HADOOP-10903. Enhance hadoop classpath command to expand wildcards or write classpath into jar manifest. Contributed by Chris Nauroth.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1615386 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -479,6 +479,9 @@ Release 2.6.0 - UNRELEASED
 
     HADOOP-10900. CredentialShell args should use single-dash style. (wang)
 
+    HADOOP-10903. Enhance hadoop classpath command to expand wildcards or write
+    classpath into jar manifest. (cnauroth)
+
   OPTIMIZATIONS
 
   BUG FIXES

hadoop-common-project/hadoop-common/src/main/bin/hadoop

@@ -90,11 +90,6 @@ case $COMMAND in
     fi
     ;;
 
-  classpath)
-    echo $CLASSPATH
-    exit
-    ;;
-
   #core commands  
   *)
     # the core commands
@@ -118,6 +113,14 @@ case $COMMAND in
       CLASSPATH=${CLASSPATH}:${TOOL_PATH}
     elif [ "$COMMAND" = "credential" ] ; then
       CLASS=org.apache.hadoop.security.alias.CredentialShell
+    elif [ "$COMMAND" = "classpath" ] ; then
+      if [ "$#" -eq 1 ]; then
+        # No need to bother starting up a JVM for this simple case.
+        echo $CLASSPATH
+        exit
+      else
+        CLASS=org.apache.hadoop.util.Classpath
+      fi
     elif [[ "$COMMAND" = -*  ]] ; then
         # class and package names cannot begin with a -
         echo "Error: No command named \`$COMMAND' was found. Perhaps you meant \`hadoop ${COMMAND#-}'"

hadoop-common-project/hadoop-common/src/main/bin/hadoop.cmd

@@ -115,11 +115,14 @@ call :updatepath %HADOOP_BIN_PATH%
   )
 
   if %hadoop-command% == classpath (
+    if not defined hadoop-command-arguments (
+      @rem No need to bother starting up a JVM for this simple case.
       @echo %CLASSPATH%
-    goto :eof
+      exit /b
+    )
   )
   
-  set corecommands=fs version jar checknative distcp daemonlog archive
+  set corecommands=fs version jar checknative distcp daemonlog archive classpath
   for %%i in ( %corecommands% ) do (
     if %hadoop-command% == %%i set corecommand=true  
   )
@@ -175,6 +178,10 @@ call :updatepath %HADOOP_BIN_PATH%
   set CLASSPATH=%CLASSPATH%;%TOOL_PATH%
   goto :eof
 
+:classpath
+  set CLASS=org.apache.hadoop.util.Classpath
+  goto :eof
+
 :updatepath
   set path_to_add=%*
   set current_path_comparable=%path%

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Classpath.java

@@ -0,0 +1,125 @@
+/*
+ * 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.util;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.fs.FileUtil;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.shell.CommandFormat;
+import org.apache.hadoop.fs.shell.CommandFormat.UnknownOptionException;
+
+/**
+ * Command-line utility for getting the full classpath needed to launch a Hadoop
+ * client application.  If the hadoop script is called with "classpath" as the
+ * command, then it simply prints the classpath and exits immediately without
+ * launching a JVM.  The output likely will include wildcards in the classpath.
+ * If there are arguments passed to the classpath command, then this class gets
+ * called.  With the --glob argument, it prints the full classpath with wildcards
+ * expanded.  This is useful in situations where wildcard syntax isn't usable.
+ * With the --jar argument, it writes the classpath as a manifest in a jar file.
+ * This is useful in environments with short limitations on the maximum command
+ * line length, where it may not be possible to specify the full classpath in a
+ * command.  For example, the maximum command line length on Windows is 8191
+ * characters.
+ */
+@InterfaceAudience.Private
+public final class Classpath {
+  private static final String usage =
+    "classpath [--glob|--jar <path>|-h|--help] :\n"
+    + "  Prints the classpath needed to get the Hadoop jar and the required\n"
+    + "  libraries.\n"
+    + "  Options:\n"
+    + "\n"
+    + "  --glob       expand wildcards\n"
+    + "  --jar <path> write classpath as manifest in jar named <path>\n"
+    + "  -h, --help   print help\n";
+
+  /**
+   * Main entry point.
+   *
+   * @param args command-line arguments
+   */
+  public static void main(String[] args) {
+    if (args.length < 1 || args[0].equals("-h") || args[0].equals("--help")) {
+      System.out.println(usage);
+      return;
+    }
+
+    // Copy args, because CommandFormat mutates the list.
+    List<String> argsList = new ArrayList<String>(Arrays.asList(args));
+    CommandFormat cf = new CommandFormat(0, Integer.MAX_VALUE, "-glob", "-jar");
+    try {
+      cf.parse(argsList);
+    } catch (UnknownOptionException e) {
+      terminate(1, "unrecognized option");
+      return;
+    }
+
+    String classPath = System.getProperty("java.class.path");
+
+    if (cf.getOpt("-glob")) {
+      // The classpath returned from the property has been globbed already.
+      System.out.println(classPath);
+    } else if (cf.getOpt("-jar")) {
+      if (argsList.isEmpty() || argsList.get(0) == null ||
+          argsList.get(0).isEmpty()) {
+        terminate(1, "-jar option requires path of jar file to write");
+        return;
+      }
+
+      // Write the classpath into the manifest of a temporary jar file.
+      Path workingDir = new Path(System.getProperty("user.dir"));
+      final String tmpJarPath;
+      try {
+        tmpJarPath = FileUtil.createJarWithClassPath(classPath, workingDir,
+          System.getenv());
+      } catch (IOException e) {
+        terminate(1, "I/O error creating jar: " + e.getMessage());
+        return;
+      }
+
+      // Rename the temporary file to its final location.
+      String jarPath = argsList.get(0);
+      try {
+        FileUtil.replaceFile(new File(tmpJarPath), new File(jarPath));
+      } catch (IOException e) {
+        terminate(1, "I/O error renaming jar temporary file to path: " +
+          e.getMessage());
+        return;
+      }
+    }
+  }
+
+  /**
+   * Prints a message to stderr and exits with a status code.
+   *
+   * @param status exit code
+   * @param msg message
+   */
+  private static void terminate(int status, String msg) {
+    System.err.println(msg);
+    ExitUtil.terminate(status, msg);
+  }
+}

hadoop-common-project/hadoop-common/src/site/apt/CommandsManual.apt.vm

@@ -296,9 +296,24 @@ User Commands
 * <<<classpath>>>
 
    Prints the class path needed to get the Hadoop jar and the required
-   libraries.
+   libraries.  If called without arguments, then prints the classpath set up by
+   the command scripts, which is likely to contain wildcards in the classpath
+   entries.  Additional options print the classpath after wildcard expansion or
+   write the classpath into the manifest of a jar file.  The latter is useful in
+   environments where wildcards cannot be used and the expanded classpath exceeds
+   the maximum supported command line length.
 
-   Usage: <<<hadoop classpath>>>
+   Usage: <<<hadoop classpath [--glob|--jar <path>|-h|--help]>>>
+
+*-----------------+-----------------------------------------------------------+
+|| COMMAND_OPTION || Description
+*-----------------+-----------------------------------------------------------+
+| --glob          | expand wildcards
+*-----------------+-----------------------------------------------------------+
+| --jar <path>    | write classpath as manifest in jar named <path>
+*-----------------+-----------------------------------------------------------+
+| -h, --help      | print help
+*-----------------+-----------------------------------------------------------+
 
 Administration Commands
 

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestClasspath.java

@@ -0,0 +1,176 @@
+/**
+ * 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.util;
+
+import static org.junit.Assert.*;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.PrintStream;
+import java.nio.charset.Charset;
+import java.util.jar.Attributes;
+import java.util.jar.JarFile;
+import java.util.jar.Manifest;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.fs.FileUtil;
+import org.apache.hadoop.io.IOUtils;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * Tests covering the classpath command-line utility.
+ */
+public class TestClasspath {
+
+  private static final Log LOG = LogFactory.getLog(TestClasspath.class);
+  private static final File TEST_DIR = new File(
+    System.getProperty("test.build.data", "/tmp"), "TestClasspath");
+  private static final Charset UTF8 = Charset.forName("UTF-8");
+
+  static {
+    ExitUtil.disableSystemExit();
+  }
+
+  private PrintStream oldStdout, oldStderr;
+  private ByteArrayOutputStream stdout, stderr;
+  private PrintStream printStdout, printStderr;
+
+  @Before
+  public void setUp() {
+    assertTrue(FileUtil.fullyDelete(TEST_DIR));
+    assertTrue(TEST_DIR.mkdirs());
+    oldStdout = System.out;
+    oldStderr = System.err;
+
+    stdout = new ByteArrayOutputStream();
+    printStdout = new PrintStream(stdout);
+    System.setOut(printStdout);
+
+    stderr = new ByteArrayOutputStream();
+    printStderr = new PrintStream(stderr);
+    System.setErr(printStderr);
+  }
+
+  @After
+  public void tearDown() {
+    System.setOut(oldStdout);
+    System.setErr(oldStderr);
+    IOUtils.cleanup(LOG, printStdout, printStderr);
+    assertTrue(FileUtil.fullyDelete(TEST_DIR));
+  }
+
+  @Test
+  public void testGlob() {
+    Classpath.main(new String[] { "--glob" });
+    String strOut = new String(stdout.toByteArray(), UTF8);
+    assertEquals(System.getProperty("java.class.path"), strOut.trim());
+    assertTrue(stderr.toByteArray().length == 0);
+  }
+
+  @Test
+  public void testJar() throws IOException {
+    File file = new File(TEST_DIR, "classpath.jar");
+    Classpath.main(new String[] { "--jar", file.getAbsolutePath() });
+    assertTrue(stdout.toByteArray().length == 0);
+    assertTrue(stderr.toByteArray().length == 0);
+    assertTrue(file.exists());
+    assertJar(file);
+  }
+
+  @Test
+  public void testJarReplace() throws IOException {
+    // Run the command twice with the same output jar file, and expect success.
+    testJar();
+    testJar();
+  }
+
+  @Test
+  public void testJarFileMissing() throws IOException {
+    try {
+      Classpath.main(new String[] { "--jar" });
+      fail("expected exit");
+    } catch (ExitUtil.ExitException e) {
+      assertTrue(stdout.toByteArray().length == 0);
+      String strErr = new String(stderr.toByteArray(), UTF8);
+      assertTrue(strErr.contains("requires path of jar"));
+    }
+  }
+
+  @Test
+  public void testHelp() {
+    Classpath.main(new String[] { "--help" });
+    String strOut = new String(stdout.toByteArray(), UTF8);
+    assertTrue(strOut.contains("Prints the classpath"));
+    assertTrue(stderr.toByteArray().length == 0);
+  }
+
+  @Test
+  public void testHelpShort() {
+    Classpath.main(new String[] { "-h" });
+    String strOut = new String(stdout.toByteArray(), UTF8);
+    assertTrue(strOut.contains("Prints the classpath"));
+    assertTrue(stderr.toByteArray().length == 0);
+  }
+
+  @Test
+  public void testUnrecognized() {
+    try {
+      Classpath.main(new String[] { "--notarealoption" });
+      fail("expected exit");
+    } catch (ExitUtil.ExitException e) {
+      assertTrue(stdout.toByteArray().length == 0);
+      String strErr = new String(stderr.toByteArray(), UTF8);
+      assertTrue(strErr.contains("unrecognized option"));
+    }
+  }
+
+  /**
+   * Asserts that the specified file is a jar file with a manifest containing a
+   * non-empty classpath attribute.
+   *
+   * @param file File to check
+   * @throws IOException if there is an I/O error
+   */
+  private static void assertJar(File file) throws IOException {
+    JarFile jarFile = null;
+    try {
+      jarFile = new JarFile(file);
+      Manifest manifest = jarFile.getManifest();
+      assertNotNull(manifest);
+      Attributes mainAttributes = manifest.getMainAttributes();
+      assertNotNull(mainAttributes);
+      assertTrue(mainAttributes.containsKey(Attributes.Name.CLASS_PATH));
+      String classPathAttr = mainAttributes.getValue(Attributes.Name.CLASS_PATH);
+      assertNotNull(classPathAttr);
+      assertFalse(classPathAttr.isEmpty());
+    } finally {
+      // It's too bad JarFile doesn't implement Closeable.
+      if (jarFile != null) {
+        try {
+          jarFile.close();
+        } catch (IOException e) {
+          LOG.warn("exception closing jarFile: " + jarFile, e);
+        }
+      }
+    }
+  }
+}