Revert HDFS-7808.

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -793,9 +793,6 @@ Release 2.7.0 - UNRELEASED
     HDFS-6662. WebHDFS cannot open a file if its path contains "%".
     (Gerson Carlos via wheat9)
 
-    HDFS-7808. Remove obsolete -ns options in in DFSHAAdmin.java.
-    (Arshad Mohammad via wheat9)
-
     HDFS-7788. Post-2.6 namenode may not start up with an image containing
     inodes created with an old release. (Rushabh Shah via kihwal)
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSHAAdmin.java

@@ -18,6 +18,7 @@
 package org.apache.hadoop.hdfs.tools;
 
 import java.io.PrintStream;
+import java.util.Arrays;
 import java.util.Collection;
 
 import org.apache.commons.logging.Log;
@@ -97,6 +98,25 @@ public class DFSHAAdmin extends HAAdmin {
       printUsage(errOut);
       return -1;
     }
+
+    int i = 0;
+    String cmd = argv[i++];
+
+    if ("-ns".equals(cmd)) {
+      if (i == argv.length) {
+        errOut.println("Missing nameservice ID");
+        printUsage(errOut);
+        return -1;
+      }
+      nameserviceId = argv[i++];
+      if (i >= argv.length) {
+        errOut.println("Missing command");
+        printUsage(errOut);
+        return -1;
+      }
+      argv = Arrays.copyOfRange(argv, i, argv.length);
+    }
+
     return super.runCmd(argv);
   }
   

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSHAAdmin.java

@@ -146,6 +146,17 @@ public class TestDFSHAAdmin {
     }
   }
   
+  @Test
+  public void testNameserviceOption() throws Exception {
+    assertEquals(-1, runTool("-ns"));
+    assertOutputContains("Missing nameservice ID");
+    assertEquals(-1, runTool("-ns", "ns1"));
+    assertOutputContains("Missing command");
+    // "ns1" isn't defined but we check this lazily and help doesn't use the ns
+    assertEquals(0, runTool("-ns", "ns1", "-help", "transitionToActive"));
+    assertOutputContains("Transitions the service into Active");
+  }
+
   @Test
   public void testNamenodeResolution() throws Exception {
     Mockito.doReturn(STANDBY_READY_RESULT).when(mockProtocol).getServiceStatus();
@@ -267,6 +278,15 @@ public class TestDFSHAAdmin {
     assertEquals(0, runTool("-failover", "nn1", "nn2"));
   }
 
+  @Test
+  public void testFailoverWithFencerAndNameservice() throws Exception {
+    Mockito.doReturn(STANDBY_READY_RESULT).when(mockProtocol).getServiceStatus();
+    HdfsConfiguration conf = getHAConf();
+    conf.set(DFSConfigKeys.DFS_HA_FENCE_METHODS_KEY, getFencerTrueCommand());
+    tool.setConf(conf);
+    assertEquals(0, runTool("-ns", "ns1", "-failover", "nn1", "nn2"));
+  }
+
   @Test
   public void testFailoverWithFencerConfiguredAndForce() throws Exception {
     Mockito.doReturn(STANDBY_READY_RESULT).when(mockProtocol).getServiceStatus();

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSHAAdminMiniCluster.java

@@ -157,6 +157,9 @@ public class TestDFSHAAdminMiniCluster {
     assertEquals(0, runTool("-failover", "nn1", "nn2"));
     assertEquals(0, runTool("-failover", "nn2", "nn1"));
     
+    // Test failover with fencer and nameservice
+    assertEquals(0, runTool("-ns", "minidfs-ns", "-failover", "nn2", "nn1"));
+
     // Fencer has not run yet, since none of the above required fencing 
     assertEquals("", Files.toString(tmpFile, Charsets.UTF_8));