HADOOP-14309. Add PowerShell NodeFencer. Contributed by Inigo Goiri

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

@@ -69,7 +69,8 @@ public class NodeFencer {
   private static final Map<String, Class<? extends FenceMethod>> STANDARD_METHODS =
     ImmutableMap.<String, Class<? extends FenceMethod>>of(
         "shell", ShellCommandFencer.class,
-        "sshfence", SshFenceByTcpPort.class);
+        "sshfence", SshFenceByTcpPort.class,
+        "powershell", PowerShellFencer.class);
   
   private final List<FenceMethodWithArg> methods;
   

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

@@ -0,0 +1,154 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.ha;
+
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.net.InetSocketAddress;
+import java.nio.charset.StandardCharsets;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.conf.Configured;
+import org.apache.hadoop.util.StringUtils;
+
+/**
+ * Fencer method that uses PowerShell to remotely connect to a machine and kill
+ * the required process. This only works in Windows.
+ *
+ * The argument passed to this fencer should be a unique string in the
+ * "CommandLine" attribute for the "java.exe" process. For example, the full
+ * path for the Namenode: "org.apache.hadoop.hdfs.server.namenode.NameNode".
+ * The administrator can also shorten the name to "Namenode" if it's unique.
+ */
+public class PowerShellFencer extends Configured implements FenceMethod {
+
+  private static final Log LOG = LogFactory.getLog(PowerShellFencer.class);
+
+
+  @Override
+  public void checkArgs(String argStr) throws BadFencingConfigurationException {
+    LOG.info("The parameter for the PowerShell fencer is " + argStr);
+  }
+
+  @Override
+  public boolean tryFence(HAServiceTarget target, String argsStr)
+      throws BadFencingConfigurationException {
+
+    String processName = argsStr;
+    InetSocketAddress serviceAddr = target.getAddress();
+    String hostname = serviceAddr.getHostName();
+
+    // Use PowerShell to kill a remote process
+    String ps1script = buildPSScript(processName, hostname);
+    if (ps1script == null) {
+      LOG.error("Cannot build PowerShell script");
+      return false;
+    }
+
+    // Execute PowerShell script
+    LOG.info("Executing " + ps1script);
+    ProcessBuilder builder = new ProcessBuilder("powershell.exe", ps1script);
+    Process p = null;
+    try {
+      p = builder.start();
+      p.getOutputStream().close();
+    } catch (IOException e) {
+      LOG.warn("Unable to execute " + ps1script, e);
+      return false;
+    }
+
+    // Pump logs to stderr
+    StreamPumper errPumper = new StreamPumper(
+        LOG, "fencer", p.getErrorStream(), StreamPumper.StreamType.STDERR);
+    errPumper.start();
+
+    StreamPumper outPumper = new StreamPumper(
+        LOG, "fencer", p.getInputStream(), StreamPumper.StreamType.STDOUT);
+    outPumper.start();
+
+    // Waiting for the process to finish
+    int rc = 0;
+    try {
+      rc = p.waitFor();
+      errPumper.join();
+      outPumper.join();
+    } catch (InterruptedException ie) {
+      LOG.warn("Interrupted while waiting for fencing command: " + ps1script);
+      return false;
+    }
+
+    return rc == 0;
+  }
+
+  /**
+   * Build a PowerShell script to kill a java.exe process in a remote machine.
+   *
+   * @param processName Name of the process to kill. This is an attribute in
+   *                    CommandLine.
+   * @param host Host where the process is.
+   * @return Path of the PowerShell script.
+   */
+  private String buildPSScript(final String processName, final String host) {
+    LOG.info(
+        "Building PowerShell script to kill " + processName + " at " + host);
+    String ps1script = null;
+    BufferedWriter writer = null;
+    try {
+      File file = File.createTempFile("temp-fence-command", ".ps1");
+      file.deleteOnExit();
+      FileOutputStream fos = new FileOutputStream(file, false);
+      OutputStreamWriter osw =
+          new OutputStreamWriter(fos, StandardCharsets.UTF_8);
+      writer = new BufferedWriter(osw);
+
+      // Filter to identify the Namenode process
+      String filter = StringUtils.join(" and ", new String[] {
+          "Name LIKE '%java.exe%'",
+          "CommandLine LIKE '%" + processName+ "%'"});
+
+      // Identify the process
+      String cmd = "Get-WmiObject Win32_Process";
+      cmd += " -Filter \"" + filter + "\"";
+      // Remote location
+      cmd += " -Computer " + host;
+      // Kill it
+      cmd += " |% { $_.Terminate() }";
+
+      LOG.info("PowerShell command: " + cmd);
+      writer.write(cmd);
+      writer.flush();
+
+      ps1script = file.getAbsolutePath();
+    } catch (IOException ioe) {
+      LOG.error("Cannot create PowerShell script", ioe);
+    } finally {
+      if (writer != null) {
+        try {
+          writer.close();
+        } catch (IOException ioe) {
+          LOG.error("Cannot close PowerShell script", ioe);
+        }
+      }
+    }
+    return ps1script;
+  }
+}