YARN-8934. [GPG] Add JvmMetricsInfo and pause monitor. Contributed by Bilwa S T.
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java
index aa990d3..9a8e48e 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java
@@ -3430,6 +3430,14 @@
public static final String FEDERATION_GPG_PREFIX =
FEDERATION_PREFIX + "gpg.";
+ public static final String GPG_WEBAPP_PREFIX = FEDERATION_GPG_PREFIX
+ + "webapp.";
+
+ /** Enable/disable CORS filter. */
+ public static final String GPG_WEBAPP_ENABLE_CORS_FILTER =
+ GPG_WEBAPP_PREFIX + "cross-origin.enabled";
+ public static final boolean DEFAULT_GPG_WEBAPP_ENABLE_CORS_FILTER = false;
+
// The number of threads to use for the GPG scheduled executor service
public static final String GPG_SCHEDULED_EXECUTOR_THREADS =
FEDERATION_GPG_PREFIX + "scheduled.executor.threads";
@@ -3457,6 +3465,22 @@
FEDERATION_GPG_PREFIX + "application.cleaner.interval-ms";
public static final long DEFAULT_GPG_APPCLEANER_INTERVAL_MS = -1;
+ /** The address of the GPG web application. */
+ public static final String GPG_WEBAPP_ADDRESS =
+ GPG_WEBAPP_PREFIX + "address";
+
+ public static final int DEFAULT_GPG_WEBAPP_PORT = 8069;
+ public static final String DEFAULT_GPG_WEBAPP_ADDRESS =
+ "0.0.0.0:" + DEFAULT_GPG_WEBAPP_PORT;
+
+ /** The https address of the GPG web application. */
+ public static final String GPG_WEBAPP_HTTPS_ADDRESS =
+ GPG_WEBAPP_PREFIX + "https.address";
+
+ public static final int DEFAULT_GPG_WEBAPP_HTTPS_PORT = 8070;
+ public static final String DEFAULT_GPG_WEBAPP_HTTPS_ADDRESS =
+ "0.0.0.0:" + DEFAULT_GPG_WEBAPP_HTTPS_PORT;
+
/**
* Specifications on how (many times) to contact Router for apps. We need to
* do this because Router might return partial application list because some
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/pom.xml b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/pom.xml
index 641a5f0..dc98113 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/pom.xml
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/pom.xml
@@ -237,6 +237,7 @@
<exclude>src/main/resources/webapps/test/.keep</exclude>
<exclude>src/main/resources/webapps/proxy/.keep</exclude>
<exclude>src/main/resources/webapps/node/.keep</exclude>
+ <exclude>src/main/resources/webapps/gpg/.keep</exclude>
<exclude>src/main/resources/webapps/static/dt-1.10.18/css/jquery.dataTables.css</exclude>
<exclude>src/main/resources/webapps/static/dt-1.10.18/css/custom_datatable.css</exclude>
<exclude>src/main/resources/webapps/static/dt-1.10.18/css/jui-dt.css</exclude>
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/webapp/util/WebAppUtils.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/webapp/util/WebAppUtils.java
index e62bf10..37b25ed 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/webapp/util/WebAppUtils.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/webapp/util/WebAppUtils.java
@@ -143,6 +143,16 @@
}
}
+ public static String getGPGWebAppURLWithoutScheme(Configuration conf) {
+ if (YarnConfiguration.useHttps(conf)) {
+ return conf.get(YarnConfiguration.GPG_WEBAPP_HTTPS_ADDRESS,
+ YarnConfiguration.DEFAULT_GPG_WEBAPP_HTTPS_ADDRESS);
+ } else {
+ return conf.get(YarnConfiguration.GPG_WEBAPP_ADDRESS,
+ YarnConfiguration.DEFAULT_GPG_WEBAPP_ADDRESS);
+ }
+ }
+
public static List<String> getProxyHostsAndPortsForAmFilter(
Configuration conf) {
List<String> addrs = new ArrayList<String>();
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml
index e496e28..7ec1d9a 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml
@@ -3706,6 +3706,34 @@
</property>
<property>
+ <description>Flag to enable cross-origin (CORS) support in the GPG. This flag
+ requires the CORS filter initializer to be added to the filter initializers
+ list in core-site.xml.</description>
+ <name>yarn.federation.gpg.webapp.cross-origin.enabled</name>
+ <value>false</value>
+ </property>
+
+ <property>
+ <description>
+ The http address of the GPG web application.
+ If only a host is provided as the value,
+ the webapp will be served on a random port.
+ </description>
+ <name>yarn.federation.gpg.webapp.address</name>
+ <value>0.0.0.0:8069</value>
+ </property>
+
+ <property>
+ <description>
+ The https address of the GPG web application.
+ If only a host is provided as the value,
+ the webapp will be served on a random port.
+ </description>
+ <name> yarn.federation.gpg.webapp.https.address</name>
+ <value>0.0.0.0:8070</value>
+ </property>
+
+ <property>
<description>
The configured policy generator class, runs NoOpGlobalPolicy by default
</description>
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/GlobalPolicyGenerator.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/GlobalPolicyGenerator.java
index 4444e4d..027e6e9 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/GlobalPolicyGenerator.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/GlobalPolicyGenerator.java
@@ -18,6 +18,8 @@
package org.apache.hadoop.yarn.server.globalpolicygenerator;
+import java.util.ArrayList;
+import java.util.List;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
@@ -25,9 +27,13 @@
import org.apache.commons.lang3.time.DurationFormatUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
+import org.apache.hadoop.metrics2.source.JvmMetrics;
import org.apache.hadoop.registry.client.api.RegistryOperations;
+import org.apache.hadoop.security.AuthenticationFilterInitializer;
+import org.apache.hadoop.security.HttpCrossOriginFilterInitializer;
import org.apache.hadoop.security.UserGroupInformation;
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.yarn.YarnUncaughtExceptionHandler;
@@ -37,9 +43,15 @@
import org.apache.hadoop.yarn.server.globalpolicygenerator.applicationcleaner.ApplicationCleaner;
import org.apache.hadoop.yarn.server.globalpolicygenerator.policygenerator.PolicyGenerator;
import org.apache.hadoop.yarn.server.globalpolicygenerator.subclustercleaner.SubClusterCleaner;
+import org.apache.hadoop.yarn.server.globalpolicygenerator.webapp.GPGWebApp;
+import org.apache.hadoop.yarn.webapp.WebApp;
+import org.apache.hadoop.yarn.webapp.WebApps;
+import org.apache.hadoop.yarn.webapp.util.WebAppUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
+import com.google.common.annotations.VisibleForTesting;
+
/**
* Global Policy Generator (GPG) is a Yarn Federation component. By tuning the
* Federation policies in Federation State Store, GPG overlooks the entire
@@ -60,6 +72,7 @@
public static final int SHUTDOWN_HOOK_PRIORITY = 30;
private AtomicBoolean isStopping = new AtomicBoolean(false);
private static final String METRICS_NAME = "Global Policy Generator";
+ private static long gpgStartupTime = System.currentTimeMillis();
// Federation Variables
private GPGContext gpgContext;
@@ -70,6 +83,9 @@
private SubClusterCleaner subClusterCleaner;
private ApplicationCleaner applicationCleaner;
private PolicyGenerator policyGenerator;
+ private String webAppAddress;
+ private JvmPauseMonitor pauseMonitor;
+ private WebApp webApp;
public GlobalPolicyGenerator() {
super(GlobalPolicyGenerator.class.getName());
@@ -110,7 +126,13 @@
this.policyGenerator = new PolicyGenerator(conf, this.gpgContext);
+ this.webAppAddress = WebAppUtils.getGPGWebAppURLWithoutScheme(conf);
+
DefaultMetricsSystem.initialize(METRICS_NAME);
+ JvmMetrics jm = JvmMetrics.initSingleton("GPG", null);
+ pauseMonitor = new JvmPauseMonitor();
+ addService(pauseMonitor);
+ jm.setPauseMonitor(pauseMonitor);
// super.serviceInit after all services are added
super.serviceInit(conf);
@@ -154,6 +176,7 @@
LOG.info("Scheduled policygenerator with interval: {}",
DurationFormatUtils.formatDurationISO(policyGeneratorIntervalMillis));
}
+ startWepApp();
}
@Override
@@ -176,6 +199,9 @@
if (this.isStopping.getAndSet(true)) {
return;
}
+ if (webApp != null) {
+ webApp.stop();
+ }
DefaultMetricsSystem.shutdown();
super.serviceStop();
}
@@ -202,6 +228,42 @@
this.start();
}
+ @VisibleForTesting
+ public void startWepApp() {
+ boolean enableCors = getConfig().getBoolean(
+ YarnConfiguration.GPG_WEBAPP_ENABLE_CORS_FILTER,
+ YarnConfiguration.DEFAULT_GPG_WEBAPP_ENABLE_CORS_FILTER);
+ if (enableCors) {
+ getConfig().setBoolean(HttpCrossOriginFilterInitializer.PREFIX
+ + HttpCrossOriginFilterInitializer.ENABLED_SUFFIX, true);
+ }
+
+ // Always load pseudo authentication filter to parse "user.name" in an URL
+ // to identify a HTTP request's user.
+ boolean hasHadoopAuthFilterInitializer = false;
+ String filterInitializerConfKey = "hadoop.http.filter.initializers";
+ Class<?>[] initializersClasses = getConfig()
+ .getClasses(filterInitializerConfKey);
+ List<String> targets = new ArrayList<String>();
+ if (initializersClasses != null) {
+ for (Class<?> initializer : initializersClasses) {
+ if (initializer.getName()
+ .equals(AuthenticationFilterInitializer.class.getName())) {
+ hasHadoopAuthFilterInitializer = true;
+ break;
+ }
+ targets.add(initializer.getName());
+ }
+ }
+ if (!hasHadoopAuthFilterInitializer) {
+ targets.add(AuthenticationFilterInitializer.class.getName());
+ getConfig().set(filterInitializerConfKey, StringUtils.join(",", targets));
+ }
+ LOG.info("Instantiating GPGWebApp at " + webAppAddress);
+ GPGWebApp gpgWebApp = new GPGWebApp(this);
+ webApp = WebApps.$for("gpg").at(webAppAddress).start(gpgWebApp);
+ }
+
@SuppressWarnings("resource")
public static void startGPG(String[] argv, Configuration conf) {
boolean federationEnabled =
@@ -225,6 +287,10 @@
}
}
+ public static long getGPGStartupTime() {
+ return gpgStartupTime;
+ }
+
public static void main(String[] argv) {
startGPG(argv, new YarnConfiguration());
}
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGController.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGController.java
new file mode 100644
index 0000000..c3955ea
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGController.java
@@ -0,0 +1,44 @@
+/**
+* Licensed to the Apache Software Foundation (ASF) under one
+* or more contributor license agreements. See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership. The ASF 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 org.apache.hadoop.yarn.server.globalpolicygenerator.webapp;
+
+import org.apache.hadoop.yarn.webapp.Controller;
+import com.google.inject.Inject;
+
+/**
+ * Controller for the GPG Web UI.
+ */
+public class GPGController extends Controller {
+
+ @Inject
+ GPGController(RequestContext ctx) {
+ super(ctx);
+ }
+
+ @Override
+ public void index() {
+ setTitle("GPG");
+ render(GPGOverviewPage.class);
+ }
+
+ public void overview() {
+ setTitle("GPG Details");
+ render(GPGOverviewPage.class);
+ }
+}
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGOverviewBlock.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGOverviewBlock.java
new file mode 100644
index 0000000..a2cb327
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGOverviewBlock.java
@@ -0,0 +1,50 @@
+/**
+* Licensed to the Apache Software Foundation (ASF) under one
+* or more contributor license agreements. See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership. The ASF 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 org.apache.hadoop.yarn.server.globalpolicygenerator.webapp;
+
+import java.util.Date;
+
+import org.apache.hadoop.util.VersionInfo;
+import org.apache.hadoop.yarn.server.globalpolicygenerator.GlobalPolicyGenerator;
+import org.apache.hadoop.yarn.util.YarnVersionInfo;
+import org.apache.hadoop.yarn.webapp.view.HtmlBlock;
+import org.apache.hadoop.yarn.webapp.view.InfoBlock;
+
+import com.google.inject.Inject;
+
+/**
+ * Overview block for the GPG Web UI.
+ */
+public class GPGOverviewBlock extends HtmlBlock {
+
+ @Inject
+ GPGOverviewBlock(GlobalPolicyGenerator gpg, ViewContext ctx) {
+ super(ctx);
+ }
+
+ @Override
+ protected void render(Block html) {
+ info("GPG Details")
+ .__("GPG started on",
+ new Date(GlobalPolicyGenerator.getGPGStartupTime()))
+ .__("GPG Version", YarnVersionInfo.getVersion())
+ .__("Hadoop Version", VersionInfo.getVersion());
+
+ html.__(InfoBlock.class);
+ }
+}
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGOverviewPage.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGOverviewPage.java
new file mode 100644
index 0000000..b7086ea
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGOverviewPage.java
@@ -0,0 +1,52 @@
+/**
+* Licensed to the Apache Software Foundation (ASF) under one
+* or more contributor license agreements. See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership. The ASF 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 org.apache.hadoop.yarn.server.globalpolicygenerator.webapp;
+
+import static org.apache.hadoop.yarn.webapp.view.JQueryUI.ACCORDION;
+import static org.apache.hadoop.yarn.webapp.view.JQueryUI.ACCORDION_ID;
+import static org.apache.hadoop.yarn.webapp.view.JQueryUI.initID;
+
+import org.apache.hadoop.yarn.webapp.SubView;
+import org.apache.hadoop.yarn.webapp.view.TwoColumnLayout;
+
+/**
+ * Overview page for the GPG Web UI.
+ */
+public class GPGOverviewPage extends TwoColumnLayout {
+
+ @Override
+ protected void preHead(Page.HTML<__> html) {
+ commonPreHead(html);
+ setTitle("GPG");
+ }
+
+ protected void commonPreHead(Page.HTML<__> html) {
+ set(ACCORDION_ID, "nav");
+ set(initID(ACCORDION, "nav"), "{autoHeight:false, active:0}");
+ }
+
+ @Override
+ protected Class<? extends SubView> nav() {
+ return NavBlock.class;
+ }
+
+ @Override
+ protected Class<? extends SubView> content() {
+ return GPGOverviewBlock.class;
+ }
+}
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGWebApp.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGWebApp.java
new file mode 100644
index 0000000..eedb179
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/GPGWebApp.java
@@ -0,0 +1,45 @@
+/**
+* Licensed to the Apache Software Foundation (ASF) under one
+* or more contributor license agreements. See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership. The ASF 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 org.apache.hadoop.yarn.server.globalpolicygenerator.webapp;
+
+import org.apache.hadoop.yarn.server.globalpolicygenerator.GlobalPolicyGenerator;
+import org.apache.hadoop.yarn.server.resourcemanager.webapp.JAXBContextResolver;
+import org.apache.hadoop.yarn.webapp.GenericExceptionHandler;
+import org.apache.hadoop.yarn.webapp.WebApp;
+
+/**
+ * The GPG webapp.
+ */
+public class GPGWebApp extends WebApp{
+ private GlobalPolicyGenerator gpg;
+
+ public GPGWebApp(GlobalPolicyGenerator gpg) {
+ this.gpg = gpg;
+ }
+
+ @Override
+ public void setup() {
+ bind(JAXBContextResolver.class);
+ bind(GPGWebApp.class).toInstance(this);
+ bind(GenericExceptionHandler.class);
+ if (gpg != null) {
+ bind(GlobalPolicyGenerator.class).toInstance(gpg);
+ }
+ route("/", GPGController.class, "overview");
+ }
+}
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/NavBlock.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/NavBlock.java
new file mode 100644
index 0000000..1fee9d08
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/NavBlock.java
@@ -0,0 +1,42 @@
+/**
+* Licensed to the Apache Software Foundation (ASF) under one
+* or more contributor license agreements. See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership. The ASF 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 org.apache.hadoop.yarn.server.globalpolicygenerator.webapp;
+
+import org.apache.hadoop.yarn.webapp.view.HtmlBlock;
+
+/**
+ * Navigation block for the GPG Web UI.
+ */
+public class NavBlock extends HtmlBlock {
+
+ @Override
+ public void render(Block html) {
+ html.
+ div("#nav").
+ h3("GPG").
+ ul().
+ li().a(url(""), "Overview").__().
+ __().
+ h3("Tools").
+ ul().
+ li().a("/conf", "Configuration").__().
+ li().a("/logs", "Local logs").__().
+ li().a("/stacks", "Server stacks").__().
+ li().a("/jmx?qry=Hadoop:*", "Server metrics").__().__().__();
+ }
+}
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/package-info.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/package-info.java
new file mode 100644
index 0000000..762212b
--- /dev/null
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/webapp/package-info.java
@@ -0,0 +1,24 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF 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.
+ */
+
+/**
+ * Classes comprising the policy generator for the GPG. Responsibilities include
+ * generating and updating policies based on the cluster status.
+ */
+
+package org.apache.hadoop.yarn.server.globalpolicygenerator.webapp;
\ No newline at end of file
