YARN-3541. Add version info on timeline service / generic history web UI and REST API. Contributed by Zhijie Shen

(cherry picked from commit 76afd28862c1f27011273659a82cd45903a77170)

hadoop-yarn-project/CHANGES.txt

@@ -66,6 +66,9 @@ Release 2.8.0 - UNRELEASED
     YARN-3505. Node's Log Aggregation Report with SUCCEED should not cached in 
     RMApps. (Xuan Gong via junping_du)
 
+    YARN-3541. Add version info on timeline service / generic history web UI
+    and REST API. (Zhijie Shen via xgong)
+
   IMPROVEMENTS
 
     YARN-644. Basic null check is not performed on passed in arguments before

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/api/records/timeline/TimelineAbout.java

@@ -0,0 +1,116 @@
+/**
+ * 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.api.records.timeline;
+
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlElement;
+import javax.xml.bind.annotation.XmlRootElement;
+
+@XmlRootElement(name = "about")
+@XmlAccessorType(XmlAccessType.NONE)
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+public class TimelineAbout {
+
+  private String about;
+  private String timelineServiceVersion;
+  private String timelineServiceBuildVersion;
+  private String timelineServiceVersionBuiltOn;
+  private String hadoopVersion;
+  private String hadoopBuildVersion;
+  private String hadoopVersionBuiltOn;
+
+  public TimelineAbout() {
+  }
+
+  public TimelineAbout(String about) {
+    this.about = about;
+  }
+
+  @XmlElement(name = "About")
+  public String getAbout() {
+    return about;
+  }
+
+  public void setAbout(String about) {
+    this.about = about;
+  }
+
+  @XmlElement(name = "timeline-service-version")
+  public String getTimelineServiceVersion() {
+    return timelineServiceVersion;
+  }
+
+  public void setTimelineServiceVersion(String timelineServiceVersion) {
+    this.timelineServiceVersion = timelineServiceVersion;
+  }
+
+  @XmlElement(name = "timeline-service-build-version")
+  public String getTimelineServiceBuildVersion() {
+    return timelineServiceBuildVersion;
+  }
+
+  public void setTimelineServiceBuildVersion(
+      String timelineServiceBuildVersion) {
+    this.timelineServiceBuildVersion = timelineServiceBuildVersion;
+  }
+
+  @XmlElement(name = "timeline-service-version-built-on")
+  public String getTimelineServiceVersionBuiltOn() {
+    return timelineServiceVersionBuiltOn;
+  }
+
+  public void setTimelineServiceVersionBuiltOn(
+      String timelineServiceVersionBuiltOn) {
+    this.timelineServiceVersionBuiltOn = timelineServiceVersionBuiltOn;
+  }
+
+  @XmlElement(name = "hadoop-version")
+  public String getHadoopVersion() {
+    return hadoopVersion;
+  }
+
+  public void setHadoopVersion(String hadoopVersion) {
+    this.hadoopVersion = hadoopVersion;
+  }
+
+  @XmlElement(name = "hadoop-build-version")
+  public String getHadoopBuildVersion() {
+    return hadoopBuildVersion;
+  }
+
+  public void setHadoopBuildVersion(String hadoopBuildVersion) {
+    this.hadoopBuildVersion = hadoopBuildVersion;
+  }
+
+  @XmlElement(name = "hadoop-version-built-on")
+  public String getHadoopVersionBuiltOn() {
+    return hadoopVersionBuiltOn;
+  }
+
+  public void setHadoopVersionBuiltOn(String hadoopVersionBuiltOn) {
+    this.hadoopVersionBuiltOn = hadoopVersionBuiltOn;
+  }
+}
+

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/timeline/TimelineUtils.java

@@ -26,7 +26,10 @@ import org.apache.hadoop.classification.InterfaceStability.Evolving;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.security.SecurityUtil;
+import org.apache.hadoop.util.VersionInfo;
+import org.apache.hadoop.yarn.api.records.timeline.TimelineAbout;
 import org.apache.hadoop.yarn.conf.YarnConfiguration;
+import org.apache.hadoop.yarn.util.YarnVersionInfo;
 import org.apache.hadoop.yarn.webapp.YarnJacksonJaxbJsonProvider;
 import org.codehaus.jackson.JsonGenerationException;
 import org.codehaus.jackson.map.JsonMappingException;
@@ -83,6 +86,17 @@ public class TimelineUtils {
     }
   }
 
+  public static TimelineAbout createTimelineAbout(String about) {
+    TimelineAbout tsInfo = new TimelineAbout(about);
+    tsInfo.setHadoopBuildVersion(VersionInfo.getBuildVersion());
+    tsInfo.setHadoopVersion(VersionInfo.getVersion());
+    tsInfo.setHadoopVersionBuiltOn(VersionInfo.getDate());
+    tsInfo.setTimelineServiceBuildVersion(YarnVersionInfo.getBuildVersion());
+    tsInfo.setTimelineServiceVersion(YarnVersionInfo.getVersion());
+    tsInfo.setTimelineServiceVersionBuiltOn(YarnVersionInfo.getDate());
+    return tsInfo;
+  }
+
   public static InetSocketAddress getTimelineTokenServiceAddress(
       Configuration conf) {
     InetSocketAddress timelineServiceAddr = null;

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/main/java/org/apache/hadoop/yarn/server/applicationhistoryservice/webapp/AHSController.java

@@ -34,6 +34,10 @@ public class AHSController extends Controller {
     setTitle("Application History");
   }
 
+  public void about() {
+    render(AboutPage.class);
+  }
+
   public void app() {
     render(AppPage.class);
   }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/main/java/org/apache/hadoop/yarn/server/applicationhistoryservice/webapp/AHSWebApp.java

@@ -56,6 +56,7 @@ public class AHSWebApp extends WebApp implements YarnWebParams {
     bind(ApplicationBaseProtocol.class).toInstance(historyClientService);
     bind(TimelineDataManager.class).toInstance(timelineDataManager);
     route("/", AHSController.class);
+    route("/about", AHSController.class, "about");
     route(pajoin("/apps", APP_STATE), AHSController.class);
     route(pajoin("/app", APPLICATION_ID), AHSController.class, "app");
     route(pajoin("/appattempt", APPLICATION_ATTEMPT_ID), AHSController.class,

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/main/java/org/apache/hadoop/yarn/server/applicationhistoryservice/webapp/AHSWebServices.java

@@ -34,6 +34,7 @@ import javax.ws.rs.core.MediaType;
 import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.api.records.YarnApplicationState;
 import org.apache.hadoop.yarn.api.ApplicationBaseProtocol;
+import org.apache.hadoop.yarn.api.records.timeline.TimelineAbout;
 import org.apache.hadoop.yarn.server.webapp.WebServices;
 import org.apache.hadoop.yarn.server.webapp.dao.AppAttemptInfo;
 import org.apache.hadoop.yarn.server.webapp.dao.AppAttemptsInfo;
@@ -41,6 +42,7 @@ import org.apache.hadoop.yarn.server.webapp.dao.AppInfo;
 import org.apache.hadoop.yarn.server.webapp.dao.AppsInfo;
 import org.apache.hadoop.yarn.server.webapp.dao.ContainerInfo;
 import org.apache.hadoop.yarn.server.webapp.dao.ContainersInfo;
+import org.apache.hadoop.yarn.util.timeline.TimelineUtils;
 import org.apache.hadoop.yarn.webapp.BadRequestException;
 
 import com.google.inject.Inject;
@@ -55,6 +57,16 @@ public class AHSWebServices extends WebServices {
     super(appBaseProt);
   }
 
+  @GET
+  @Path("/about")
+  @Produces({ MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML })
+  public TimelineAbout about(
+      @Context HttpServletRequest req,
+      @Context HttpServletResponse res) {
+    init(res);
+    return TimelineUtils.createTimelineAbout("Generic History Service API");
+  }
+
   @GET
   @Produces({ MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML })
   public AppsInfo get(@Context HttpServletRequest req,

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/main/java/org/apache/hadoop/yarn/server/applicationhistoryservice/webapp/AboutBlock.java

@@ -0,0 +1,47 @@
+/**
+ * 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.applicationhistoryservice.webapp;
+
+import com.google.inject.Inject;
+import org.apache.hadoop.util.VersionInfo;
+import org.apache.hadoop.yarn.api.records.timeline.TimelineAbout;
+import org.apache.hadoop.yarn.util.YarnVersionInfo;
+import org.apache.hadoop.yarn.util.timeline.TimelineUtils;
+import org.apache.hadoop.yarn.webapp.View;
+import org.apache.hadoop.yarn.webapp.view.HtmlBlock;
+import org.apache.hadoop.yarn.webapp.view.InfoBlock;
+
+public class AboutBlock extends HtmlBlock {
+  @Inject
+  AboutBlock(View.ViewContext ctx) {
+    super(ctx);
+  }
+
+  @Override
+  protected void render(Block html) {
+    TimelineAbout tsInfo = TimelineUtils.createTimelineAbout(
+        "Timeline Server - Generic History Service UI");
+    info("Timeline Server Overview").
+        _("Timeline Server Version:", tsInfo.getTimelineServiceBuildVersion() +
+            " on " + tsInfo.getTimelineServiceVersionBuiltOn()).
+        _("Hadoop Version:", tsInfo.getHadoopBuildVersion() +
+            " on " + tsInfo.getHadoopVersionBuiltOn());
+    html._(InfoBlock.class);
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/main/java/org/apache/hadoop/yarn/server/applicationhistoryservice/webapp/AboutPage.java

@@ -0,0 +1,36 @@
+/**
+ * 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.applicationhistoryservice.webapp;
+
+
+import org.apache.hadoop.yarn.webapp.SubView;
+import org.apache.hadoop.yarn.webapp.YarnWebParams;
+
+import static org.apache.hadoop.yarn.util.StringHelper.join;
+
+public class AboutPage extends AHSView {
+  @Override protected void preHead(Page.HTML<_> html) {
+    commonPreHead(html);
+    set(TITLE, "Timeline Server - Generic History Service");
+  }
+
+  @Override protected Class<? extends SubView> content() {
+    return AboutBlock.class;
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/main/java/org/apache/hadoop/yarn/server/applicationhistoryservice/webapp/NavBlock.java

@@ -43,6 +43,8 @@ public class NavBlock extends HtmlBlock {
         div("#nav").
             h3("Application History").
                 ul().
+                    li().a(url("about"), "About").
+                    _().
                     li().a(url("apps"), "Applications").
                         ul().
                             li().a(url("apps",

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/main/java/org/apache/hadoop/yarn/server/timeline/webapp/TimelineWebServices.java

@@ -42,17 +42,12 @@ import javax.ws.rs.WebApplicationException;
 import javax.ws.rs.core.Context;
 import javax.ws.rs.core.MediaType;
 import javax.ws.rs.core.Response;
-import javax.xml.bind.annotation.XmlAccessType;
-import javax.xml.bind.annotation.XmlAccessorType;
-import javax.xml.bind.annotation.XmlElement;
-import javax.xml.bind.annotation.XmlRootElement;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.apache.hadoop.classification.InterfaceAudience.Public;
-import org.apache.hadoop.classification.InterfaceStability.Unstable;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.util.StringUtils;
+import org.apache.hadoop.util.VersionInfo;
 import org.apache.hadoop.yarn.api.records.timeline.TimelineDomain;
 import org.apache.hadoop.yarn.api.records.timeline.TimelineDomains;
 import org.apache.hadoop.yarn.api.records.timeline.TimelineEntities;
@@ -65,6 +60,9 @@ import org.apache.hadoop.yarn.server.timeline.GenericObjectMapper;
 import org.apache.hadoop.yarn.server.timeline.NameValuePair;
 import org.apache.hadoop.yarn.server.timeline.TimelineDataManager;
 import org.apache.hadoop.yarn.server.timeline.TimelineReader.Field;
+import org.apache.hadoop.yarn.api.records.timeline.TimelineAbout;
+import org.apache.hadoop.yarn.util.YarnVersionInfo;
+import org.apache.hadoop.yarn.util.timeline.TimelineUtils;
 import org.apache.hadoop.yarn.webapp.BadRequestException;
 import org.apache.hadoop.yarn.webapp.ForbiddenException;
 import org.apache.hadoop.yarn.webapp.NotFoundException;
@@ -86,43 +84,16 @@ public class TimelineWebServices {
     this.timelineDataManager = timelineDataManager;
   }
 
-  @XmlRootElement(name = "about")
-  @XmlAccessorType(XmlAccessType.NONE)
-  @Public
-  @Unstable
-  public static class AboutInfo {
-
-    private String about;
-
-    public AboutInfo() {
-
-    }
-
-    public AboutInfo(String about) {
-      this.about = about;
-    }
-
-    @XmlElement(name = "About")
-    public String getAbout() {
-      return about;
-    }
-
-    public void setAbout(String about) {
-      this.about = about;
-    }
-
-  }
-
   /**
    * Return the description of the timeline web services.
    */
   @GET
   @Produces({ MediaType.APPLICATION_JSON /* , MediaType.APPLICATION_XML */})
-  public AboutInfo about(
+  public TimelineAbout about(
       @Context HttpServletRequest req,
       @Context HttpServletResponse res) {
     init(res);
-    return new AboutInfo("Timeline API");
+    return TimelineUtils.createTimelineAbout("Timeline API");
   }
 
   /**

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/test/java/org/apache/hadoop/yarn/server/applicationhistoryservice/webapp/TestAHSWebApp.java

@@ -87,6 +87,20 @@ public class TestAHSWebApp extends ApplicationHistoryStoreTestUtils {
     WebAppTests.flushOutput(injector);
   }
 
+  @Test
+  public void testAboutPage() throws Exception {
+    Injector injector =
+        WebAppTests.createMockInjector(ApplicationBaseProtocol.class,
+            mockApplicationHistoryClientService(0, 0, 0));
+    AboutPage aboutPageInstance = injector.getInstance(AboutPage.class);
+
+    aboutPageInstance.render();
+    WebAppTests.flushOutput(injector);
+
+    aboutPageInstance.render();
+    WebAppTests.flushOutput(injector);
+  }
+
   @Test
   public void testAppPage() throws Exception {
     Injector injector =

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/test/java/org/apache/hadoop/yarn/server/applicationhistoryservice/webapp/TestAHSWebServices.java

@@ -49,6 +49,8 @@ import org.apache.hadoop.yarn.server.security.ApplicationACLsManager;
 import org.apache.hadoop.yarn.server.timeline.TimelineDataManager;
 import org.apache.hadoop.yarn.server.timeline.TimelineStore;
 import org.apache.hadoop.yarn.server.timeline.security.TimelineACLsManager;
+import org.apache.hadoop.yarn.api.records.timeline.TimelineAbout;
+import org.apache.hadoop.yarn.util.timeline.TimelineUtils;
 import org.apache.hadoop.yarn.webapp.GenericExceptionHandler;
 import org.apache.hadoop.yarn.webapp.JerseyTestBase;
 import org.apache.hadoop.yarn.webapp.WebServicesTestUtils;
@@ -57,6 +59,7 @@ import org.codehaus.jettison.json.JSONArray;
 import org.codehaus.jettison.json.JSONException;
 import org.codehaus.jettison.json.JSONObject;
 import org.junit.AfterClass;
+import org.junit.Assert;
 import org.junit.BeforeClass;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -215,6 +218,34 @@ public class TestAHSWebServices extends JerseyTestBase {
     }
   }
 
+  @Test
+  public void testAbout() throws Exception {
+    WebResource r = resource();
+    ClientResponse response = r
+        .path("ws").path("v1").path("applicationhistory").path("about")
+        .queryParam("user.name", USERS[round])
+        .accept(MediaType.APPLICATION_JSON).get(ClientResponse.class);
+    assertEquals(MediaType.APPLICATION_JSON_TYPE, response.getType());
+    TimelineAbout actualAbout = response.getEntity(TimelineAbout.class);
+    TimelineAbout expectedAbout =
+        TimelineUtils.createTimelineAbout("Generic History Service API");
+    Assert.assertNotNull(
+        "Timeline service about response is null", actualAbout);
+    Assert.assertEquals(expectedAbout.getAbout(), actualAbout.getAbout());
+    Assert.assertEquals(expectedAbout.getTimelineServiceVersion(),
+        actualAbout.getTimelineServiceVersion());
+    Assert.assertEquals(expectedAbout.getTimelineServiceBuildVersion(),
+        actualAbout.getTimelineServiceBuildVersion());
+    Assert.assertEquals(expectedAbout.getTimelineServiceVersionBuiltOn(),
+        actualAbout.getTimelineServiceVersionBuiltOn());
+    Assert.assertEquals(expectedAbout.getHadoopVersion(),
+        actualAbout.getHadoopVersion());
+    Assert.assertEquals(expectedAbout.getHadoopBuildVersion(),
+        actualAbout.getHadoopBuildVersion());
+    Assert.assertEquals(expectedAbout.getHadoopVersionBuiltOn(),
+        actualAbout.getHadoopVersionBuiltOn());
+  }
+
   @Test
   public void testAppsQuery() throws Exception {
     WebResource r = resource();

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/test/java/org/apache/hadoop/yarn/server/timeline/webapp/TestTimelineWebServices.java

@@ -29,7 +29,6 @@ import java.util.Collections;
 import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
@@ -59,6 +58,8 @@ import org.apache.hadoop.yarn.server.timeline.TimelineDataManager;
 import org.apache.hadoop.yarn.server.timeline.TimelineStore;
 import org.apache.hadoop.yarn.server.timeline.security.TimelineACLsManager;
 import org.apache.hadoop.yarn.server.timeline.security.TimelineAuthenticationFilter;
+import org.apache.hadoop.yarn.api.records.timeline.TimelineAbout;
+import org.apache.hadoop.yarn.util.timeline.TimelineUtils;
 import org.apache.hadoop.yarn.webapp.GenericExceptionHandler;
 import org.apache.hadoop.yarn.webapp.JerseyTestBase;
 import org.apache.hadoop.yarn.webapp.YarnJacksonJaxbJsonProvider;
@@ -184,10 +185,24 @@ public class TestTimelineWebServices extends JerseyTestBase {
         .accept(MediaType.APPLICATION_JSON)
         .get(ClientResponse.class);
     assertEquals(MediaType.APPLICATION_JSON_TYPE, response.getType());
-    TimelineWebServices.AboutInfo about =
-        response.getEntity(TimelineWebServices.AboutInfo.class);
-    Assert.assertNotNull(about);
-    Assert.assertEquals("Timeline API", about.getAbout());
+    TimelineAbout actualAbout = response.getEntity(TimelineAbout.class);
+    TimelineAbout expectedAbout =
+        TimelineUtils.createTimelineAbout("Timeline API");
+    Assert.assertNotNull(
+        "Timeline service about response is null", actualAbout);
+    Assert.assertEquals(expectedAbout.getAbout(), actualAbout.getAbout());
+    Assert.assertEquals(expectedAbout.getTimelineServiceVersion(),
+        actualAbout.getTimelineServiceVersion());
+    Assert.assertEquals(expectedAbout.getTimelineServiceBuildVersion(),
+        actualAbout.getTimelineServiceBuildVersion());
+    Assert.assertEquals(expectedAbout.getTimelineServiceVersionBuiltOn(),
+        actualAbout.getTimelineServiceVersionBuiltOn());
+    Assert.assertEquals(expectedAbout.getHadoopVersion(),
+        actualAbout.getHadoopVersion());
+    Assert.assertEquals(expectedAbout.getHadoopBuildVersion(),
+        actualAbout.getHadoopBuildVersion());
+    Assert.assertEquals(expectedAbout.getHadoopVersionBuiltOn(),
+        actualAbout.getHadoopVersionBuiltOn());
   }
 
   private static void verifyEntities(TimelineEntities entities) {

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/TimelineServer.md

@@ -358,9 +358,17 @@ Here is a non-normative description of the API.
 
     GET /ws/v1/timeline/
 
-Returns a JSON object describing the server instance.
+Returns a JSON object describing the server instance and version information.
 
-     {"About":"Timeline API"}
+     {
+       About: "Timeline API",
+       timeline-service-version: "3.0.0-SNAPSHOT",
+       timeline-service-build-version: "3.0.0-SNAPSHOT from fcd0702c10ce574b887280476aba63d6682d5271 by zshen source checksum e9ec74ea3ff7bc9f3d35e9cac694fb",
+       timeline-service-version-built-on: "2015-05-13T19:45Z",
+       hadoop-version: "3.0.0-SNAPSHOT",
+       hadoop-build-version: "3.0.0-SNAPSHOT from fcd0702c10ce574b887280476aba63d6682d5271 by zshen source checksum 95874b192923b43cdb96a6e483afd60",
+       hadoop-version-built-on: "2015-05-13T19:44Z"
+     }
 
 
 ## <a name="REST_API_DOMAINS"></a>Domains `/ws/v1/timeline/domain`
@@ -889,6 +897,92 @@ Response Body:
 Users can access the generic historic information of applications via REST
 APIs.
 
+## <a name="REST_API_ABOUT"></a>About
+
+With the about API, you can get an timeline about resource that contains
+generic history REST API description and version information.
+
+It is essentially a XML/JSON-serialized form of the YARN `TimelineAbout`
+structure.
+
+### URI:
+
+Use the following URI to obtain an timeline about object.
+
+    http(s)://<timeline server http(s) address:port>/ws/v1/applicationhistory/about
+
+### HTTP Operations Supported:
+
+    GET
+
+### Query Parameters Supported:
+
+None
+
+### Elements of the `about` (Application) Object:
+
+| Item         | Data Type   | Description                   |
+|:---- |:----  |:---- |
+| `About` | string  | The description about the service |
+| `timeline-service-version` | string  | The timeline service version |
+| `timeline-service-build-version` | string  | The timeline service build version |
+| `timeline-service-version-built-on` | string  | On what time the timeline service is built |
+| `hadoop-version` | string  | Hadoop version |
+| `hadoop-build-version` | string  | Hadoop build version |
+| `hadoop-version-built-on` | string  | On what time Hadoop is built |
+
+### Response Examples:
+
+#### JSON response
+
+HTTP Request:
+
+    http://localhost:8188/ws/v1/applicationhistory/about
+
+Response Header:
+
+    HTTP/1.1 200 OK
+    Content-Type: application/json
+    Transfer-Encoding: chunked
+
+Response Body:
+
+    {
+      About: "Generic History Service API",
+      timeline-service-version: "3.0.0-SNAPSHOT",
+      timeline-service-build-version: "3.0.0-SNAPSHOT from fcd0702c10ce574b887280476aba63d6682d5271 by zshen source checksum e9ec74ea3ff7bc9f3d35e9cac694fb",
+      timeline-service-version-built-on: "2015-05-13T19:45Z",
+      hadoop-version: "3.0.0-SNAPSHOT",
+      hadoop-build-version: "3.0.0-SNAPSHOT from fcd0702c10ce574b887280476aba63d6682d5271 by zshen source checksum 95874b192923b43cdb96a6e483afd60",
+      hadoop-version-built-on: "2015-05-13T19:44Z"
+    }
+
+#### XML response
+
+HTTP Request:
+
+    GET http://localhost:8188/ws/v1/applicationhistory/about
+    Accept: application/xml
+
+Response Header:
+
+    HTTP/1.1 200 OK
+    Content-Type: application/xml
+    Content-Length: 748
+
+Response Body:
+
+     <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+     <about>
+       <About>Generic History Service API</About>
+       <hadoop-build-version>3.0.0-SNAPSHOT from fcd0702c10ce574b887280476aba63d6682d5271 by zshen source checksum 95874b192923b43cdb96a6e483afd60</hadoop-build-version>
+       <hadoop-version>3.0.0-SNAPSHOT</hadoop-version>
+       <hadoop-version-built-on>2015-05-13T19:44Z</hadoop-version-built-on>
+       <timeline-service-build-version>3.0.0-SNAPSHOT from fcd0702c10ce574b887280476aba63d6682d5271 by zshen source checksum e9ec74ea3ff7bc9f3d35e9cac694fb</timeline-service-build-version>
+       <timeline-service-version>3.0.0-SNAPSHOT</timeline-service-version>
+       <timeline-service-version-built-on>2015-05-13T19:45Z</timeline-service-version-built-on>
+     </about>
+
 ## <a name="REST_API_LIST_APPLICATIONS"></a>Application List
 
 With the Application List API, you can obtain a collection of resources, each
@@ -1129,7 +1223,8 @@ With the Application API, you can get an application resource contains
 information about a particular application that was running on an YARN
 cluster.
 
-It is essentially a JSON-serialized form of the YARN `ApplicationReport` structure.
+It is essentially a XML/JSON-serialized form of the YARN `ApplicationReport`
+structure.
 
 ### URI: