| /** |
| * 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.conf; |
| |
| import java.io.IOException; |
| import java.io.Writer; |
| |
| import javax.servlet.ServletException; |
| import javax.servlet.http.HttpServlet; |
| import javax.servlet.http.HttpServletRequest; |
| import javax.servlet.http.HttpServletResponse; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.http.HttpServer2; |
| |
| /** |
| * A servlet to print out the running configuration data. |
| */ |
| @InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"}) |
| @InterfaceStability.Unstable |
| public class ConfServlet extends HttpServlet { |
| private static final long serialVersionUID = 1L; |
| |
| private static final String FORMAT_JSON = "json"; |
| private static final String FORMAT_XML = "xml"; |
| private static final String FORMAT_PARAM = "format"; |
| |
| /** |
| * Return the Configuration of the daemon hosting this servlet. |
| * This is populated when the HttpServer starts. |
| */ |
| private Configuration getConfFromContext() { |
| Configuration conf = (Configuration)getServletContext().getAttribute( |
| HttpServer2.CONF_CONTEXT_ATTRIBUTE); |
| assert conf != null; |
| return conf; |
| } |
| |
| @Override |
| public void doGet(HttpServletRequest request, HttpServletResponse response) |
| throws ServletException, IOException { |
| |
| if (!HttpServer2.isInstrumentationAccessAllowed(getServletContext(), |
| request, response)) { |
| return; |
| } |
| |
| String format = request.getParameter(FORMAT_PARAM); |
| if (null == format) { |
| format = FORMAT_XML; |
| } |
| |
| if (FORMAT_XML.equals(format)) { |
| response.setContentType("text/xml; charset=utf-8"); |
| } else if (FORMAT_JSON.equals(format)) { |
| response.setContentType("application/json; charset=utf-8"); |
| } |
| |
| Writer out = response.getWriter(); |
| try { |
| writeResponse(getConfFromContext(), out, format); |
| } catch (BadFormatException bfe) { |
| response.sendError(HttpServletResponse.SC_BAD_REQUEST, bfe.getMessage()); |
| } |
| out.close(); |
| } |
| |
| /** |
| * Guts of the servlet - extracted for easy testing. |
| */ |
| static void writeResponse(Configuration conf, Writer out, String format) |
| throws IOException, BadFormatException { |
| if (FORMAT_JSON.equals(format)) { |
| Configuration.dumpConfiguration(conf, out); |
| } else if (FORMAT_XML.equals(format)) { |
| conf.writeXml(out); |
| } else { |
| throw new BadFormatException("Bad format: " + format); |
| } |
| } |
| |
| public static class BadFormatException extends Exception { |
| private static final long serialVersionUID = 1L; |
| |
| public BadFormatException(String msg) { |
| super(msg); |
| } |
| } |
| |
| } |