_ENABLE,
+        YarnConfiguration.DEFAULT_YARN_WEBAPP_UI2_ENABLE);
+
+    if(isWebUI2Enabled) {
+      String onDiskPath = conf.get(YarnConfiguration.YARN_WEBAPP_UI2_WARFILE_PATH);
+      uiWebAppContext = new WebAppContext();
+      uiWebAppContext.setContextPath(UI2_WEBAPP_NAME);
+
+      if (null == onDiskPath) {
+        String war = "hadoop-yarn-ui-" + VersionInfo.getVersion() + ".war";
+        URL url = getClass().getClassLoader().getResource(war);
+        if (null == url) {
+          onDiskPath = getWebAppsPath("ui2");
+        } else {
+          onDiskPath = url.getFile();
+        }
+      }
+
+      if (onDiskPath == null || onDiskPath.isEmpty()) {
+        LOG.error("No war file or webapps found for yarn federation!");
+      } else {
+        if (onDiskPath.endsWith(".war")) {
+          uiWebAppContext.setWar(onDiskPath);
+          LOG.info("Using war file at: {}.", onDiskPath);
+        } else {
+          uiWebAppContext.setResourceBase(onDiskPath);
+          LOG.info("Using webapps at: {}.", onDiskPath);
+        }
+      }
+    }
+    return uiWebAppContext;
+  }
+
+  private String getWebAppsPath(String appName) {
+    URL url = getClass().getClassLoader().getResource("webapps/" + appName);
+    if (url == null) {
+      return "";
+    }
+    return url.toString();
   }
 
   public static String getProxyHostAndPort(Configuration conf) {

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/test/java/org/apache/hadoop/yarn/server/router/TestRouter.java

@@ -143,7 +143,7 @@ public class TestRouter {
     WebAppContext webAppContext = httpServer2.getWebAppContext();
     ServletHandler servletHandler = webAppContext.getServletHandler();
     FilterHolder holder = servletHandler.getFilter("Cross Origin Filter");
-    CrossOriginFilter filter = CrossOriginFilter.class.cast(holder.getFilter());
+    CrossOriginFilter filter = (CrossOriginFilter) holder.getFilter();
 
     // 1. Simulate [example.com] for access
     HttpServletRequest mockReq = Mockito.mock(HttpServletRequest.class);