YARN-11084. Introduce new config to specify AM default node-label when not specified. Contributed by Junfan Zhang.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java

@@ -4409,6 +4409,9 @@ public class YarnConfiguration extends Configuration {
   private static final String RM_NODE_LABELS_PREFIX = RM_PREFIX
       + "node-labels.";
 
+  public static final String AM_DEFAULT_NODE_LABEL =
+      RM_NODE_LABELS_PREFIX + "am.default-node-label-expression";
+
   public static final String RM_NODE_LABELS_PROVIDER_CONFIG =
       RM_NODE_LABELS_PREFIX + "provider";
 

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

@@ -83,6 +83,9 @@ import org.apache.hadoop.classification.VisibleForTesting;
 import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.SettableFuture;
 import org.apache.hadoop.yarn.util.StringHelper;
 
+import static org.apache.commons.lang.StringUtils.isEmpty;
+import static org.apache.commons.lang.StringUtils.isNotEmpty;
+
 /**
  * This class manages the list of applications for the resource manager.
  */
@@ -106,6 +109,7 @@ public class RMAppManager implements EventHandler<RMAppManagerEvent>,
   private boolean timelineServiceV2Enabled;
   private boolean nodeLabelsEnabled;
   private Set<String> exclusiveEnforcedPartitions;
+  private String amDefaultNodeLabel;
 
   private static final String USER_ID_PREFIX = "userid=";
 
@@ -134,6 +138,8 @@ public class RMAppManager implements EventHandler<RMAppManagerEvent>,
         .areNodeLabelsEnabled(rmContext.getYarnConfiguration());
     this.exclusiveEnforcedPartitions = YarnConfiguration
         .getExclusiveEnforcedPartitions(rmContext.getYarnConfiguration());
+    this.amDefaultNodeLabel = conf
+        .get(YarnConfiguration.AM_DEFAULT_NODE_LABEL, null);
   }
 
   /**
@@ -622,9 +628,12 @@ public class RMAppManager implements EventHandler<RMAppManagerEvent>,
         }
 
         // set label expression for AM ANY request if not set
-        if (null == anyReq.getNodeLabelExpression()) {
+        if (isEmpty(anyReq.getNodeLabelExpression())) {
-          anyReq.setNodeLabelExpression(submissionContext
+          if (isNotEmpty(amDefaultNodeLabel)) {
-              .getNodeLabelExpression());
+            anyReq.setNodeLabelExpression(amDefaultNodeLabel);
+          } else {
+            anyReq.setNodeLabelExpression(submissionContext.getNodeLabelExpression());
+          }
         }
 
         // Put ANY request at the front

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/TestAppManager.java

@@ -729,6 +729,33 @@ public class TestAppManager extends AppManagerTestBase{
         app.getAMResourceRequests());
   }
 
+  @Test
+  public void testRMAppSubmitAMContainerWithNoLabelByRMDefaultAMNodeLabel() throws Exception {
+    List<ResourceRequest> reqs = new ArrayList<>();
+    ResourceRequest anyReq = ResourceRequest.newInstance(
+        Priority.newInstance(1),
+        ResourceRequest.ANY, Resources.createResource(1024), 1, false, null,
+        ExecutionTypeRequest.newInstance(ExecutionType.GUARANTEED));
+    reqs.add(anyReq);
+    asContext.setAMContainerResourceRequests(cloneResourceRequests(reqs));
+    asContext.setNodeLabelExpression("fixed");
+
+    Configuration conf = new Configuration(false);
+    String defaultAMNodeLabel = "core";
+    conf.set(YarnConfiguration.AM_DEFAULT_NODE_LABEL, defaultAMNodeLabel);
+
+    when(mockDefaultQueueInfo.getAccessibleNodeLabels()).thenReturn(
+        new HashSet<String>() {{ add("core"); }});
+
+    TestRMAppManager newAppMonitor = createAppManager(rmContext, conf);
+    newAppMonitor.submitApplication(asContext, "test");
+
+    RMApp app = rmContext.getRMApps().get(appId);
+    waitUntilEventProcessed();
+    Assert.assertEquals(defaultAMNodeLabel,
+        app.getAMResourceRequests().get(0).getNodeLabelExpression());
+  }
+
   @Test
   public void testRMAppSubmitResource() throws Exception {
     asContext.setResource(Resources.createResource(1024));
@@ -836,6 +863,10 @@ public class TestAppManager extends AppManagerTestBase{
 
   private RMApp testRMAppSubmit() throws Exception {
     appMonitor.submitApplication(asContext, "test");
+    return waitUntilEventProcessed();
+  }
+
+  private RMApp waitUntilEventProcessed() throws InterruptedException {
     RMApp app = rmContext.getRMApps().get(appId);
     Assert.assertNotNull("app is null", app);
     Assert.assertEquals("app id doesn't match", appId, app.getApplicationId());

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

@@ -170,6 +170,14 @@ Applications can use following Java APIs to specify node label to request
 * `ResourceRequest.setNodeLabelExpression(..)` to set node label expression for individual resource requests. This can overwrite node label expression set in ApplicationSubmissionContext
 * Specify `setAMContainerResourceRequest.setNodeLabelExpression` in `ApplicationSubmissionContext` to indicate expected node label for application master container.
 
+__Default AM node-label Configuration__
+
+Property  | Value
+----- | ------
+yarn.resourcemanager.node-labels.am.default-node-label-expression | Overwrites default-node-label-expression only for the ApplicationMaster container. It is disabled by default.
+
+
+
 Monitoring
 ----------