YARN-8350. NPE in service AM related to placement policy. Contributed by Gour Saha

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/component/Component.java

@@ -694,6 +694,7 @@ public class Component implements EventHandler<ComponentEvent> {
       // composite constraints then this AND-ed composite constraint is not
       // used.
       PlacementConstraint finalConstraint = null;
+      if (placementPolicy != null) {
         for (org.apache.hadoop.yarn.service.api.records.PlacementConstraint
             yarnServiceConstraint : placementPolicy.getConstraints()) {
           List<TargetExpression> targetExpressions = new ArrayList<>();
@@ -705,8 +706,9 @@ public class Component implements EventHandler<ComponentEvent> {
           // Add all node attributes
           for (Map.Entry<String, List<String>> attribute : yarnServiceConstraint
               .getNodeAttributes().entrySet()) {
-          targetExpressions.add(PlacementTargets.nodeAttribute(
+            targetExpressions
-              attribute.getKey(), attribute.getValue().toArray(new String[0])));
+                .add(PlacementTargets.nodeAttribute(attribute.getKey(),
+                    attribute.getValue().toArray(new String[0])));
           }
           // Add all node partitions
           if (!yarnServiceConstraint.getNodePartitions().isEmpty()) {
@@ -749,7 +751,9 @@ public class Component implements EventHandler<ComponentEvent> {
             finalConstraint = constraint;
           }
           LOG.debug("[COMPONENT {}] Placement constraint: {}",
-            componentSpec.getName(), constraint.getConstraintExpr().toString());
+              componentSpec.getName(),
+              constraint.getConstraintExpr().toString());
+        }
       }
       ResourceSizing resourceSizing = ResourceSizing.newInstance((int) count,
           resource);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/exceptions/RestApiErrorMessages.java

@@ -91,6 +91,14 @@ public interface RestApiErrorMessages {
 
   String ERROR_QUICKLINKS_FOR_COMP_INVALID = "Quicklinks specified at"
       + " component level, needs corresponding values set at service level";
+  // Note: %sin is not a typo. Constraint name is optional so the error messages
+  // below handle that scenario by adding a space if name is specified.
+  String ERROR_PLACEMENT_POLICY_CONSTRAINT_TYPE_NULL = "Type not specified "
+      + "for constraint %sin placement policy of component %s.";
+  String ERROR_PLACEMENT_POLICY_CONSTRAINT_SCOPE_NULL = "Scope not specified "
+      + "for constraint %sin placement policy of component %s.";
+  String ERROR_PLACEMENT_POLICY_CONSTRAINT_TAGS_NULL = "Tag(s) not specified "
+      + "for constraint %sin placement policy of component %s.";
   String ERROR_PLACEMENT_POLICY_TAG_NAME_NOT_SAME = "Invalid target tag %s "
       + "specified in placement policy of component %s. For now, target tags "
       + "support self reference only. Specifying anything other than its "

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/utils/ServiceApiUtil.java

@@ -40,6 +40,7 @@ import org.apache.hadoop.yarn.service.api.records.Component;
 import org.apache.hadoop.yarn.service.api.records.Configuration;
 import org.apache.hadoop.yarn.service.api.records.KerberosPrincipal;
 import org.apache.hadoop.yarn.service.api.records.PlacementConstraint;
+import org.apache.hadoop.yarn.service.api.records.PlacementPolicy;
 import org.apache.hadoop.yarn.service.api.records.Resource;
 import org.apache.hadoop.yarn.service.exceptions.SliderException;
 import org.apache.hadoop.yarn.service.conf.RestApiConstants;
@@ -314,9 +315,28 @@ public class ServiceApiUtil {
   private static void validatePlacementPolicy(List<Component> components,
       Set<String> componentNames) {
     for (Component comp : components) {
-      if (comp.getPlacementPolicy() != null) {
+      PlacementPolicy placementPolicy = comp.getPlacementPolicy();
-        for (PlacementConstraint constraint : comp.getPlacementPolicy()
+      if (placementPolicy != null) {
+        for (PlacementConstraint constraint : placementPolicy
             .getConstraints()) {
+          if (constraint.getType() == null) {
+            throw new IllegalArgumentException(String.format(
+              RestApiErrorMessages.ERROR_PLACEMENT_POLICY_CONSTRAINT_TYPE_NULL,
+              constraint.getName() == null ? "" : constraint.getName() + " ",
+              comp.getName()));
+          }
+          if (constraint.getScope() == null) {
+            throw new IllegalArgumentException(String.format(
+              RestApiErrorMessages.ERROR_PLACEMENT_POLICY_CONSTRAINT_SCOPE_NULL,
+              constraint.getName() == null ? "" : constraint.getName() + " ",
+              comp.getName()));
+          }
+          if (constraint.getTargetTags().isEmpty()) {
+            throw new IllegalArgumentException(String.format(
+              RestApiErrorMessages.ERROR_PLACEMENT_POLICY_CONSTRAINT_TAGS_NULL,
+              constraint.getName() == null ? "" : constraint.getName() + " ",
+              comp.getName()));
+          }
           for (String targetTag : constraint.getTargetTags()) {
             if (!comp.getName().equals(targetTag)) {
               throw new IllegalArgumentException(String.format(

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/test/java/org/apache/hadoop/yarn/service/TestServiceApiUtil.java

@@ -25,6 +25,8 @@ import org.apache.hadoop.yarn.service.api.records.Component;
 import org.apache.hadoop.yarn.service.api.records.KerberosPrincipal;
 import org.apache.hadoop.yarn.service.api.records.PlacementConstraint;
 import org.apache.hadoop.yarn.service.api.records.PlacementPolicy;
+import org.apache.hadoop.yarn.service.api.records.PlacementScope;
+import org.apache.hadoop.yarn.service.api.records.PlacementType;
 import org.apache.hadoop.yarn.service.api.records.Resource;
 import org.apache.hadoop.yarn.service.api.records.Service;
 import org.apache.hadoop.yarn.service.exceptions.RestApiErrorMessages;
@@ -503,13 +505,48 @@ public class TestServiceApiUtil {
     PlacementPolicy pp = new PlacementPolicy();
     PlacementConstraint pc = new PlacementConstraint();
     pc.setName("CA1");
-    pc.setTargetTags(Collections.singletonList("comp-invalid"));
     pp.setConstraints(Collections.singletonList(pc));
     comp.setPlacementPolicy(pp);
 
     try {
       ServiceApiUtil.validateAndResolveService(app, sfs, CONF_DNS_ENABLED);
-      Assert.fail(EXCEPTION_PREFIX + "service with empty placement");
+      Assert.fail(EXCEPTION_PREFIX + "constraint with no type");
+    } catch (IllegalArgumentException e) {
+      assertEquals(String.format(
+          RestApiErrorMessages.ERROR_PLACEMENT_POLICY_CONSTRAINT_TYPE_NULL,
+          "CA1 ", "comp-a"), e.getMessage());
+    }
+
+    // Set the type
+    pc.setType(PlacementType.ANTI_AFFINITY);
+
+    try {
+      ServiceApiUtil.validateAndResolveService(app, sfs, CONF_DNS_ENABLED);
+      Assert.fail(EXCEPTION_PREFIX + "constraint with no scope");
+    } catch (IllegalArgumentException e) {
+      assertEquals(String.format(
+          RestApiErrorMessages.ERROR_PLACEMENT_POLICY_CONSTRAINT_SCOPE_NULL,
+          "CA1 ", "comp-a"), e.getMessage());
+    }
+
+    // Set the scope
+    pc.setScope(PlacementScope.NODE);
+
+    try {
+      ServiceApiUtil.validateAndResolveService(app, sfs, CONF_DNS_ENABLED);
+      Assert.fail(EXCEPTION_PREFIX + "constraint with no tag(s)");
+    } catch (IllegalArgumentException e) {
+      assertEquals(String.format(
+          RestApiErrorMessages.ERROR_PLACEMENT_POLICY_CONSTRAINT_TAGS_NULL,
+          "CA1 ", "comp-a"), e.getMessage());
+    }
+
+    // Set a target tag - but an invalid one
+    pc.setTargetTags(Collections.singletonList("comp-invalid"));
+
+    try {
+      ServiceApiUtil.validateAndResolveService(app, sfs, CONF_DNS_ENABLED);
+      Assert.fail(EXCEPTION_PREFIX + "constraint with invalid tag name");
     } catch (IllegalArgumentException e) {
       assertEquals(
           String.format(
@@ -518,9 +555,10 @@ public class TestServiceApiUtil {
           e.getMessage());
     }
 
+    // Set valid target tags now
     pc.setTargetTags(Collections.singletonList("comp-a"));
 
-    // now it should succeed
+    // Finally it should succeed
     try {
       ServiceApiUtil.validateAndResolveService(app, sfs, CONF_DNS_ENABLED);
     } catch (IllegalArgumentException e) {