001/** 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 019package org.apache.hadoop.conf; 020 021import org.apache.commons.logging.*; 022 023import org.apache.commons.lang.StringEscapeUtils; 024 025import java.util.Collection; 026import java.util.Enumeration; 027import java.io.IOException; 028import java.io.PrintWriter; 029 030import javax.servlet.ServletException; 031import javax.servlet.http.HttpServlet; 032import javax.servlet.http.HttpServletRequest; 033import javax.servlet.http.HttpServletResponse; 034 035import org.apache.hadoop.util.StringUtils; 036 037/** 038 * A servlet for changing a node's configuration. 039 * 040 * Reloads the configuration file, verifies whether changes are 041 * possible and asks the admin to approve the change. 042 * 043 */ 044public class ReconfigurationServlet extends HttpServlet { 045 046 private static final long serialVersionUID = 1L; 047 048 private static final Log LOG = 049 LogFactory.getLog(ReconfigurationServlet.class); 050 051 // the prefix used to fing the attribute holding the reconfigurable 052 // for a given request 053 // 054 // we get the attribute prefix + servlet path 055 public static final String CONF_SERVLET_RECONFIGURABLE_PREFIX = 056 "conf.servlet.reconfigurable."; 057 058 @Override 059 public void init() throws ServletException { 060 super.init(); 061 } 062 063 private Reconfigurable getReconfigurable(HttpServletRequest req) { 064 LOG.info("servlet path: " + req.getServletPath()); 065 LOG.info("getting attribute: " + CONF_SERVLET_RECONFIGURABLE_PREFIX + 066 req.getServletPath()); 067 return (Reconfigurable) 068 this.getServletContext().getAttribute(CONF_SERVLET_RECONFIGURABLE_PREFIX + 069 req.getServletPath()); 070 } 071 072 private void printHeader(PrintWriter out, String nodeName) { 073 out.print("<html><head>"); 074 out.printf("<title>%s Reconfiguration Utility</title>%n", 075 StringEscapeUtils.escapeHtml(nodeName)); 076 out.print("</head><body>\n"); 077 out.printf("<h1>%s Reconfiguration Utility</h1>%n", 078 StringEscapeUtils.escapeHtml(nodeName)); 079 } 080 081 private void printFooter(PrintWriter out) { 082 out.print("</body></html>\n"); 083 } 084 085 /** 086 * Print configuration options that can be changed. 087 */ 088 private void printConf(PrintWriter out, Reconfigurable reconf) { 089 Configuration oldConf = reconf.getConf(); 090 Configuration newConf = new Configuration(); 091 092 Collection<ReconfigurationUtil.PropertyChange> changes = 093 ReconfigurationUtil.getChangedProperties(newConf, 094 oldConf); 095 096 boolean changeOK = true; 097 098 out.println("<form action=\"\" method=\"post\">"); 099 out.println("<table border=\"1\">"); 100 out.println("<tr><th>Property</th><th>Old value</th>"); 101 out.println("<th>New value </th><th></th></tr>"); 102 for (ReconfigurationUtil.PropertyChange c: changes) { 103 out.print("<tr><td>"); 104 if (!reconf.isPropertyReconfigurable(c.prop)) { 105 out.print("<font color=\"red\">" + 106 StringEscapeUtils.escapeHtml(c.prop) + "</font>"); 107 changeOK = false; 108 } else { 109 out.print(StringEscapeUtils.escapeHtml(c.prop)); 110 out.print("<input type=\"hidden\" name=\"" + 111 StringEscapeUtils.escapeHtml(c.prop) + "\" value=\"" + 112 StringEscapeUtils.escapeHtml(c.newVal) + "\"/>"); 113 } 114 out.print("</td><td>" + 115 (c.oldVal == null ? "<it>default</it>" : 116 StringEscapeUtils.escapeHtml(c.oldVal)) + 117 "</td><td>" + 118 (c.newVal == null ? "<it>default</it>" : 119 StringEscapeUtils.escapeHtml(c.newVal)) + 120 "</td>"); 121 out.print("</tr>\n"); 122 } 123 out.println("</table>"); 124 if (!changeOK) { 125 out.println("<p><font color=\"red\">WARNING: properties marked red" + 126 " will not be changed until the next restart.</font></p>"); 127 } 128 out.println("<input type=\"submit\" value=\"Apply\" />"); 129 out.println("</form>"); 130 } 131 132 @SuppressWarnings("unchecked") 133 private Enumeration<String> getParams(HttpServletRequest req) { 134 return req.getParameterNames(); 135 } 136 137 /** 138 * Apply configuratio changes after admin has approved them. 139 */ 140 private void applyChanges(PrintWriter out, Reconfigurable reconf, 141 HttpServletRequest req) throws ReconfigurationException { 142 Configuration oldConf = reconf.getConf(); 143 Configuration newConf = new Configuration(); 144 145 Enumeration<String> params = getParams(req); 146 147 synchronized(oldConf) { 148 while (params.hasMoreElements()) { 149 String rawParam = params.nextElement(); 150 String param = StringEscapeUtils.unescapeHtml(rawParam); 151 String value = 152 StringEscapeUtils.unescapeHtml(req.getParameter(rawParam)); 153 if (value != null) { 154 if (value.equals(newConf.getRaw(param)) || value.equals("default") || 155 value.equals("null") || value.isEmpty()) { 156 if ((value.equals("default") || value.equals("null") || 157 value.isEmpty()) && 158 oldConf.getRaw(param) != null) { 159 out.println("<p>Changed \"" + 160 StringEscapeUtils.escapeHtml(param) + "\" from \"" + 161 StringEscapeUtils.escapeHtml(oldConf.getRaw(param)) + 162 "\" to default</p>"); 163 reconf.reconfigureProperty(param, null); 164 } else if (!value.equals("default") && !value.equals("null") && 165 !value.isEmpty() && 166 (oldConf.getRaw(param) == null || 167 !oldConf.getRaw(param).equals(value))) { 168 // change from default or value to different value 169 if (oldConf.getRaw(param) == null) { 170 out.println("<p>Changed \"" + 171 StringEscapeUtils.escapeHtml(param) + 172 "\" from default to \"" + 173 StringEscapeUtils.escapeHtml(value) + "\"</p>"); 174 } else { 175 out.println("<p>Changed \"" + 176 StringEscapeUtils.escapeHtml(param) + "\" from \"" + 177 StringEscapeUtils.escapeHtml(oldConf. 178 getRaw(param)) + 179 "\" to \"" + 180 StringEscapeUtils.escapeHtml(value) + "\"</p>"); 181 } 182 reconf.reconfigureProperty(param, value); 183 } else { 184 LOG.info("property " + param + " unchanged"); 185 } 186 } else { 187 // parameter value != newConf value 188 out.println("<p>\"" + StringEscapeUtils.escapeHtml(param) + 189 "\" not changed because value has changed from \"" + 190 StringEscapeUtils.escapeHtml(value) + "\" to \"" + 191 StringEscapeUtils.escapeHtml(newConf.getRaw(param)) + 192 "\" since approval</p>"); 193 } 194 } 195 } 196 } 197 } 198 199 @Override 200 protected void doGet(HttpServletRequest req, HttpServletResponse resp) 201 throws ServletException, IOException { 202 LOG.info("GET"); 203 resp.setContentType("text/html"); 204 PrintWriter out = resp.getWriter(); 205 206 Reconfigurable reconf = getReconfigurable(req); 207 String nodeName = reconf.getClass().getCanonicalName(); 208 209 printHeader(out, nodeName); 210 printConf(out, reconf); 211 printFooter(out); 212 } 213 214 @Override 215 protected void doPost(HttpServletRequest req, HttpServletResponse resp) 216 throws ServletException, IOException { 217 LOG.info("POST"); 218 resp.setContentType("text/html"); 219 PrintWriter out = resp.getWriter(); 220 221 Reconfigurable reconf = getReconfigurable(req); 222 String nodeName = reconf.getClass().getCanonicalName(); 223 224 printHeader(out, nodeName); 225 226 try { 227 applyChanges(out, reconf, req); 228 } catch (ReconfigurationException e) { 229 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, 230 StringUtils.stringifyException(e)); 231 return; 232 } 233 234 out.println("<p><a href=\"" + req.getServletPath() + "\">back</a></p>"); 235 printFooter(out); 236 } 237 238}