HADOOP-10776 Open up already widely-used APIs for delegation-token fetching & renewal to ecosystem projects. Contributed by Vinod Kumar Vavilapalli

Cherry picked from 24715cefe80fba531dd16a44ec1cead67c389eb1

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java

@@ -383,7 +383,8 @@ protected static FileSystem getFSofPath(final Path absOrFqPath,
    *         if the filesystem does not implement tokens
    * @see SecurityUtil#buildDTServiceName(URI, int)
    */
-  @InterfaceAudience.LimitedPrivate({ "HDFS", "MapReduce" })
+  @InterfaceAudience.Public
+  @InterfaceStability.Evolving
   public String getCanonicalServiceName() {
     return (getChildFileSystems() == null)
       ? SecurityUtil.buildDTServiceName(getUri(), getDefaultPort())
@@ -617,7 +618,8 @@ public Token<?> getDelegationToken(String renewer) throws IOException {
    * @return list of new delegation tokens
    * @throws IOException problems obtaining a token
    */
-  @InterfaceAudience.LimitedPrivate({ "HDFS", "MapReduce" })
+  @InterfaceAudience.Public
+  @InterfaceStability.Evolving
   public Token<?>[] addDelegationTokens(
       final String renewer, Credentials credentials) throws IOException {
     if (credentials == null) {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/AccessControlException.java

@@ -24,7 +24,7 @@
 /**
  * An exception class for access control related issues.
  */
-@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
+@InterfaceAudience.Public
 @InterfaceStability.Evolving
 public class AccessControlException extends IOException {
 

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/Credentials.java

@@ -57,7 +57,7 @@
  * A class that provides the facilities of reading and writing
  * secret keys and Tokens.
  */
-@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
+@InterfaceAudience.Public
 @InterfaceStability.Evolving
 public class Credentials implements Writable {
   private static final Log LOG = LogFactory.getLog(Credentials.class);

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/SecurityUtil.java

@@ -58,14 +58,20 @@
 
 import com.google.common.annotations.VisibleForTesting;
 
-@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
+/**
+ * Security Utils.
+ */
+@InterfaceAudience.Public
 @InterfaceStability.Evolving
-public class SecurityUtil {
+public final class SecurityUtil {
   public static final Log LOG = LogFactory.getLog(SecurityUtil.class);
   public static final String HOSTNAME_PATTERN = "_HOST";
   public static final String FAILED_TO_GET_UGI_MSG_HEADER = 
       "Failed to obtain user group information:";
 
+  private SecurityUtil() {
+  }
+
   // controls whether buildTokenService will use an ip or host/ip as given
   // by the user
   @VisibleForTesting

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java

@@ -87,7 +87,7 @@
  * user's username and groups. It supports both the Windows, Unix and Kerberos 
  * login modules.
  */
-@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce", "HBase", "Hive", "Oozie"})
+@InterfaceAudience.Public
 @InterfaceStability.Evolving
 public class UserGroupInformation {
   @VisibleForTesting
@@ -840,7 +840,7 @@ public static String trimLoginMethod(String userName) {
 
   /**
    * Log in a user using the given subject
-   * @parma subject the subject to use when logging in a user, or null to 
+   * @param subject the subject to use when logging in a user, or null to
    * create a new subject.
    * @throws IOException if login fails
    */
@@ -1694,7 +1694,7 @@ private synchronized Credentials getCredentialsInternal() {
   }
 
   /**
-   * Get the group names for this user. {@ #getGroups(String)} is less
+   * Get the group names for this user. {@link #getGroups()} is less
    * expensive alternative when checking for a contained element.
    * @return the list of users with the primary group first. If the command
    *    fails, it returns an empty list.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/authorize/AuthorizationException.java

@@ -29,7 +29,7 @@
  * 
  * This class <em>does not</em> provide the stack trace for security purposes.
  */
-@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce", "YARN"})
+@InterfaceAudience.Public
 @InterfaceStability.Evolving
 public class AuthorizationException extends AccessControlException {
   private static final long serialVersionUID = 1L;

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/token/Token.java

@@ -504,7 +504,7 @@ public void cancel(Configuration conf
    * A trivial renewer for token kinds that aren't managed. Sub-classes need
    * to implement getKind for their token kind.
    */
-  @InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
+  @InterfaceAudience.Public
   @InterfaceStability.Evolving
   public static class TrivialRenewer extends TokenRenewer {
 

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/token/delegation/AbstractDelegationTokenIdentifier.java

@@ -34,7 +34,7 @@
 
 import com.google.common.annotations.VisibleForTesting;
 
-@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
+@InterfaceAudience.Public
 @InterfaceStability.Evolving
 public abstract class AbstractDelegationTokenIdentifier 
 extends TokenIdentifier {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/token/delegation/AbstractDelegationTokenSecretManager.java

@@ -44,7 +44,7 @@
 
 import com.google.common.base.Preconditions;
 
-@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce", "Hive"})
+@InterfaceAudience.Public
 @InterfaceStability.Evolving
 public abstract 
 class AbstractDelegationTokenSecretManager<TokenIdent