001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.hadoop.jmx;
019
020 import java.io.IOException;
021 import java.io.PrintWriter;
022 import java.lang.management.ManagementFactory;
023 import java.lang.reflect.Array;
024 import java.util.Iterator;
025 import java.util.Set;
026
027 import javax.management.AttributeNotFoundException;
028 import javax.management.InstanceNotFoundException;
029 import javax.management.IntrospectionException;
030 import javax.management.MBeanAttributeInfo;
031 import javax.management.MBeanException;
032 import javax.management.MBeanInfo;
033 import javax.management.MBeanServer;
034 import javax.management.MalformedObjectNameException;
035 import javax.management.ObjectName;
036 import javax.management.ReflectionException;
037 import javax.management.RuntimeErrorException;
038 import javax.management.RuntimeMBeanException;
039 import javax.management.openmbean.CompositeData;
040 import javax.management.openmbean.CompositeType;
041 import javax.management.openmbean.TabularData;
042 import javax.servlet.ServletException;
043 import javax.servlet.http.HttpServlet;
044 import javax.servlet.http.HttpServletRequest;
045 import javax.servlet.http.HttpServletResponse;
046
047 import org.apache.commons.logging.Log;
048 import org.apache.commons.logging.LogFactory;
049 import org.apache.hadoop.http.HttpServer;
050 import org.codehaus.jackson.JsonFactory;
051 import org.codehaus.jackson.JsonGenerator;
052
053 /*
054 * This servlet is based off of the JMXProxyServlet from Tomcat 7.0.14. It has
055 * been rewritten to be read only and to output in a JSON format so it is not
056 * really that close to the original.
057 */
058 /**
059 * Provides Read only web access to JMX.
060 * <p>
061 * This servlet generally will be placed under the /jmx URL for each
062 * HttpServer. It provides read only
063 * access to JMX metrics. The optional <code>qry</code> parameter
064 * may be used to query only a subset of the JMX Beans. This query
065 * functionality is provided through the
066 * {@link MBeanServer#queryNames(ObjectName, javax.management.QueryExp)}
067 * method.
068 * <p>
069 * For example <code>http://.../jmx?qry=Hadoop:*</code> will return
070 * all hadoop metrics exposed through JMX.
071 * <p>
072 * The optional <code>get</code> parameter is used to query an specific
073 * attribute of a JMX bean. The format of the URL is
074 * <code>http://.../jmx?get=MXBeanName::AttributeName<code>
075 * <p>
076 * For example
077 * <code>
078 * http://../jmx?get=Hadoop:service=NameNode,name=NameNodeInfo::ClusterId
079 * </code> will return the cluster id of the namenode mxbean.
080 * <p>
081 * If the <code>qry</code> or the <code>get</code> parameter is not formatted
082 * correctly then a 400 BAD REQUEST http response code will be returned.
083 * <p>
084 * If a resouce such as a mbean or attribute can not be found,
085 * a 404 SC_NOT_FOUND http response code will be returned.
086 * <p>
087 * The return format is JSON and in the form
088 * <p>
089 * <code><pre>
090 * {
091 * "beans" : [
092 * {
093 * "name":"bean-name"
094 * ...
095 * }
096 * ]
097 * }
098 * </pre></code>
099 * <p>
100 * The servlet attempts to convert the the JMXBeans into JSON. Each
101 * bean's attributes will be converted to a JSON object member.
102 *
103 * If the attribute is a boolean, a number, a string, or an array
104 * it will be converted to the JSON equivalent.
105 *
106 * If the value is a {@link CompositeData} then it will be converted
107 * to a JSON object with the keys as the name of the JSON member and
108 * the value is converted following these same rules.
109 *
110 * If the value is a {@link TabularData} then it will be converted
111 * to an array of the {@link CompositeData} elements that it contains.
112 *
113 * All other objects will be converted to a string and output as such.
114 *
115 * The bean's name and modelerType will be returned for all beans.
116 */
117 public class JMXJsonServlet extends HttpServlet {
118 private static final Log LOG = LogFactory.getLog(JMXJsonServlet.class);
119
120 private static final long serialVersionUID = 1L;
121
122 // ----------------------------------------------------- Instance Variables
123 /**
124 * MBean server.
125 */
126 protected transient MBeanServer mBeanServer = null;
127
128 // --------------------------------------------------------- Public Methods
129 /**
130 * Initialize this servlet.
131 */
132 @Override
133 public void init() throws ServletException {
134 // Retrieve the MBean server
135 mBeanServer = ManagementFactory.getPlatformMBeanServer();
136 }
137
138 /**
139 * Process a GET request for the specified resource.
140 *
141 * @param request
142 * The servlet request we are processing
143 * @param response
144 * The servlet response we are creating
145 */
146 @Override
147 public void doGet(HttpServletRequest request, HttpServletResponse response) {
148 try {
149 if (!HttpServer.isInstrumentationAccessAllowed(getServletContext(),
150 request, response)) {
151 return;
152 }
153
154 response.setContentType("application/json; charset=utf8");
155
156 PrintWriter writer = response.getWriter();
157
158 JsonFactory jsonFactory = new JsonFactory();
159 JsonGenerator jg = jsonFactory.createJsonGenerator(writer);
160 jg.useDefaultPrettyPrinter();
161 jg.writeStartObject();
162 if (mBeanServer == null) {
163 jg.writeStringField("result", "ERROR");
164 jg.writeStringField("message", "No MBeanServer could be found");
165 jg.close();
166 LOG.error("No MBeanServer could be found.");
167 response.setStatus(HttpServletResponse.SC_NOT_FOUND);
168 return;
169 }
170
171 // query per mbean attribute
172 String getmethod = request.getParameter("get");
173 if (getmethod != null) {
174 String[] splitStrings = getmethod.split("\\:\\:");
175 if (splitStrings.length != 2) {
176 jg.writeStringField("result", "ERROR");
177 jg.writeStringField("message", "query format is not as expected.");
178 jg.close();
179 response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
180 return;
181 }
182 listBeans(jg, new ObjectName(splitStrings[0]), splitStrings[1],
183 response);
184 jg.close();
185 return;
186 }
187
188 // query per mbean
189 String qry = request.getParameter("qry");
190 if (qry == null) {
191 qry = "*:*";
192 }
193 listBeans(jg, new ObjectName(qry), null, response);
194 jg.close();
195
196 } catch ( IOException e ) {
197 LOG.error("Caught an exception while processing JMX request", e);
198 response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
199 } catch ( MalformedObjectNameException e ) {
200 LOG.error("Caught an exception while processing JMX request", e);
201 response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
202 }
203 }
204
205 // --------------------------------------------------------- Private Methods
206 private void listBeans(JsonGenerator jg, ObjectName qry, String attribute,
207 HttpServletResponse response)
208 throws IOException {
209 LOG.debug("Listing beans for "+qry);
210 Set<ObjectName> names = null;
211 names = mBeanServer.queryNames(qry, null);
212
213 jg.writeArrayFieldStart("beans");
214 Iterator<ObjectName> it = names.iterator();
215 while (it.hasNext()) {
216 ObjectName oname = it.next();
217 MBeanInfo minfo;
218 String code = "";
219 Object attributeinfo = null;
220 try {
221 minfo = mBeanServer.getMBeanInfo(oname);
222 code = minfo.getClassName();
223 String prs = "";
224 try {
225 if ("org.apache.commons.modeler.BaseModelMBean".equals(code)) {
226 prs = "modelerType";
227 code = (String) mBeanServer.getAttribute(oname, prs);
228 }
229 if (attribute!=null) {
230 prs = attribute;
231 attributeinfo = mBeanServer.getAttribute(oname, prs);
232 }
233 } catch (AttributeNotFoundException e) {
234 // If the modelerType attribute was not found, the class name is used
235 // instead.
236 LOG.error("getting attribute " + prs + " of " + oname
237 + " threw an exception", e);
238 } catch (MBeanException e) {
239 // The code inside the attribute getter threw an exception so log it,
240 // and fall back on the class name
241 LOG.error("getting attribute " + prs + " of " + oname
242 + " threw an exception", e);
243 } catch (RuntimeException e) {
244 // For some reason even with an MBeanException available to them
245 // Runtime exceptionscan still find their way through, so treat them
246 // the same as MBeanException
247 LOG.error("getting attribute " + prs + " of " + oname
248 + " threw an exception", e);
249 } catch ( ReflectionException e ) {
250 // This happens when the code inside the JMX bean (setter?? from the
251 // java docs) threw an exception, so log it and fall back on the
252 // class name
253 LOG.error("getting attribute " + prs + " of " + oname
254 + " threw an exception", e);
255 }
256 } catch (InstanceNotFoundException e) {
257 //Ignored for some reason the bean was not found so don't output it
258 continue;
259 } catch ( IntrospectionException e ) {
260 // This is an internal error, something odd happened with reflection so
261 // log it and don't output the bean.
262 LOG.error("Problem while trying to process JMX query: " + qry
263 + " with MBean " + oname, e);
264 continue;
265 } catch ( ReflectionException e ) {
266 // This happens when the code inside the JMX bean threw an exception, so
267 // log it and don't output the bean.
268 LOG.error("Problem while trying to process JMX query: " + qry
269 + " with MBean " + oname, e);
270 continue;
271 }
272
273 jg.writeStartObject();
274 jg.writeStringField("name", oname.toString());
275
276 jg.writeStringField("modelerType", code);
277 if ((attribute != null) && (attributeinfo == null)) {
278 jg.writeStringField("result", "ERROR");
279 jg.writeStringField("message", "No attribute with name " + attribute
280 + " was found.");
281 jg.writeEndObject();
282 jg.writeEndArray();
283 jg.close();
284 response.setStatus(HttpServletResponse.SC_NOT_FOUND);
285 return;
286 }
287
288 if (attribute != null) {
289 writeAttribute(jg, attribute, attributeinfo);
290 } else {
291 MBeanAttributeInfo attrs[] = minfo.getAttributes();
292 for (int i = 0; i < attrs.length; i++) {
293 writeAttribute(jg, oname, attrs[i]);
294 }
295 }
296 jg.writeEndObject();
297 }
298 jg.writeEndArray();
299 }
300
301 private void writeAttribute(JsonGenerator jg, ObjectName oname, MBeanAttributeInfo attr) throws IOException {
302 if (!attr.isReadable()) {
303 return;
304 }
305 String attName = attr.getName();
306 if ("modelerType".equals(attName)) {
307 return;
308 }
309 if (attName.indexOf("=") >= 0 || attName.indexOf(":") >= 0
310 || attName.indexOf(" ") >= 0) {
311 return;
312 }
313 Object value = null;
314 try {
315 value = mBeanServer.getAttribute(oname, attName);
316 } catch (RuntimeMBeanException e) {
317 // UnsupportedOperationExceptions happen in the normal course of business,
318 // so no need to log them as errors all the time.
319 if (e.getCause() instanceof UnsupportedOperationException) {
320 LOG.debug("getting attribute "+attName+" of "+oname+" threw an exception", e);
321 } else {
322 LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
323 }
324 return;
325 } catch (RuntimeErrorException e) {
326 // RuntimeErrorException happens when an unexpected failure occurs in getAttribute
327 // for example https://issues.apache.org/jira/browse/DAEMON-120
328 LOG.debug("getting attribute "+attName+" of "+oname+" threw an exception", e);
329 return;
330 } catch (AttributeNotFoundException e) {
331 //Ignored the attribute was not found, which should never happen because the bean
332 //just told us that it has this attribute, but if this happens just don't output
333 //the attribute.
334 return;
335 } catch (MBeanException e) {
336 //The code inside the attribute getter threw an exception so log it, and
337 // skip outputting the attribute
338 LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
339 return;
340 } catch (RuntimeException e) {
341 //For some reason even with an MBeanException available to them Runtime exceptions
342 //can still find their way through, so treat them the same as MBeanException
343 LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
344 return;
345 } catch (ReflectionException e) {
346 //This happens when the code inside the JMX bean (setter?? from the java docs)
347 //threw an exception, so log it and skip outputting the attribute
348 LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
349 return;
350 } catch (InstanceNotFoundException e) {
351 //Ignored the mbean itself was not found, which should never happen because we
352 //just accessed it (perhaps something unregistered in-between) but if this
353 //happens just don't output the attribute.
354 return;
355 }
356
357 writeAttribute(jg, attName, value);
358 }
359
360 private void writeAttribute(JsonGenerator jg, String attName, Object value) throws IOException {
361 jg.writeFieldName(attName);
362 writeObject(jg, value);
363 }
364
365 private void writeObject(JsonGenerator jg, Object value) throws IOException {
366 if(value == null) {
367 jg.writeNull();
368 } else {
369 Class<?> c = value.getClass();
370 if (c.isArray()) {
371 jg.writeStartArray();
372 int len = Array.getLength(value);
373 for (int j = 0; j < len; j++) {
374 Object item = Array.get(value, j);
375 writeObject(jg, item);
376 }
377 jg.writeEndArray();
378 } else if(value instanceof Number) {
379 Number n = (Number)value;
380 jg.writeNumber(n.toString());
381 } else if(value instanceof Boolean) {
382 Boolean b = (Boolean)value;
383 jg.writeBoolean(b);
384 } else if(value instanceof CompositeData) {
385 CompositeData cds = (CompositeData)value;
386 CompositeType comp = cds.getCompositeType();
387 Set<String> keys = comp.keySet();
388 jg.writeStartObject();
389 for(String key: keys) {
390 writeAttribute(jg, key, cds.get(key));
391 }
392 jg.writeEndObject();
393 } else if(value instanceof TabularData) {
394 TabularData tds = (TabularData)value;
395 jg.writeStartArray();
396 for(Object entry : tds.values()) {
397 writeObject(jg, entry);
398 }
399 jg.writeEndArray();
400 } else {
401 jg.writeString(value.toString());
402 }
403 }
404 }
405 }