org.apache.hadoop.hbase.http.jmx.JMXJsonServlet Maven / Gradle / Ivy
/*
* 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.hbase.http.jmx;
import java.io.IOException;
import java.io.PrintWriter;
import java.lang.management.ManagementFactory;
import java.util.Iterator;
import java.util.List;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;
import javax.management.openmbean.CompositeData;
import javax.management.openmbean.TabularData;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.hadoop.hbase.http.HttpServer;
import org.apache.hadoop.hbase.util.JSONBean;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hbase.thirdparty.com.google.common.base.Splitter;
/*
* This servlet is based off of the JMXProxyServlet from Tomcat 7.0.14. It has
* been rewritten to be read only and to output in a JSON format so it is not
* really that close to the original.
*/
/**
* Provides Read only web access to JMX.
*
* This servlet generally will be placed under the /jmx URL for each HttpServer. It provides read
* only access to JMX metrics. The optional qry parameter may be used to query only a
* subset of the JMX Beans. This query functionality is provided through the
* {@link MBeanServer#queryNames(ObjectName, javax.management.QueryExp)} method.
*
*
* For example http://.../jmx?qry=Hadoop:* will return all hadoop metrics exposed
* through JMX.
*
*
* The optional get parameter is used to query an specific attribute of a JMX bean. The
* format of the URL is http://.../jmx?get=MXBeanName::AttributeName
*
*
* For example
* http://../jmx?get=Hadoop:service=NameNode,name=NameNodeInfo::ClusterId
* will return the cluster id of the namenode mxbean.
*
*
* If we are not sure on the exact attribute and we want to get all the attributes that match one or
* more given pattern then the format is
* http://.../jmx?get=MXBeanName::*[RegExp1],*[RegExp2]
*
*
* For example
*
* http://../jmx?get=Hadoop:service=HBase,name=RegionServer,sub=Tables::[a-zA-z_0-9]*memStoreSize
*
*
* http://../jmx?get=Hadoop:service=HBase,name=RegionServer,sub=Tables::[a-zA-z_0-9]*memStoreSize,[a-zA-z_0-9]*storeFileSize
*
*
*
* If the qry or the get parameter is not formatted correctly then a 400
* BAD REQUEST http response code will be returned.
*
*
* If a resouce such as a mbean or attribute can not be found, a 404 SC_NOT_FOUND http response code
* will be returned.
*
*
* The return format is JSON and in the form
*
*
*
*
* {
* "beans" : [
* {
* "name":"bean-name"
* ...
* }
* ]
* }
*
*
*
* The servlet attempts to convert the the JMXBeans into JSON. Each bean's attributes will be
* converted to a JSON object member. If the attribute is a boolean, a number, a string, or an array
* it will be converted to the JSON equivalent. If the value is a {@link CompositeData} then it will
* be converted to a JSON object with the keys as the name of the JSON member and the value is
* converted following these same rules. If the value is a {@link TabularData} then it will be
* converted to an array of the {@link CompositeData} elements that it contains. All other objects
* will be converted to a string and output as such. The bean's name and modelerType will be
* returned for all beans. Optional paramater "callback" should be used to deliver JSONP response.
*
*/
@InterfaceAudience.Private
public class JMXJsonServlet extends HttpServlet {
private static final Logger LOG = LoggerFactory.getLogger(JMXJsonServlet.class);
private static final long serialVersionUID = 1L;
private static final String CALLBACK_PARAM = "callback";
/**
* If query string includes 'description', then we will emit bean and attribute descriptions to
* output IFF they are not null and IFF the description is not the same as the attribute name:
* i.e. specify a URL like so: /jmx?description=true
*/
private static final String INCLUDE_DESCRIPTION = "description";
/**
* MBean server.
*/
protected transient MBeanServer mBeanServer;
protected transient JSONBean jsonBeanWriter;
/**
* Initialize this servlet.
*/
@Override
public void init() throws ServletException {
// Retrieve the MBean server
mBeanServer = ManagementFactory.getPlatformMBeanServer();
this.jsonBeanWriter = new JSONBean();
}
/**
* Process a GET request for the specified resource. The servlet request we are processing The
* servlet response we are creating
*/
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
try {
if (!HttpServer.isInstrumentationAccessAllowed(getServletContext(), request, response)) {
return;
}
String jsonpcb = null;
PrintWriter writer = null;
JSONBean.Writer beanWriter = null;
try {
jsonpcb = checkCallbackName(request.getParameter(CALLBACK_PARAM));
writer = response.getWriter();
// "callback" parameter implies JSONP outpout
if (jsonpcb != null) {
response.setContentType("application/javascript; charset=utf8");
writer.write(jsonpcb + "(");
} else {
response.setContentType("application/json; charset=utf8");
}
beanWriter = this.jsonBeanWriter.open(writer);
// Should we output description on each attribute and bean?
boolean description = "true".equals(request.getParameter(INCLUDE_DESCRIPTION));
// query per mbean attribute
String getmethod = request.getParameter("get");
if (getmethod != null) {
List splitStrings = Splitter.onPattern("\\:\\:").splitToList(getmethod);
if (splitStrings.size() != 2) {
beanWriter.write("result", "ERROR");
beanWriter.write("message", "query format is not as expected.");
beanWriter.flush();
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
return;
}
Iterator i = splitStrings.iterator();
if (
beanWriter.write(this.mBeanServer, new ObjectName(i.next()), i.next(), description) != 0
) {
beanWriter.flush();
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
}
return;
}
// query per mbean
String qry = request.getParameter("qry");
if (qry == null) {
qry = "*:*";
}
String excl = request.getParameter("excl");
ObjectName excluded = excl == null ? null : new ObjectName(excl);
if (
beanWriter.write(this.mBeanServer, new ObjectName(qry), null, description, excluded) != 0
) {
beanWriter.flush();
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
}
} finally {
if (beanWriter != null) {
beanWriter.close();
}
if (jsonpcb != null) {
writer.write(");");
}
if (writer != null) {
writer.close();
}
}
} catch (IOException e) {
LOG.error("Caught an exception while processing JMX request", e);
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
} catch (MalformedObjectNameException e) {
LOG.error("Caught an exception while processing JMX request", e);
response.sendError(HttpServletResponse.SC_BAD_REQUEST);
}
}
/**
* Verifies that the callback property, if provided, is purely alphanumeric. This prevents a
* malicious callback name (that is javascript code) from being returned by the UI to an
* unsuspecting user.
* @param callbackName The callback name, can be null.
* @return The callback name
* @throws IOException If the name is disallowed.
*/
private String checkCallbackName(String callbackName) throws IOException {
if (null == callbackName) {
return null;
}
if (callbackName.matches("[A-Za-z0-9_]+")) {
return callbackName;
}
throw new IOException("'callback' must be alphanumeric");
}
}