YARN-6992. Kill application button is visible even if the application is FINISHED in RM UI. Contributed by Suma Shivaprasad.

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

@@ -144,7 +144,8 @@ public class AppBlock extends HtmlBlock {
         && webUiType.equals(YarnWebParams.RM_WEB_UI)
         && conf.getBoolean(YarnConfiguration.RM_WEBAPP_UI_ACTIONS_ENABLED,
           YarnConfiguration.DEFAULT_RM_WEBAPP_UI_ACTIONS_ENABLED)
-            && !unsecuredUIForSecuredCluster) {
+            && !unsecuredUIForSecuredCluster
+            && !isAppInFinalState(app)) {
       // Application Kill
       html.div()
         .button()
@@ -419,4 +420,10 @@ public class AppBlock extends HtmlBlock {
     }
     return ret;
   }
+
+  private boolean isAppInFinalState(AppInfo app) {
+    return app.getAppState() == YarnApplicationState.FINISHED
+        || app.getAppState() == YarnApplicationState.FAILED
+        || app.getAppState() == YarnApplicationState.KILLED;
+  }
 }