YARN-8236. Invalid kerberos principal file name cause NPE in native service. 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/client/ServiceClient.java

@@ -1077,28 +1077,32 @@ private void addKeytabResourceIfSecure(SliderFileSystem fileSystem,
       throw new YarnException(e);
     }
 
+    if (keytabURI.getScheme() != null) {
       switch (keytabURI.getScheme()) {
       case "hdfs":
         Path keytabOnhdfs = new Path(keytabURI);
         if (!fileSystem.getFileSystem().exists(keytabOnhdfs)) {
-        LOG.warn(service.getName() + "'s keytab (principalName = " +
+          LOG.warn(service.getName() + "'s keytab (principalName = "
-            principalName + ") doesn't exist at: " + keytabOnhdfs);
+              + principalName + ") doesn't exist at: " + keytabOnhdfs);
           return;
         }
-      LocalResource keytabRes =
+        LocalResource keytabRes = fileSystem.createAmResource(keytabOnhdfs,
-          fileSystem.createAmResource(keytabOnhdfs, LocalResourceType.FILE);
+            LocalResourceType.FILE);
         localResource.put(String.format(YarnServiceConstants.KEYTAB_LOCATION,
             service.getName()), keytabRes);
-      LOG.debug("Adding " + service.getName() + "'s keytab for " +
+        LOG.info("Adding " + service.getName() + "'s keytab for "
-          "localization, uri = " + keytabOnhdfs);
+            + "localization, uri = " + keytabOnhdfs);
         break;
       case "file":
-      LOG.debug("Using a keytab from localhost: " + keytabURI);
+        LOG.info("Using a keytab from localhost: " + keytabURI);
         break;
       default:
-      LOG.warn("Unsupported URI scheme " + keytabURI);
+        LOG.warn("Unsupported keytab URI scheme " + keytabURI);
         break;
       }
+    } else {
+      LOG.warn("Unsupported keytab URI scheme " + keytabURI);
+    }
   }
 
   public String updateLifetime(String serviceName, long lifetime)

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

@@ -103,4 +103,6 @@ public interface RestApiErrorMessages {
       + "expression element name %s specified in placement policy of component "
       + "%s. Expression element names should be a valid constraint name or an "
       + "expression name defined for this component only.";
+  String ERROR_KEYTAB_URI_SCHEME_INVALID = "Unsupported keytab URI scheme: %s";
+  String ERROR_KEYTAB_URI_INVALID = "Invalid keytab URI: %s";
 }

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

@@ -29,13 +29,14 @@
 import org.apache.hadoop.registry.client.binding.RegistryUtils;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.yarn.exceptions.YarnException;
-import org.apache.hadoop.yarn.service.api.records.Container;
-import org.apache.hadoop.yarn.service.api.records.Service;
 import org.apache.hadoop.yarn.service.api.records.Artifact;
 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.Container;
+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.Resource;
+import org.apache.hadoop.yarn.service.api.records.Service;
 import org.apache.hadoop.yarn.service.exceptions.SliderException;
 import org.apache.hadoop.yarn.service.conf.RestApiConstants;
 import org.apache.hadoop.yarn.service.exceptions.RestApiErrorMessages;
@@ -111,14 +112,7 @@ public static void validateAndResolveService(Service service,
     }
 
     if (UserGroupInformation.isSecurityEnabled()) {
-      if (!StringUtils.isEmpty(service.getKerberosPrincipal().getKeytab())) {
+      validateKerberosPrincipal(service.getKerberosPrincipal());
-        try {
-          // validate URI format
-          new URI(service.getKerberosPrincipal().getKeytab());
-        } catch (URISyntaxException e) {
-          throw new IllegalArgumentException(e);
-        }
-      }
     }
 
     // Validate the Docker client config.
@@ -145,9 +139,8 @@ public static void validateAndResolveService(Service service,
         throw new IllegalArgumentException("Component name collision: " +
             comp.getName());
       }
-      // If artifact is of type SERVICE (which cannot be filled from
+      // If artifact is of type SERVICE (which cannot be filled from global),
-      // global), read external service and add its components to this
+      // read external service and add its components to this service
-      // service
       if (comp.getArtifact() != null && comp.getArtifact().getType() ==
           Artifact.TypeEnum.SERVICE) {
         if (StringUtils.isEmpty(comp.getArtifact().getId())) {
@@ -226,6 +219,25 @@ public static void validateAndResolveService(Service service,
     }
   }
 
+  public static void validateKerberosPrincipal(
+      KerberosPrincipal kerberosPrincipal) throws IOException {
+    if (!StringUtils.isEmpty(kerberosPrincipal.getKeytab())) {
+      try {
+        // validate URI format
+        URI keytabURI = new URI(kerberosPrincipal.getKeytab());
+        if (keytabURI.getScheme() == null) {
+          throw new IllegalArgumentException(String.format(
+              RestApiErrorMessages.ERROR_KEYTAB_URI_SCHEME_INVALID,
+              kerberosPrincipal.getKeytab()));
+        }
+      } catch (URISyntaxException e) {
+        throw new IllegalArgumentException(
+            String.format(RestApiErrorMessages.ERROR_KEYTAB_URI_INVALID,
+                e.getLocalizedMessage()));
+      }
+    }
+  }
+
   private static void validateDockerClientConfiguration(Service service,
       org.apache.hadoop.conf.Configuration conf) throws IOException {
     String dockerClientConfig = service.getDockerClientConfig();

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

@@ -22,6 +22,7 @@
 import org.apache.hadoop.yarn.conf.YarnConfiguration;
 import org.apache.hadoop.yarn.service.api.records.Artifact;
 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.Resource;
@@ -45,6 +46,7 @@
 import static org.apache.hadoop.yarn.service.exceptions.RestApiErrorMessages.*;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
 
 /**
  * Test for ServiceApiUtil helper methods.
@@ -525,4 +527,43 @@ public void testPlacementPolicy() throws IOException {
       Assert.fail(NO_EXCEPTION_PREFIX + e.getMessage());
     }
   }
+
+  @Test
+  public void testKerberosPrincipal() throws IOException {
+    SliderFileSystem sfs = ServiceTestUtils.initMockFs();
+    Service app = createValidApplication("comp-a");
+    KerberosPrincipal kp = new KerberosPrincipal();
+    kp.setKeytab("/some/path");
+    kp.setPrincipalName("user/_HOST@domain.com");
+    app.setKerberosPrincipal(kp);
+
+    try {
+      ServiceApiUtil.validateKerberosPrincipal(app.getKerberosPrincipal());
+      Assert.fail(EXCEPTION_PREFIX + "service with invalid keytab URI scheme");
+    } catch (IllegalArgumentException e) {
+      assertEquals(
+          String.format(RestApiErrorMessages.ERROR_KEYTAB_URI_SCHEME_INVALID,
+              kp.getKeytab()),
+          e.getMessage());
+    }
+
+    kp.setKeytab("/ blank / in / paths");
+    try {
+      ServiceApiUtil.validateKerberosPrincipal(app.getKerberosPrincipal());
+      Assert.fail(EXCEPTION_PREFIX + "service with invalid keytab");
+    } catch (IllegalArgumentException e) {
+      // strip out the %s at the end of the RestApiErrorMessages string constant
+      assertTrue(e.getMessage().contains(
+          RestApiErrorMessages.ERROR_KEYTAB_URI_INVALID.substring(0,
+              RestApiErrorMessages.ERROR_KEYTAB_URI_INVALID.length() - 2)));
+    }
+
+    kp.setKeytab("file:///tmp/a.keytab");
+    // now it should succeed
+    try {
+      ServiceApiUtil.validateKerberosPrincipal(app.getKerberosPrincipal());
+    } catch (IllegalArgumentException e) {
+      Assert.fail(NO_EXCEPTION_PREFIX + e.getMessage());
+    }
+  }
 }