HDFS-8238. Move ClientProtocol to the hdfs-client. Contributed by Takanobu Asanuma.

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/HdfsClientConfigKeys.java

@@ -39,6 +39,7 @@ public interface HdfsClientConfigKeys {
   String  DFS_NAMENODE_HTTPS_ADDRESS_KEY = "dfs.namenode.https-address";
   String DFS_HA_NAMENODES_KEY_PREFIX = "dfs.ha.namenodes";
   int DFS_NAMENODE_RPC_PORT_DEFAULT = 8020;
+  String DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY = "dfs.namenode.kerberos.principal";
 
   /** dfs.client.retry configuration properties */
   interface Retry {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/ClientProtocol.java → hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ClientProtocol.java

@@ -43,7 +43,6 @@ import org.apache.hadoop.fs.permission.AclEntry;
 import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsAction;
 import org.apache.hadoop.fs.permission.FsPermission;
-import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.inotify.EventBatchList;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.RollingUpgradeAction;
 import org.apache.hadoop.hdfs.security.token.block.DataEncryptionKey;
@@ -61,17 +60,18 @@ import org.apache.hadoop.security.KerberosInfo;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.token.TokenInfo;
 
+import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY;
+
 /**********************************************************************
- * ClientProtocol is used by user code via 
- * {@link org.apache.hadoop.hdfs.DistributedFileSystem} class to communicate 
- * with the NameNode.  User code can manipulate the directory namespace, 
- * as well as open/close file streams, etc.
+ * ClientProtocol is used by user code via the DistributedFileSystem class to
+ * communicate with the NameNode.  User code can manipulate the directory
+ * namespace, as well as open/close file streams, etc.
  *
  **********************************************************************/
 @InterfaceAudience.Private
 @InterfaceStability.Evolving
 @KerberosInfo(
-    serverPrincipal = DFSConfigKeys.DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY)
+    serverPrincipal = DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY)
 @TokenInfo(DelegationTokenSelector.class)
 public interface ClientProtocol {
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java

@@ -490,7 +490,8 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final String  DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS = "dfs.short.circuit.shared.memory.watcher.interrupt.check.ms";
   public static final int     DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS_DEFAULT = 60000;
   public static final String  DFS_NAMENODE_KEYTAB_FILE_KEY = "dfs.namenode.keytab.file";
-  public static final String  DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY = "dfs.namenode.kerberos.principal";
+  public static final String  DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY =
+      HdfsClientConfigKeys.DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY;
   @Deprecated
   public static final String  DFS_NAMENODE_USER_NAME_KEY = DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY;
   public static final String  DFS_NAMENODE_KERBEROS_INTERNAL_SPNEGO_PRINCIPAL_KEY = "dfs.namenode.kerberos.internal.spnego.principal";