HADOOP-10292. Restore HttpServer from branch-2.2 in branch-2. Merged from r1561967 in branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.3@1562617 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -363,6 +363,9 @@ Release 2.3.0 - UNRELEASED
     HADOOP-10255. Rename HttpServer to HttpServer2 to retain older 
     HttpServer in branch-2 for compatibility. (Haohui Mai via suresh)
 
+    HADOOP-10292. Restore HttpServer from branch-2.2 in branch-2.
+    (Haohui Mai via suresh)
+
 Release 2.2.0 - 2013-10-13
 
   INCOMPATIBLE CHANGES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/http/HttpServer.java

@@ -0,0 +1,1103 @@
+/**
+ * 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.http;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.net.BindException;
+import java.net.InetSocketAddress;
+import java.net.URL;
+import java.security.GeneralSecurityException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import javax.net.ssl.SSLServerSocketFactory;
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletContext;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletRequestWrapper;
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.conf.ConfServlet;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.CommonConfigurationKeys;
+import org.apache.hadoop.jmx.JMXJsonServlet;
+import org.apache.hadoop.log.LogLevel;
+import org.apache.hadoop.metrics.MetricsServlet;
+import org.apache.hadoop.security.SecurityUtil;
+import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.security.authentication.server.AuthenticationFilter;
+import org.apache.hadoop.security.authorize.AccessControlList;
+import org.apache.hadoop.security.ssl.SSLFactory;
+import org.apache.hadoop.util.ReflectionUtils;
+import org.apache.hadoop.util.Shell;
+import org.mortbay.io.Buffer;
+import org.mortbay.jetty.Connector;
+import org.mortbay.jetty.Handler;
+import org.mortbay.jetty.MimeTypes;
+import org.mortbay.jetty.Server;
+import org.mortbay.jetty.handler.ContextHandler;
+import org.mortbay.jetty.handler.ContextHandlerCollection;
+import org.mortbay.jetty.nio.SelectChannelConnector;
+import org.mortbay.jetty.security.SslSocketConnector;
+import org.mortbay.jetty.servlet.Context;
+import org.mortbay.jetty.servlet.DefaultServlet;
+import org.mortbay.jetty.servlet.FilterHolder;
+import org.mortbay.jetty.servlet.FilterMapping;
+import org.mortbay.jetty.servlet.ServletHandler;
+import org.mortbay.jetty.servlet.ServletHolder;
+import org.mortbay.jetty.webapp.WebAppContext;
+import org.mortbay.thread.QueuedThreadPool;
+import org.mortbay.util.MultiException;
+
+import com.sun.jersey.spi.container.servlet.ServletContainer;
+
+/**
+ * Create a Jetty embedded server to answer http requests. The primary goal
+ * is to serve up status information for the server.
+ * There are three contexts:
+ *   "/logs/" -> points to the log directory
+ *   "/static/" -> points to common static files (src/webapps/static)
+ *   "/" -> the jsp server code from (src/webapps/<name>)
+ *
+ * This class comes from the HttpServer in branch-2.2. HDFS and YARN have
+ * moved to use HttpServer2. This class exists for compatibility reasons, it
+ * stays in hadoop-common to allow HBase working with both Hadoop 2.2
+ * and Hadoop 2.3. See HBASE-10336 for more details.
+ */
+@InterfaceAudience.LimitedPrivate({"HBase"})
+@InterfaceStability.Evolving
+@Deprecated
+public class HttpServer implements FilterContainer {
+  public static final Log LOG = LogFactory.getLog(HttpServer.class);
+
+  static final String FILTER_INITIALIZER_PROPERTY
+      = "hadoop.http.filter.initializers";
+  static final String HTTP_MAX_THREADS = "hadoop.http.max.threads";
+
+  // The ServletContext attribute where the daemon Configuration
+  // gets stored.
+  public static final String CONF_CONTEXT_ATTRIBUTE = "hadoop.conf";
+  public static final String ADMINS_ACL = "admins.acl";
+  public static final String SPNEGO_FILTER = "SpnegoFilter";
+  public static final String NO_CACHE_FILTER = "NoCacheFilter";
+
+  public static final String BIND_ADDRESS = "bind.address";
+
+  private AccessControlList adminsAcl;
+
+  private SSLFactory sslFactory;
+  protected final Server webServer;
+  protected final Connector listener;
+  protected final WebAppContext webAppContext;
+  protected final boolean findPort;
+  protected final Map<Context, Boolean> defaultContexts =
+      new HashMap<Context, Boolean>();
+  protected final List<String> filterNames = new ArrayList<String>();
+  private static final int MAX_RETRIES = 10;
+  static final String STATE_DESCRIPTION_ALIVE = " - alive";
+  static final String STATE_DESCRIPTION_NOT_LIVE = " - not live";
+
+  private final boolean listenerStartedExternally;
+  
+  /** Same as this(name, bindAddress, port, findPort, null); */
+  public HttpServer(String name, String bindAddress, int port, boolean findPort
+      ) throws IOException {
+    this(name, bindAddress, port, findPort, new Configuration());
+  }
+
+  public HttpServer(String name, String bindAddress, int port,
+      boolean findPort, Configuration conf, Connector connector) throws IOException {
+    this(name, bindAddress, port, findPort, conf, null, connector, null);
+  }
+
+  /**
+   * Create a status server on the given port. Allows you to specify the
+   * path specifications that this server will be serving so that they will be
+   * added to the filters properly.  
+   * 
+   * @param name The name of the server
+   * @param bindAddress The address for this server
+   * @param port The port to use on the server
+   * @param findPort whether the server should start at the given port and 
+   *        increment by 1 until it finds a free port.
+   * @param conf Configuration 
+   * @param pathSpecs Path specifications that this httpserver will be serving. 
+   *        These will be added to any filters.
+   */
+  public HttpServer(String name, String bindAddress, int port,
+      boolean findPort, Configuration conf, String[] pathSpecs) throws IOException {
+    this(name, bindAddress, port, findPort, conf, null, null, pathSpecs);
+  }
+  
+  /**
+   * Create a status server on the given port.
+   * The jsp scripts are taken from src/webapps/<name>.
+   * @param name The name of the server
+   * @param port The port to use on the server
+   * @param findPort whether the server should start at the given port and 
+   *        increment by 1 until it finds a free port.
+   * @param conf Configuration 
+   */
+  public HttpServer(String name, String bindAddress, int port,
+      boolean findPort, Configuration conf) throws IOException {
+    this(name, bindAddress, port, findPort, conf, null, null, null);
+  }
+
+  public HttpServer(String name, String bindAddress, int port,
+      boolean findPort, Configuration conf, AccessControlList adminsAcl) 
+      throws IOException {
+    this(name, bindAddress, port, findPort, conf, adminsAcl, null, null);
+  }
+
+  /**
+   * Create a status server on the given port.
+   * The jsp scripts are taken from src/webapps/<name>.
+   * @param name The name of the server
+   * @param bindAddress The address for this server
+   * @param port The port to use on the server
+   * @param findPort whether the server should start at the given port and 
+   *        increment by 1 until it finds a free port.
+   * @param conf Configuration 
+   * @param adminsAcl {@link AccessControlList} of the admins
+   */
+  public HttpServer(String name, String bindAddress, int port,
+      boolean findPort, Configuration conf, AccessControlList adminsAcl, 
+      Connector connector) throws IOException {
+    this(name, bindAddress, port, findPort, conf, adminsAcl, connector, null);
+  }
+
+  /**
+   * Create a status server on the given port.
+   * The jsp scripts are taken from src/webapps/<name>.
+   * @param name The name of the server
+   * @param bindAddress The address for this server
+   * @param port The port to use on the server
+   * @param findPort whether the server should start at the given port and 
+   *        increment by 1 until it finds a free port.
+   * @param conf Configuration 
+   * @param adminsAcl {@link AccessControlList} of the admins
+   * @param connector A jetty connection listener
+   * @param pathSpecs Path specifications that this httpserver will be serving. 
+   *        These will be added to any filters.
+   */
+  public HttpServer(String name, String bindAddress, int port,
+      boolean findPort, Configuration conf, AccessControlList adminsAcl, 
+      Connector connector, String[] pathSpecs) throws IOException {
+    webServer = new Server();
+    this.findPort = findPort;
+    this.adminsAcl = adminsAcl;
+    
+    if(connector == null) {
+      listenerStartedExternally = false;
+      if (HttpConfig.isSecure()) {
+        sslFactory = new SSLFactory(SSLFactory.Mode.SERVER, conf);
+        try {
+          sslFactory.init();
+        } catch (GeneralSecurityException ex) {
+          throw new IOException(ex);
+        }
+        SslSocketConnector sslListener = new SslSocketConnector() {
+          @Override
+          protected SSLServerSocketFactory createFactory() throws Exception {
+            return sslFactory.createSSLServerSocketFactory();
+          }
+        };
+        listener = sslListener;
+      } else {
+        listener = createBaseListener(conf);
+      }
+      listener.setHost(bindAddress);
+      listener.setPort(port);
+    } else {
+      listenerStartedExternally = true;
+      listener = connector;
+    }
+    
+    webServer.addConnector(listener);
+
+    int maxThreads = conf.getInt(HTTP_MAX_THREADS, -1);
+    // If HTTP_MAX_THREADS is not configured, QueueThreadPool() will use the
+    // default value (currently 250).
+    QueuedThreadPool threadPool = maxThreads == -1 ?
+        new QueuedThreadPool() : new QueuedThreadPool(maxThreads);
+    threadPool.setDaemon(true);
+    webServer.setThreadPool(threadPool);
+
+    final String appDir = getWebAppsPath(name);
+    ContextHandlerCollection contexts = new ContextHandlerCollection();
+    webServer.setHandler(contexts);
+
+    webAppContext = new WebAppContext();
+    webAppContext.setDisplayName(name);
+    webAppContext.setContextPath("/");
+    webAppContext.setWar(appDir + "/" + name);
+    webAppContext.getServletContext().setAttribute(CONF_CONTEXT_ATTRIBUTE, conf);
+    webAppContext.getServletContext().setAttribute(ADMINS_ACL, adminsAcl);
+    addNoCacheFilter(webAppContext);
+    webServer.addHandler(webAppContext);
+
+    addDefaultApps(contexts, appDir, conf);
+        
+    addGlobalFilter("safety", QuotingInputFilter.class.getName(), null);
+    final FilterInitializer[] initializers = getFilterInitializers(conf); 
+    if (initializers != null) {
+      conf = new Configuration(conf);
+      conf.set(BIND_ADDRESS, bindAddress);
+      for(FilterInitializer c : initializers) {
+        c.initFilter(this, conf);
+      }
+    }
+
+    addDefaultServlets();
+
+    if (pathSpecs != null) {
+      for (String path : pathSpecs) {
+        LOG.info("adding path spec: " + path);
+        addFilterPathMapping(path, webAppContext);
+      }
+    }
+  }
+
+  @SuppressWarnings("unchecked")
+  private void addNoCacheFilter(WebAppContext ctxt) {
+    defineFilter(ctxt, NO_CACHE_FILTER,
+      NoCacheFilter.class.getName(), Collections.EMPTY_MAP, new String[] { "/*"});
+  }
+
+  /**
+   * Create a required listener for the Jetty instance listening on the port
+   * provided. This wrapper and all subclasses must create at least one
+   * listener.
+   */
+  public Connector createBaseListener(Configuration conf) throws IOException {
+    return HttpServer.createDefaultChannelConnector();
+  }
+  
+  @InterfaceAudience.Private
+  public static Connector createDefaultChannelConnector() {
+    SelectChannelConnector ret = new SelectChannelConnector();
+    ret.setLowResourceMaxIdleTime(10000);
+    ret.setAcceptQueueSize(128);
+    ret.setResolveNames(false);
+    ret.setUseDirectBuffers(false);
+    if(Shell.WINDOWS) {
+      // result of setting the SO_REUSEADDR flag is different on Windows
+      // http://msdn.microsoft.com/en-us/library/ms740621(v=vs.85).aspx
+      // without this 2 NN's can start on the same machine and listen on 
+      // the same port with indeterminate routing of incoming requests to them
+      ret.setReuseAddress(false);
+    }
+    ret.setHeaderBufferSize(1024*64);
+    return ret;
+  }
+
+  /** Get an array of FilterConfiguration specified in the conf */
+  private static FilterInitializer[] getFilterInitializers(Configuration conf) {
+    if (conf == null) {
+      return null;
+    }
+
+    Class<?>[] classes = conf.getClasses(FILTER_INITIALIZER_PROPERTY);
+    if (classes == null) {
+      return null;
+    }
+
+    FilterInitializer[] initializers = new FilterInitializer[classes.length];
+    for(int i = 0; i < classes.length; i++) {
+      initializers[i] = (FilterInitializer)ReflectionUtils.newInstance(
+          classes[i], conf);
+    }
+    return initializers;
+  }
+
+  /**
+   * Add default apps.
+   * @param appDir The application directory
+   * @throws IOException
+   */
+  protected void addDefaultApps(ContextHandlerCollection parent,
+      final String appDir, Configuration conf) throws IOException {
+    // set up the context for "/logs/" if "hadoop.log.dir" property is defined. 
+    String logDir = System.getProperty("hadoop.log.dir");
+    if (logDir != null) {
+      Context logContext = new Context(parent, "/logs");
+      logContext.setResourceBase(logDir);
+      logContext.addServlet(AdminAuthorizedServlet.class, "/*");
+      if (conf.getBoolean(
+          CommonConfigurationKeys.HADOOP_JETTY_LOGS_SERVE_ALIASES,
+          CommonConfigurationKeys.DEFAULT_HADOOP_JETTY_LOGS_SERVE_ALIASES)) {
+        logContext.getInitParams().put(
+            "org.mortbay.jetty.servlet.Default.aliases", "true");
+      }
+      logContext.setDisplayName("logs");
+      setContextAttributes(logContext, conf);
+      addNoCacheFilter(webAppContext);
+      defaultContexts.put(logContext, true);
+    }
+    // set up the context for "/static/*"
+    Context staticContext = new Context(parent, "/static");
+    staticContext.setResourceBase(appDir + "/static");
+    staticContext.addServlet(DefaultServlet.class, "/*");
+    staticContext.setDisplayName("static");
+    setContextAttributes(staticContext, conf);
+    defaultContexts.put(staticContext, true);
+  }
+  
+  private void setContextAttributes(Context context, Configuration conf) {
+    context.getServletContext().setAttribute(CONF_CONTEXT_ATTRIBUTE, conf);
+    context.getServletContext().setAttribute(ADMINS_ACL, adminsAcl);
+  }
+
+  /**
+   * Add default servlets.
+   */
+  protected void addDefaultServlets() {
+    // set up default servlets
+    addServlet("stacks", "/stacks", StackServlet.class);
+    addServlet("logLevel", "/logLevel", LogLevel.Servlet.class);
+    addServlet("metrics", "/metrics", MetricsServlet.class);
+    addServlet("jmx", "/jmx", JMXJsonServlet.class);
+    addServlet("conf", "/conf", ConfServlet.class);
+  }
+
+  public void addContext(Context ctxt, boolean isFiltered)
+      throws IOException {
+    webServer.addHandler(ctxt);
+    addNoCacheFilter(webAppContext);
+    defaultContexts.put(ctxt, isFiltered);
+  }
+
+  /**
+   * Add a context 
+   * @param pathSpec The path spec for the context
+   * @param dir The directory containing the context
+   * @param isFiltered if true, the servlet is added to the filter path mapping 
+   * @throws IOException
+   */
+  protected void addContext(String pathSpec, String dir, boolean isFiltered) throws IOException {
+    if (0 == webServer.getHandlers().length) {
+      throw new RuntimeException("Couldn't find handler");
+    }
+    WebAppContext webAppCtx = new WebAppContext();
+    webAppCtx.setContextPath(pathSpec);
+    webAppCtx.setWar(dir);
+    addContext(webAppCtx, true);
+  }
+
+  /**
+   * Set a value in the webapp context. These values are available to the jsp
+   * pages as "application.getAttribute(name)".
+   * @param name The name of the attribute
+   * @param value The value of the attribute
+   */
+  public void setAttribute(String name, Object value) {
+    webAppContext.setAttribute(name, value);
+  }
+
+  /** 
+   * Add a Jersey resource package.
+   * @param packageName The Java package name containing the Jersey resource.
+   * @param pathSpec The path spec for the servlet
+   */
+  public void addJerseyResourcePackage(final String packageName,
+      final String pathSpec) {
+    LOG.info("addJerseyResourcePackage: packageName=" + packageName
+        + ", pathSpec=" + pathSpec);
+    final ServletHolder sh = new ServletHolder(ServletContainer.class);
+    sh.setInitParameter("com.sun.jersey.config.property.resourceConfigClass",
+        "com.sun.jersey.api.core.PackagesResourceConfig");
+    sh.setInitParameter("com.sun.jersey.config.property.packages", packageName);
+    webAppContext.addServlet(sh, pathSpec);
+  }
+
+  /**
+   * Add a servlet in the server.
+   * @param name The name of the servlet (can be passed as null)
+   * @param pathSpec The path spec for the servlet
+   * @param clazz The servlet class
+   */
+  public void addServlet(String name, String pathSpec,
+      Class<? extends HttpServlet> clazz) {
+    addInternalServlet(name, pathSpec, clazz, false);
+    addFilterPathMapping(pathSpec, webAppContext);
+  }
+
+  /**
+   * Add an internal servlet in the server. 
+   * Note: This method is to be used for adding servlets that facilitate
+   * internal communication and not for user facing functionality. For
+   * servlets added using this method, filters are not enabled. 
+   * 
+   * @param name The name of the servlet (can be passed as null)
+   * @param pathSpec The path spec for the servlet
+   * @param clazz The servlet class
+   */
+  public void addInternalServlet(String name, String pathSpec,
+      Class<? extends HttpServlet> clazz) {
+    addInternalServlet(name, pathSpec, clazz, false);
+  }
+
+  /**
+   * Add an internal servlet in the server, specifying whether or not to
+   * protect with Kerberos authentication. 
+   * Note: This method is to be used for adding servlets that facilitate
+   * internal communication and not for user facing functionality. For
+   +   * servlets added using this method, filters (except internal Kerberos
+   * filters) are not enabled. 
+   * 
+   * @param name The name of the servlet (can be passed as null)
+   * @param pathSpec The path spec for the servlet
+   * @param clazz The servlet class
+   * @param requireAuth Require Kerberos authenticate to access servlet
+   */
+  public void addInternalServlet(String name, String pathSpec, 
+      Class<? extends HttpServlet> clazz, boolean requireAuth) {
+    ServletHolder holder = new ServletHolder(clazz);
+    if (name != null) {
+      holder.setName(name);
+    }
+    webAppContext.addServlet(holder, pathSpec);
+
+    if(requireAuth && UserGroupInformation.isSecurityEnabled()) {
+       LOG.info("Adding Kerberos (SPNEGO) filter to " + name);
+       ServletHandler handler = webAppContext.getServletHandler();
+       FilterMapping fmap = new FilterMapping();
+       fmap.setPathSpec(pathSpec);
+       fmap.setFilterName(SPNEGO_FILTER);
+       fmap.setDispatches(Handler.ALL);
+       handler.addFilterMapping(fmap);
+    }
+  }
+
+  @Override
+  public void addFilter(String name, String classname,
+      Map<String, String> parameters) {
+
+    final String[] USER_FACING_URLS = { "*.html", "*.jsp" };
+    defineFilter(webAppContext, name, classname, parameters, USER_FACING_URLS);
+    LOG.info("Added filter " + name + " (class=" + classname
+        + ") to context " + webAppContext.getDisplayName());
+    final String[] ALL_URLS = { "/*" };
+    for (Map.Entry<Context, Boolean> e : defaultContexts.entrySet()) {
+      if (e.getValue()) {
+        Context ctx = e.getKey();
+        defineFilter(ctx, name, classname, parameters, ALL_URLS);
+        LOG.info("Added filter " + name + " (class=" + classname
+            + ") to context " + ctx.getDisplayName());
+      }
+    }
+    filterNames.add(name);
+  }
+
+  @Override
+  public void addGlobalFilter(String name, String classname,
+      Map<String, String> parameters) {
+    final String[] ALL_URLS = { "/*" };
+    defineFilter(webAppContext, name, classname, parameters, ALL_URLS);
+    for (Context ctx : defaultContexts.keySet()) {
+      defineFilter(ctx, name, classname, parameters, ALL_URLS);
+    }
+    LOG.info("Added global filter '" + name + "' (class=" + classname + ")");
+  }
+
+  /**
+   * Define a filter for a context and set up default url mappings.
+   */
+  public void defineFilter(Context ctx, String name,
+      String classname, Map<String,String> parameters, String[] urls) {
+
+    FilterHolder holder = new FilterHolder();
+    holder.setName(name);
+    holder.setClassName(classname);
+    holder.setInitParameters(parameters);
+    FilterMapping fmap = new FilterMapping();
+    fmap.setPathSpecs(urls);
+    fmap.setDispatches(Handler.ALL);
+    fmap.setFilterName(name);
+    ServletHandler handler = ctx.getServletHandler();
+    handler.addFilter(holder, fmap);
+  }
+
+  /**
+   * Add the path spec to the filter path mapping.
+   * @param pathSpec The path spec
+   * @param webAppCtx The WebApplicationContext to add to
+   */
+  protected void addFilterPathMapping(String pathSpec,
+      Context webAppCtx) {
+    ServletHandler handler = webAppCtx.getServletHandler();
+    for(String name : filterNames) {
+      FilterMapping fmap = new FilterMapping();
+      fmap.setPathSpec(pathSpec);
+      fmap.setFilterName(name);
+      fmap.setDispatches(Handler.ALL);
+      handler.addFilterMapping(fmap);
+    }
+  }
+  
+  /**
+   * Get the value in the webapp context.
+   * @param name The name of the attribute
+   * @return The value of the attribute
+   */
+  public Object getAttribute(String name) {
+    return webAppContext.getAttribute(name);
+  }
+
+  public WebAppContext getWebAppContext(){
+    return this.webAppContext;
+  }
+
+  /**
+   * Get the pathname to the webapps files.
+   * @param appName eg "secondary" or "datanode"
+   * @return the pathname as a URL
+   * @throws FileNotFoundException if 'webapps' directory cannot be found on CLASSPATH.
+   */
+  protected String getWebAppsPath(String appName) throws FileNotFoundException {
+    URL url = getClass().getClassLoader().getResource("webapps/" + appName);
+    if (url == null) 
+      throw new FileNotFoundException("webapps/" + appName
+          + " not found in CLASSPATH");
+    String urlString = url.toString();
+    return urlString.substring(0, urlString.lastIndexOf('/'));
+  }
+
+  /**
+   * Get the port that the server is on
+   * @return the port
+   */
+  public int getPort() {
+    return webServer.getConnectors()[0].getLocalPort();
+  }
+
+  /**
+   * Set the min, max number of worker threads (simultaneous connections).
+   */
+  public void setThreads(int min, int max) {
+    QueuedThreadPool pool = (QueuedThreadPool) webServer.getThreadPool() ;
+    pool.setMinThreads(min);
+    pool.setMaxThreads(max);
+  }
+
+  /**
+   * Configure an ssl listener on the server.
+   * @param addr address to listen on
+   * @param keystore location of the keystore
+   * @param storPass password for the keystore
+   * @param keyPass password for the key
+   * @deprecated Use {@link #addSslListener(InetSocketAddress, Configuration, boolean)}
+   */
+  @Deprecated
+  public void addSslListener(InetSocketAddress addr, String keystore,
+      String storPass, String keyPass) throws IOException {
+    if (webServer.isStarted()) {
+      throw new IOException("Failed to add ssl listener");
+    }
+    SslSocketConnector sslListener = new SslSocketConnector();
+    sslListener.setHost(addr.getHostName());
+    sslListener.setPort(addr.getPort());
+    sslListener.setKeystore(keystore);
+    sslListener.setPassword(storPass);
+    sslListener.setKeyPassword(keyPass);
+    webServer.addConnector(sslListener);
+  }
+
+  /**
+   * Configure an ssl listener on the server.
+   * @param addr address to listen on
+   * @param sslConf conf to retrieve ssl options
+   * @param needCertsAuth whether x509 certificate authentication is required
+   */
+  public void addSslListener(InetSocketAddress addr, Configuration sslConf,
+      boolean needCertsAuth) throws IOException {
+    if (webServer.isStarted()) {
+      throw new IOException("Failed to add ssl listener");
+    }
+    if (needCertsAuth) {
+      // setting up SSL truststore for authenticating clients
+      System.setProperty("javax.net.ssl.trustStore", sslConf.get(
+          "ssl.server.truststore.location", ""));
+      System.setProperty("javax.net.ssl.trustStorePassword", sslConf.get(
+          "ssl.server.truststore.password", ""));
+      System.setProperty("javax.net.ssl.trustStoreType", sslConf.get(
+          "ssl.server.truststore.type", "jks"));
+    }
+    SslSocketConnector sslListener = new SslSocketConnector();
+    sslListener.setHost(addr.getHostName());
+    sslListener.setPort(addr.getPort());
+    sslListener.setKeystore(sslConf.get("ssl.server.keystore.location"));
+    sslListener.setPassword(sslConf.get("ssl.server.keystore.password", ""));
+    sslListener.setKeyPassword(sslConf.get("ssl.server.keystore.keypassword", ""));
+    sslListener.setKeystoreType(sslConf.get("ssl.server.keystore.type", "jks"));
+    sslListener.setNeedClientAuth(needCertsAuth);
+    webServer.addConnector(sslListener);
+  }
+  
+  protected void initSpnego(Configuration conf,
+      String usernameConfKey, String keytabConfKey) throws IOException {
+    Map<String, String> params = new HashMap<String, String>();
+    String principalInConf = conf.get(usernameConfKey);
+    if (principalInConf != null && !principalInConf.isEmpty()) {
+      params.put("kerberos.principal",
+                 SecurityUtil.getServerPrincipal(principalInConf, listener.getHost()));
+    }
+    String httpKeytab = conf.get(keytabConfKey);
+    if (httpKeytab != null && !httpKeytab.isEmpty()) {
+      params.put("kerberos.keytab", httpKeytab);
+    }
+    params.put(AuthenticationFilter.AUTH_TYPE, "kerberos");
+  
+    defineFilter(webAppContext, SPNEGO_FILTER,
+                 AuthenticationFilter.class.getName(), params, null);
+  }
+
+  /**
+   * Start the server. Does not wait for the server to start.
+   */
+  public void start() throws IOException {
+    try {
+      try {
+        openListener();
+        LOG.info("Jetty bound to port " + listener.getLocalPort());
+        webServer.start();
+      } catch (IOException ex) {
+        LOG.info("HttpServer.start() threw a non Bind IOException", ex);
+        throw ex;
+      } catch (MultiException ex) {
+        LOG.info("HttpServer.start() threw a MultiException", ex);
+        throw ex;
+      }
+      // Make sure there is no handler failures.
+      Handler[] handlers = webServer.getHandlers();
+      for (int i = 0; i < handlers.length; i++) {
+        if (handlers[i].isFailed()) {
+          throw new IOException(
+              "Problem in starting http server. Server handlers failed");
+        }
+      }
+      // Make sure there are no errors initializing the context.
+      Throwable unavailableException = webAppContext.getUnavailableException();
+      if (unavailableException != null) {
+        // Have to stop the webserver, or else its non-daemon threads
+        // will hang forever.
+        webServer.stop();
+        throw new IOException("Unable to initialize WebAppContext",
+            unavailableException);
+      }
+    } catch (IOException e) {
+      throw e;
+    } catch (Exception e) {
+      throw new IOException("Problem starting http server", e);
+    }
+  }
+
+  /**
+   * Open the main listener for the server
+   * @throws Exception
+   */
+  void openListener() throws Exception {
+    if (listener.getLocalPort() != -1) { // it's already bound
+      return;
+    }
+    if (listenerStartedExternally) { // Expect that listener was started securely
+      throw new Exception("Expected webserver's listener to be started " +
+          "previously but wasn't");
+    }
+    int port = listener.getPort();
+    while (true) {
+      // jetty has a bug where you can't reopen a listener that previously
+      // failed to open w/o issuing a close first, even if the port is changed
+      try {
+        listener.close();
+        listener.open();
+        break;
+      } catch (BindException ex) {
+        if (port == 0 || !findPort) {
+          BindException be = new BindException(
+              "Port in use: " + listener.getHost() + ":" + listener.getPort());
+          be.initCause(ex);
+          throw be;
+        }
+      }
+      // try the next port number
+      listener.setPort(++port);
+      Thread.sleep(100);
+    }
+  }
+  
+  /**
+   * Return the bind address of the listener.
+   * @return InetSocketAddress of the listener
+   */
+  public InetSocketAddress getListenerAddress() {
+    int port = listener.getLocalPort();
+    if (port == -1) { // not bound, return requested port
+      port = listener.getPort();
+    }
+    return new InetSocketAddress(listener.getHost(), port);
+  }
+  
+  /**
+   * stop the server
+   */
+  public void stop() throws Exception {
+    MultiException exception = null;
+    try {
+      listener.close();
+    } catch (Exception e) {
+      LOG.error("Error while stopping listener for webapp"
+          + webAppContext.getDisplayName(), e);
+      exception = addMultiException(exception, e);
+    }
+
+    try {
+      if (sslFactory != null) {
+          sslFactory.destroy();
+      }
+    } catch (Exception e) {
+      LOG.error("Error while destroying the SSLFactory"
+          + webAppContext.getDisplayName(), e);
+      exception = addMultiException(exception, e);
+    }
+
+    try {
+      // clear & stop webAppContext attributes to avoid memory leaks.
+      webAppContext.clearAttributes();
+      webAppContext.stop();
+    } catch (Exception e) {
+      LOG.error("Error while stopping web app context for webapp "
+          + webAppContext.getDisplayName(), e);
+      exception = addMultiException(exception, e);
+    }
+    try {
+      webServer.stop();
+    } catch (Exception e) {
+      LOG.error("Error while stopping web server for webapp "
+          + webAppContext.getDisplayName(), e);
+      exception = addMultiException(exception, e);
+    }
+
+    if (exception != null) {
+      exception.ifExceptionThrow();
+    }
+
+  }
+
+  private MultiException addMultiException(MultiException exception, Exception e) {
+    if(exception == null){
+      exception = new MultiException();
+    }
+    exception.add(e);
+    return exception;
+  }
+
+  public void join() throws InterruptedException {
+    webServer.join();
+  }
+
+  /**
+   * Test for the availability of the web server
+   * @return true if the web server is started, false otherwise
+   */
+  public boolean isAlive() {
+    return webServer != null && webServer.isStarted();
+  }
+
+  /**
+   * Return the host and port of the HttpServer, if live
+   * @return the classname and any HTTP URL
+   */
+  @Override
+  public String toString() {
+    return listener != null ?
+        ("HttpServer at http://" + listener.getHost() + ":" + listener.getLocalPort() + "/"
+            + (isAlive() ? STATE_DESCRIPTION_ALIVE : STATE_DESCRIPTION_NOT_LIVE))
+        : "Inactive HttpServer";
+  }
+
+  /**
+   * Checks the user has privileges to access to instrumentation servlets.
+   * <p/>
+   * If <code>hadoop.security.instrumentation.requires.admin</code> is set to FALSE
+   * (default value) it always returns TRUE.
+   * <p/>
+   * If <code>hadoop.security.instrumentation.requires.admin</code> is set to TRUE
+   * it will check that if the current user is in the admin ACLS. If the user is
+   * in the admin ACLs it returns TRUE, otherwise it returns FALSE.
+   *
+   * @param servletContext the servlet context.
+   * @param request the servlet request.
+   * @param response the servlet response.
+   * @return TRUE/FALSE based on the logic decribed above.
+   */
+  public static boolean isInstrumentationAccessAllowed(
+    ServletContext servletContext, HttpServletRequest request,
+    HttpServletResponse response) throws IOException {
+    Configuration conf =
+      (Configuration) servletContext.getAttribute(CONF_CONTEXT_ATTRIBUTE);
+
+    boolean access = true;
+    boolean adminAccess = conf.getBoolean(
+      CommonConfigurationKeys.HADOOP_SECURITY_INSTRUMENTATION_REQUIRES_ADMIN,
+      false);
+    if (adminAccess) {
+      access = hasAdministratorAccess(servletContext, request, response);
+    }
+    return access;
+  }
+
+  /**
+   * Does the user sending the HttpServletRequest has the administrator ACLs? If
+   * it isn't the case, response will be modified to send an error to the user.
+   * 
+   * @param servletContext
+   * @param request
+   * @param response used to send the error response if user does not have admin access.
+   * @return true if admin-authorized, false otherwise
+   * @throws IOException
+   */
+  public static boolean hasAdministratorAccess(
+      ServletContext servletContext, HttpServletRequest request,
+      HttpServletResponse response) throws IOException {
+    Configuration conf =
+        (Configuration) servletContext.getAttribute(CONF_CONTEXT_ATTRIBUTE);
+    // If there is no authorization, anybody has administrator access.
+    if (!conf.getBoolean(
+        CommonConfigurationKeys.HADOOP_SECURITY_AUTHORIZATION, false)) {
+      return true;
+    }
+
+    String remoteUser = request.getRemoteUser();
+    if (remoteUser == null) {
+      response.sendError(HttpServletResponse.SC_UNAUTHORIZED,
+                         "Unauthenticated users are not " +
+                         "authorized to access this page.");
+      return false;
+    }
+    
+    if (servletContext.getAttribute(ADMINS_ACL) != null &&
+        !userHasAdministratorAccess(servletContext, remoteUser)) {
+      response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "User "
+          + remoteUser + " is unauthorized to access this page.");
+      return false;
+    }
+
+    return true;
+  }
+
+  /**
+   * Get the admin ACLs from the given ServletContext and check if the given
+   * user is in the ACL.
+   * 
+   * @param servletContext the context containing the admin ACL.
+   * @param remoteUser the remote user to check for.
+   * @return true if the user is present in the ACL, false if no ACL is set or
+   *         the user is not present
+   */
+  public static boolean userHasAdministratorAccess(ServletContext servletContext,
+      String remoteUser) {
+    AccessControlList adminsAcl = (AccessControlList) servletContext
+        .getAttribute(ADMINS_ACL);
+    UserGroupInformation remoteUserUGI =
+        UserGroupInformation.createRemoteUser(remoteUser);
+    return adminsAcl != null && adminsAcl.isUserAllowed(remoteUserUGI);
+  }
+
+  /**
+   * A very simple servlet to serve up a text representation of the current
+   * stack traces. It both returns the stacks to the caller and logs them.
+   * Currently the stack traces are done sequentially rather than exactly the
+   * same data.
+   */
+  public static class StackServlet extends HttpServlet {
+    private static final long serialVersionUID = -6284183679759467039L;
+
+    @Override
+    public void doGet(HttpServletRequest request, HttpServletResponse response)
+      throws ServletException, IOException {
+      if (!HttpServer.isInstrumentationAccessAllowed(getServletContext(),
+                                                     request, response)) {
+        return;
+      }
+      response.setContentType("text/plain; charset=UTF-8");
+      PrintWriter out = response.getWriter();
+      ReflectionUtils.printThreadInfo(out, "");
+      out.close();
+      ReflectionUtils.logThreadInfo(LOG, "jsp requested", 1);      
+    }
+  }
+  
+  /**
+   * A Servlet input filter that quotes all HTML active characters in the
+   * parameter names and values. The goal is to quote the characters to make
+   * all of the servlets resistant to cross-site scripting attacks.
+   */
+  public static class QuotingInputFilter implements Filter {
+    private FilterConfig config;
+
+    public static class RequestQuoter extends HttpServletRequestWrapper {
+      private final HttpServletRequest rawRequest;
+      public RequestQuoter(HttpServletRequest rawRequest) {
+        super(rawRequest);
+        this.rawRequest = rawRequest;
+      }
+      
+      /**
+       * Return the set of parameter names, quoting each name.
+       */
+      @SuppressWarnings("unchecked")
+      @Override
+      public Enumeration<String> getParameterNames() {
+        return new Enumeration<String>() {
+          private Enumeration<String> rawIterator =
+            rawRequest.getParameterNames();
+          @Override
+          public boolean hasMoreElements() {
+            return rawIterator.hasMoreElements();
+          }
+
+          @Override
+          public String nextElement() {
+            return HtmlQuoting.quoteHtmlChars(rawIterator.nextElement());
+          }
+        };
+      }
+      
+      /**
+       * Unquote the name and quote the value.
+       */
+      @Override
+      public String getParameter(String name) {
+        return HtmlQuoting.quoteHtmlChars(rawRequest.getParameter
+                                     (HtmlQuoting.unquoteHtmlChars(name)));
+      }
+      
+      @Override
+      public String[] getParameterValues(String name) {
+        String unquoteName = HtmlQuoting.unquoteHtmlChars(name);
+        String[] unquoteValue = rawRequest.getParameterValues(unquoteName);
+        if (unquoteValue == null) {
+          return null;
+        }
+        String[] result = new String[unquoteValue.length];
+        for(int i=0; i < result.length; ++i) {
+          result[i] = HtmlQuoting.quoteHtmlChars(unquoteValue[i]);
+        }
+        return result;
+      }
+
+      @SuppressWarnings("unchecked")
+      @Override
+      public Map<String, String[]> getParameterMap() {
+        Map<String, String[]> result = new HashMap<String,String[]>();
+        Map<String, String[]> raw = rawRequest.getParameterMap();
+        for (Map.Entry<String,String[]> item: raw.entrySet()) {
+          String[] rawValue = item.getValue();
+          String[] cookedValue = new String[rawValue.length];
+          for(int i=0; i< rawValue.length; ++i) {
+            cookedValue[i] = HtmlQuoting.quoteHtmlChars(rawValue[i]);
+          }
+          result.put(HtmlQuoting.quoteHtmlChars(item.getKey()), cookedValue);
+        }
+        return result;
+      }
+      
+      /**
+       * Quote the url so that users specifying the HOST HTTP header
+       * can't inject attacks.
+       */
+      @Override
+      public StringBuffer getRequestURL(){
+        String url = rawRequest.getRequestURL().toString();
+        return new StringBuffer(HtmlQuoting.quoteHtmlChars(url));
+      }
+      
+      /**
+       * Quote the server name so that users specifying the HOST HTTP header
+       * can't inject attacks.
+       */
+      @Override
+      public String getServerName() {
+        return HtmlQuoting.quoteHtmlChars(rawRequest.getServerName());
+      }
+    }
+
+    @Override
+    public void init(FilterConfig config) throws ServletException {
+      this.config = config;
+    }
+
+    @Override
+    public void destroy() {
+    }
+
+    @Override
+    public void doFilter(ServletRequest request, 
+                         ServletResponse response,
+                         FilterChain chain
+                         ) throws IOException, ServletException {
+      HttpServletRequestWrapper quoted = 
+        new RequestQuoter((HttpServletRequest) request);
+      HttpServletResponse httpResponse = (HttpServletResponse) response;
+
+      String mime = inferMimeType(request);
+      if (mime == null) {
+        httpResponse.setContentType("text/plain; charset=utf-8");
+      } else if (mime.startsWith("text/html")) {
+        // HTML with unspecified encoding, we want to
+        // force HTML with utf-8 encoding
+        // This is to avoid the following security issue:
+        // http://openmya.hacker.jp/hasegawa/security/utf7cs.html
+        httpResponse.setContentType("text/html; charset=utf-8");
+      } else if (mime.startsWith("application/xml")) {
+        httpResponse.setContentType("text/xml; charset=utf-8");
+      }
+      chain.doFilter(quoted, httpResponse);
+    }
+
+    /**
+     * Infer the mime type for the response based on the extension of the request
+     * URI. Returns null if unknown.
+     */
+    private String inferMimeType(ServletRequest request) {
+      String path = ((HttpServletRequest)request).getRequestURI();
+      ContextHandler.SContext sContext = (ContextHandler.SContext)config.getServletContext();
+      MimeTypes mimes = sContext.getContextHandler().getMimeTypes();
+      Buffer mimeBuffer = mimes.getMimeByExtension(path);
+      return (mimeBuffer == null) ? null : mimeBuffer.toString();
+    }
+
+  }
+}