YARN-6544. Add Null check RegistryDNS service while parsing registry records. Contributed by Karam Singh

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-registry/src/main/java/org/apache/hadoop/registry/server/dns/RegistryDNS.java

@@ -1393,19 +1393,28 @@ public class RegistryDNS extends AbstractService implements DNSOperations,
       throws IOException {
     ServiceRecordProcessor processor;
     try {
-      if (record.get(YarnRegistryAttributes.YARN_PERSISTENCE)
-          .equals(CONTAINER)) {
+      String yarnPersistanceValue = record.get(
+                                    YarnRegistryAttributes.YARN_PERSISTENCE);
+      if (yarnPersistanceValue != null) {
+        if (yarnPersistanceValue.equals(CONTAINER)) {
           // container registration.  the logic to identify and create the
-        // container entry needs to be enhanced/more accurate and associate to
-        // correct host
+          // container entry needs to be enhanced/more accurate and associate
+          // to correct host
           processor =
-            new ContainerServiceRecordProcessor(record, path, domainName, this);
+               new ContainerServiceRecordProcessor(record, path, domainName,
+                   this);
         } else {
+          LOG.debug("Creating ApplicationServiceRecordProcessor for {}",
+                    yarnPersistanceValue);
           processor =
                new ApplicationServiceRecordProcessor(record, path, domainName,
                    this);
         }
         processor.manageDNSRecords(command);
+      } else {
+        LOG.warn("Yarn Resgistry record {} does not contain {} attribute ",
+                  record.toString(), YarnRegistryAttributes.YARN_PERSISTENCE);
+      }
     } catch (Exception e) {
       throw new IOException(e);
     }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-registry/src/test/java/org/apache/hadoop/registry/server/dns/TestRegistryDNS.java

@@ -129,6 +129,16 @@ public class TestRegistryDNS extends Assert {
       + "  \"yarn:persistence\" : \"container\"\n"
       + "}\n";
 
+  private static final String CONTAINER_RECORD_YARN_PERSISTANCE_ABSENT = "{\n"
+      + "  \"type\" : \"JSONServiceRecord\",\n"
+      + "  \"description\" : \"YCLOUD\",\n"
+      + "  \"external\" : [ ],\n"
+      + "  \"internal\" : [ ],\n"
+      + "  \"yarn:id\" : \"container_e50_1451931954322_0016_01_000003\",\n"
+      + "  \"yarn:ip\" : \"172.17.0.19\",\n"
+      + "  \"yarn:hostname\" : \"0a134d6329bb\"\n"
+      + "}\n";
+
   @Before
   public void initialize() throws Exception {
     setRegistryDNS(new RegistryDNS("TestRegistry"));
@@ -219,6 +229,25 @@ public class TestRegistryDNS extends Assert {
     assertTrue("not an ARecord", recs[0] instanceof ARecord);
   }
 
+  @Test
+  public void testContainerRegistrationPersistanceAbsent() throws Exception {
+    ServiceRecord record = marshal.fromBytes("somepath",
+        CONTAINER_RECORD_YARN_PERSISTANCE_ABSENT.getBytes());
+    registryDNS.register(
+        "/registry/users/root/services/org-apache-slider/test1/components/"
+            + "container-e50-1451931954322-0016-01-000003",
+         record);
+
+    Name name =
+        Name.fromString("ctr-e50-1451931954322-0016-01-000002.hwx.test.");
+    Record question = Record.newRecord(name, Type.A, DClass.IN);
+    Message query = Message.newQuery(question);
+    byte[] responseBytes = registryDNS.generateReply(query, null);
+    Message response = new Message(responseBytes);
+    assertEquals("Excepting NXDOMAIN as Record must not have regsisterd wrong",
+        Rcode.NXDOMAIN, response.getRcode());
+  }
+
   @Test
   public void testRecordTTL() throws Exception {
     ServiceRecord record = getMarshal().fromBytes("somepath",