HADOOP-9524. Fix ShellCommandFencer to work on Windows. Contributed by Arpit Agarwal.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1476856 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -528,6 +528,9 @@ Trunk (Unreleased)
 
     HADOOP-9490. LocalFileSystem#reportChecksumFailure not closing the 
     checksum file handle before rename. (Ivan Mitic via suresh)
+
+    HADOOP-9524. Fix ShellCommandFencer to work on Windows.
+    (Arpit Agarwal via suresh)
     
 Release 2.0.5-beta - UNRELEASED
 

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ha/ShellCommandFencer.java

@@ -26,6 +26,7 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configured;
 
 import com.google.common.annotations.VisibleForTesting;
+import org.apache.hadoop.util.Shell;
 
 /**
  * Fencing method that runs a shell command. It should be specified
@@ -33,8 +34,8 @@ import com.google.common.annotations.VisibleForTesting;
  * <code>
  *   shell(/path/to/my/script.sh arg1 arg2 ...)
  * </code><br>
- * The string between '(' and ')' is passed directly to a bash shell and
- * may not include any closing parentheses.<p>
+ * The string between '(' and ')' is passed directly to a bash shell
+ * (cmd.exe on Windows) and may not include any closing parentheses.<p>
  * 
  * The shell command will be run with an environment set up to contain
  * all of the current Hadoop configuration variables, with the '_' character 
@@ -58,11 +59,11 @@ public class ShellCommandFencer
 
   /** Prefix for target parameters added to the environment */
   private static final String TARGET_PREFIX = "target_";
-  
+
   @VisibleForTesting
   static Log LOG = LogFactory.getLog(
       ShellCommandFencer.class);
-  
+
   @Override
   public void checkArgs(String args) throws BadFencingConfigurationException {
     if (args == null || args.isEmpty()) {
@@ -74,8 +75,14 @@ public class ShellCommandFencer
 
   @Override
   public boolean tryFence(HAServiceTarget target, String cmd) {
-    ProcessBuilder builder = new ProcessBuilder(
-        "bash", "-e", "-c", cmd);
+    ProcessBuilder builder;
+
+    if (!Shell.WINDOWS) {
+      builder = new ProcessBuilder("bash", "-e", "-c", cmd);
+    } else {
+      builder = new ProcessBuilder("cmd.exe", "/c", cmd);
+    }
+
     setConfAsEnvVars(builder.environment());
     addTargetInfoAsEnvVars(target, builder.environment());
 

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ha/TestNodeFencer.java

@@ -24,6 +24,7 @@ import java.util.List;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.conf.Configured;
+import org.apache.hadoop.util.Shell;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
@@ -33,7 +34,12 @@ import com.google.common.collect.Lists;
 public class TestNodeFencer {
 
   private HAServiceTarget MOCK_TARGET;
-  
+
+  // Fencer shell commands that always return true on Unix and Windows
+  // respectively. Lacking the POSIX 'true' command on Windows, we use
+  // the batch command 'rem'.
+  private static String FENCER_TRUE_COMMAND_UNIX = "shell(true)";
+  private static String FENCER_TRUE_COMMAND_WINDOWS = "shell(rem)";
 
   @Before
   public void clearMockState() {
@@ -48,6 +54,11 @@ public class TestNodeFencer {
         .when(MOCK_TARGET).getAddress();
   }
 
+  private static String getFencerTrueCommand() {
+    return Shell.WINDOWS ?
+        FENCER_TRUE_COMMAND_WINDOWS : FENCER_TRUE_COMMAND_UNIX;
+  }
+
   @Test
   public void testSingleFencer() throws BadFencingConfigurationException {
     NodeFencer fencer = setupFencer(
@@ -100,7 +111,7 @@ public class TestNodeFencer {
 
   @Test
   public void testShortNameShell() throws BadFencingConfigurationException {
-    NodeFencer fencer = setupFencer("shell(true)");
+    NodeFencer fencer = setupFencer(getFencerTrueCommand());
     assertTrue(fencer.fence(MOCK_TARGET));
   }