z2-Environment

/*

 * 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.jmx;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.apache.hadoop.http.HttpServer2;

import org.codehaus.jackson.JsonFactory;

import org.codehaus.jackson.JsonGenerator;

import javax.management.AttributeNotFoundException;

import javax.management.InstanceNotFoundException;

import javax.management.IntrospectionException;

import javax.management.MBeanAttributeInfo;

import javax.management.MBeanException;

import javax.management.MBeanInfo;

import javax.management.MBeanServer;

import javax.management.MalformedObjectNameException;

import javax.management.ObjectName;

import javax.management.ReflectionException;

import javax.management.RuntimeErrorException;

import javax.management.RuntimeMBeanException;

import javax.management.openmbean.CompositeData;

import javax.management.openmbean.CompositeType;

import javax.management.openmbean.TabularData;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.io.PrintWriter;

import java.lang.management.ManagementFactory;

import java.lang.reflect.Array;

import java.util.Iterator;

import java.util.Set;

/*

 * 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.

 * <p>

 * This servlet generally will be placed under the /jmx URL for each

 * HttpServer.  It provides read only

 * access to JMX metrics.  The optional <code>qry</code> 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.

 * <p>

 * For example <code>http://.../jmx?qry=Hadoop:*</code> will return

 * all hadoop metrics exposed through JMX.

 * <p>

 * The optional <code>get</code> parameter is used to query an specific 

 * attribute of a JMX bean.  The format of the URL is

 * <code>http://.../jmx?get=MXBeanName::AttributeName<code>

 * <p>

 * For example 

 * <code>

 * http://../jmx?get=Hadoop:service=NameNode,name=NameNodeInfo::ClusterId

 * </code> will return the cluster id of the namenode mxbean.

 * <p>

 * If the <code>qry</code> or the <code>get</code> parameter is not formatted 

 * correctly then a 400 BAD REQUEST http response code will be returned. 

 * <p>

 * If a resouce such as a mbean or attribute can not be found, 

 * a 404 SC_NOT_FOUND http response code will be returned. 

 * <p>

 * The return format is JSON and in the form

 * <p>

 *  <code><pre>

 *  {

 *    "beans" : [

 *      {

 *        "name":"bean-name"

 *        ...

 *      }

 *    ]

 *  }

 *  </pre></code>

 *  <p>

 *  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.

 *

 */

public class JMXJsonServlet extends HttpServlet {

  private static final Log LOG = LogFactory.getLog(JMXJsonServlet.class);

  static final String ACCESS_CONTROL_ALLOW_METHODS =

      "Access-Control-Allow-Methods";

  static final String ACCESS_CONTROL_ALLOW_ORIGIN =

      "Access-Control-Allow-Origin";

  private static final long serialVersionUID = 1L;

  /**

   * MBean server.

   */

  protected transient MBeanServer mBeanServer = null;

  // --------------------------------------------------------- Public Methods

  /**

   * Initialize this servlet.

   */

  @Override

  public void init() throws ServletException {

    // Retrieve the MBean server

    mBeanServer = ManagementFactory.getPlatformMBeanServer();

  }

  protected boolean isInstrumentationAccessAllowed(HttpServletRequest request,

      HttpServletResponse response) throws IOException {

    return HttpServer2.isInstrumentationAccessAllowed(getServletContext(),

        request, response);

  }

  /**

   * Disable TRACE method to avoid TRACE vulnerability.

   */

  @Override

  protected void doTrace(HttpServletRequest req, HttpServletResponse resp)

      throws ServletException, IOException {

    resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED);

  }

  /**

   * Process a GET request for the specified resource.

   * 

   * @param request

   *          The servlet request we are processing

   * @param response

   *          The servlet response we are creating

   */

  @Override

  public void doGet(HttpServletRequest request, HttpServletResponse response) {

    String jsonpcb = null;

    PrintWriter writer = null;

    try {

      // If user is a static user and auth Type is null, that means

      // there is a non-security environment and no need authorization,

      // otherwise, do the authorization.

      final ServletContext servletContext = getServletContext();

      if (!HttpServer2.isStaticUserAndNoneAuthType(servletContext, request) &&

          !isInstrumentationAccessAllowed(request, response)) {

        return;

      }

      JsonGenerator jg = null;

      try {

        writer = response.getWriter();

        response.setContentType("application/json; charset=utf8");

        response.setHeader(ACCESS_CONTROL_ALLOW_METHODS, "GET");

        response.setHeader(ACCESS_CONTROL_ALLOW_ORIGIN, "*");

      JsonFactory jsonFactory = new JsonFactory();

      jg = jsonFactory.createJsonGenerator(writer);

      jg.disable(JsonGenerator.Feature.AUTO_CLOSE_TARGET);

      jg.useDefaultPrettyPrinter();

      jg.writeStartObject();

      if (mBeanServer == null) {

        jg.writeStringField("result", "ERROR");

        jg.writeStringField("message", "No MBeanServer could be found");

        jg.close();

        LOG.error("No MBeanServer could be found.");

        response.setStatus(HttpServletResponse.SC_NOT_FOUND);

        return;

      }

      // query per mbean attribute

      String getmethod = request.getParameter("get");

      if (getmethod != null) {

        String[] splitStrings = getmethod.split("\\:\\:");

        if (splitStrings.length != 2) {

          jg.writeStringField("result", "ERROR");

          jg.writeStringField("message", "query format is not as expected.");

          jg.close();

          response.setStatus(HttpServletResponse.SC_BAD_REQUEST);

          return;

        }

        listBeans(jg, new ObjectName(splitStrings[0]), splitStrings[1],

            response);

        jg.close();

        return;

      }

        // query per mbean

        String qry = request.getParameter("qry");

        if (qry == null) {

          qry = "*:*";

        }

        listBeans(jg, new ObjectName(qry), null, response);

      } finally {

        if (jg != null) {

          jg.close();

        }

        if (writer != null) {

          writer.close();

        }

      }

    } catch ( IOException e ) {

      LOG.error("Caught an exception while processing JMX request", e);

      response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);

    } catch ( MalformedObjectNameException e ) {

      LOG.error("Caught an exception while processing JMX request", e);

      response.setStatus(HttpServletResponse.SC_BAD_REQUEST);

    } finally {

      if (writer != null) {

        writer.close();

      }

    }

  }

  // --------------------------------------------------------- Private Methods

  private void listBeans(JsonGenerator jg, ObjectName qry, String attribute, 

      HttpServletResponse response) 

  throws IOException {

    LOG.debug("Listing beans for "+qry);

    Set<ObjectName> names = null;

    names = mBeanServer.queryNames(qry, null);

    jg.writeArrayFieldStart("beans");

    Iterator<ObjectName> it = names.iterator();

    while (it.hasNext()) {

      ObjectName oname = it.next();

      MBeanInfo minfo;

      String code = "";

      Object attributeinfo = null;

      try {

        minfo = mBeanServer.getMBeanInfo(oname);

        code = minfo.getClassName();

        String prs = "";

        try {

          if ("org.apache.commons.modeler.BaseModelMBean".equals(code)) {

            prs = "modelerType";

            code = (String) mBeanServer.getAttribute(oname, prs);

          }

          if (attribute!=null) {

            prs = attribute;

            attributeinfo = mBeanServer.getAttribute(oname, prs);

          }

        } catch (AttributeNotFoundException e) {

          // If the modelerType attribute was not found, the class name is used

          // instead.

          LOG.error("getting attribute " + prs + " of " + oname

              + " threw an exception", e);

        } catch (MBeanException e) {

          // The code inside the attribute getter threw an exception so log it,

          // and fall back on the class name

          LOG.error("getting attribute " + prs + " of " + oname

              + " threw an exception", e);

        } catch (RuntimeException e) {

          // For some reason even with an MBeanException available to them

          // Runtime exceptionscan still find their way through, so treat them

          // the same as MBeanException

          LOG.error("getting attribute " + prs + " of " + oname

              + " threw an exception", e);

        } catch ( ReflectionException e ) {

          // This happens when the code inside the JMX bean (setter?? from the

          // java docs) threw an exception, so log it and fall back on the 

          // class name

          LOG.error("getting attribute " + prs + " of " + oname

              + " threw an exception", e);

        }

      } catch (InstanceNotFoundException e) {

        //Ignored for some reason the bean was not found so don't output it

        continue;

      } catch ( IntrospectionException e ) {

        // This is an internal error, something odd happened with reflection so

        // log it and don't output the bean.

        LOG.error("Problem while trying to process JMX query: " + qry

            + " with MBean " + oname, e);

        continue;

      } catch ( ReflectionException e ) {

        // This happens when the code inside the JMX bean threw an exception, so

        // log it and don't output the bean.

        LOG.error("Problem while trying to process JMX query: " + qry

            + " with MBean " + oname, e);

        continue;

      }

      jg.writeStartObject();

      jg.writeStringField("name", oname.toString());

      jg.writeStringField("modelerType", code);

      if ((attribute != null) && (attributeinfo == null)) {

        jg.writeStringField("result", "ERROR");

        jg.writeStringField("message", "No attribute with name " + attribute

            + " was found.");

        jg.writeEndObject();

        jg.writeEndArray();

        jg.close();

        response.setStatus(HttpServletResponse.SC_NOT_FOUND);

        return;

      }

      if (attribute != null) {

        writeAttribute(jg, attribute, attributeinfo);

      } else {

        MBeanAttributeInfo attrs[] = minfo.getAttributes();

        for (int i = 0; i < attrs.length; i++) {

          writeAttribute(jg, oname, attrs[i]);

        }

      }

      jg.writeEndObject();

    }

    jg.writeEndArray();

  }

  private void writeAttribute(JsonGenerator jg, ObjectName oname, MBeanAttributeInfo attr) throws IOException {

    if (!attr.isReadable()) {

      return;

    }

    String attName = attr.getName();

    if ("modelerType".equals(attName)) {

      return;

    }

    if (attName.indexOf("=") >= 0 || attName.indexOf(":") >= 0

        || attName.indexOf(" ") >= 0) {

      return;

    }

    Object value = null;

    try {

      value = mBeanServer.getAttribute(oname, attName);

    } catch (RuntimeMBeanException e) {

      // UnsupportedOperationExceptions happen in the normal course of business,

      // so no need to log them as errors all the time.

      if (e.getCause() instanceof UnsupportedOperationException) {

        LOG.debug("getting attribute "+attName+" of "+oname+" threw an exception", e);

      } else {

        LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);

      }

      return;

    } catch (RuntimeErrorException e) {

      // RuntimeErrorException happens when an unexpected failure occurs in getAttribute

      // for example https://issues.apache.org/jira/browse/DAEMON-120

      LOG.debug("getting attribute "+attName+" of "+oname+" threw an exception", e);

      return;

    } catch (AttributeNotFoundException e) {

      //Ignored the attribute was not found, which should never happen because the bean

      //just told us that it has this attribute, but if this happens just don't output

      //the attribute.

      return;

    } catch (MBeanException e) {

      //The code inside the attribute getter threw an exception so log it, and

      // skip outputting the attribute

      LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);

      return;

    } catch (RuntimeException e) {

      //For some reason even with an MBeanException available to them Runtime exceptions

      //can still find their way through, so treat them the same as MBeanException

      LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);

      return;

    } catch (ReflectionException e) {

      //This happens when the code inside the JMX bean (setter?? from the java docs)

      //threw an exception, so log it and skip outputting the attribute

      LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);

      return;

    } catch (InstanceNotFoundException e) {

      //Ignored the mbean itself was not found, which should never happen because we

      //just accessed it (perhaps something unregistered in-between) but if this

      //happens just don't output the attribute.

      return;

    }

    writeAttribute(jg, attName, value);

  }

  private void writeAttribute(JsonGenerator jg, String attName, Object value) throws IOException {

    jg.writeFieldName(attName);

    writeObject(jg, value);

  }

  private void writeObject(JsonGenerator jg, Object value) throws IOException {

    if(value == null) {

      jg.writeNull();

    } else {

      Class<?> c = value.getClass();

      if (c.isArray()) {

        jg.writeStartArray();

        int len = Array.getLength(value);

        for (int j = 0; j < len; j++) {

          Object item = Array.get(value, j);

          writeObject(jg, item);

        }

        jg.writeEndArray();

      } else if(value instanceof Number) {

        Number n = (Number)value;

        jg.writeNumber(n.toString());

      } else if(value instanceof Boolean) {

        Boolean b = (Boolean)value;

        jg.writeBoolean(b);

      } else if(value instanceof CompositeData) {

        CompositeData cds = (CompositeData)value;

        CompositeType comp = cds.getCompositeType();

        Set<String> keys = comp.keySet();

        jg.writeStartObject();

        for(String key: keys) {

          writeAttribute(jg, key, cds.get(key));

        }

        jg.writeEndObject();

      } else if(value instanceof TabularData) {

        TabularData tds = (TabularData)value;

        jg.writeStartArray();

        for(Object entry : tds.values()) {

          writeObject(jg, entry);

        }

        jg.writeEndArray();

      } else {

        jg.writeString(value.toString());

      }

    }

  }

}