YARN-11123. ResourceManager webapps test failures due to org.apache.hadoop.metrics2.MetricsException and subsequent java.net.BindException: Address already in use. Contributed by Szilard Nemeth

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/webapp/WebAppException.java

@@ -25,6 +25,11 @@
 public class WebAppException extends YarnRuntimeException {
 
   private static final long serialVersionUID = 1L;
+  private WebApp webApp;
+
+  public WebApp getWebApp() {
+    return webApp;
+  }
 
   public WebAppException(String msg) {
     super(msg);
@@ -35,6 +40,11 @@ public WebAppException(Throwable cause) {
   }
 
   public WebAppException(String msg, Throwable cause) {
+    this(msg, cause, null);
+  }
+
+  public WebAppException(String msg, Throwable cause, WebApp webApp) {
     super(msg, cause);
+    this.webApp = webApp;
   }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/webapp/WebApps.java

@@ -476,7 +476,7 @@ public WebApp start(WebApp webapp, WebAppContext ui2Context) {
         LOG.info("Web app " + name + " started at "
             + httpServer.getConnectorAddress(0).getPort());
       } catch (IOException e) {
-        throw new WebAppException("Error starting http server", e);
+        throw new WebAppException("Error starting http server", e, webApp);
       }
       return webApp;
     }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/ResourceManager.java

@@ -23,6 +23,7 @@
 import com.sun.jersey.spi.container.servlet.ServletContainer;
 
 import org.apache.hadoop.yarn.metrics.GenericEventTypeMetrics;
+import org.apache.hadoop.yarn.webapp.WebAppException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.slf4j.Marker;
@@ -1440,7 +1441,12 @@ protected void startWepApp() {
         IsResourceManagerActiveServlet.PATH_SPEC,
         IsResourceManagerActiveServlet.class);
 
+    try {
       webApp = builder.start(new RMWebApp(this), uiWebAppContext);
+    } catch (WebAppException e) {
+      webApp = e.getWebApp();
+      throw e;
+    }
   }
 
   private String getWebAppsPath(String appName) {