hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/ReconfigurationServlet.java - hadoop - Git at Google

 /**
  * 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 org.apache.commons.lang.StringEscapeUtils;

 import java.util.Collection;
 import java.util.Enumeration;
 import java.io.IOException;
 import java.io.PrintWriter;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import org.apache.hadoop.util.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 /**
  * A servlet for changing a node's configuration.
  *
  * Reloads the configuration file, verifies whether changes are
  * possible and asks the admin to approve the change.
  *
  */
 public class ReconfigurationServlet extends HttpServlet {

   private static final long serialVersionUID = 1L;

   private static final Logger LOG =
       LoggerFactory.getLogger(ReconfigurationServlet.class);

   // the prefix used to fing the attribute holding the reconfigurable
   // for a given request
   //
   // we get the attribute prefix + servlet path
   public static final String CONF_SERVLET_RECONFIGURABLE_PREFIX =
     "conf.servlet.reconfigurable.";

   @Override
   public void init() throws ServletException {
     super.init();
   }

   private Reconfigurable getReconfigurable(HttpServletRequest req) {
     LOG.info("servlet path: " + req.getServletPath());
     LOG.info("getting attribute: " + CONF_SERVLET_RECONFIGURABLE_PREFIX +
              req.getServletPath());
     return (Reconfigurable)
       this.getServletContext().getAttribute(CONF_SERVLET_RECONFIGURABLE_PREFIX +
                                             req.getServletPath());
   }

   private void printHeader(PrintWriter out, String nodeName) {
     out.print("<html><head>");
     out.printf("<title>%s Reconfiguration Utility</title>%n",
                StringEscapeUtils.escapeHtml(nodeName));
     out.print("</head><body>\n");
     out.printf("<h1>%s Reconfiguration Utility</h1>%n",
                StringEscapeUtils.escapeHtml(nodeName));
   }

   private void printFooter(PrintWriter out) {
     out.print("</body></html>\n");
   }

   /**
    * Print configuration options that can be changed.
    */
   private void printConf(PrintWriter out, Reconfigurable reconf) {
     Configuration oldConf = reconf.getConf();
     Configuration newConf = new Configuration();

     Collection<ReconfigurationUtil.PropertyChange> changes =
       ReconfigurationUtil.getChangedProperties(newConf,
                                                oldConf);

     boolean changeOK = true;

     out.println("<form action=\"\" method=\"post\">");
     out.println("<table border=\"1\">");
     out.println("<tr><th>Property</th><th>Old value</th>");
     out.println("<th>New value </th><th></th></tr>");
     for (ReconfigurationUtil.PropertyChange c: changes) {
       out.print("<tr><td>");
       if (!reconf.isPropertyReconfigurable(c.prop)) {
         out.print("<font color=\"red\">" +
                   StringEscapeUtils.escapeHtml(c.prop) + "</font>");
         changeOK = false;
       } else {
         out.print(StringEscapeUtils.escapeHtml(c.prop));
         out.print("<input type=\"hidden\" name=\"" +
                   StringEscapeUtils.escapeHtml(c.prop) + "\" value=\"" +
                   StringEscapeUtils.escapeHtml(c.newVal) + "\"/>");
       }
       out.print("</td><td>" +
                 (c.oldVal == null ? "<it>default</it>" :
                  StringEscapeUtils.escapeHtml(c.oldVal)) +
                 "</td><td>" +
                 (c.newVal == null ? "<it>default</it>" :
                  StringEscapeUtils.escapeHtml(c.newVal)) +
                 "</td>");
       out.print("</tr>\n");
     }
     out.println("</table>");
     if (!changeOK) {
       out.println("<p><font color=\"red\">WARNING: properties marked red" +
                   " will not be changed until the next restart.</font></p>");
     }
     out.println("<input type=\"submit\" value=\"Apply\" />");
     out.println("</form>");
   }

   @SuppressWarnings("unchecked")
   private Enumeration<String> getParams(HttpServletRequest req) {
     return req.getParameterNames();
   }

   /**
    * Apply configuratio changes after admin has approved them.
    */
   private void applyChanges(PrintWriter out, Reconfigurable reconf,
       HttpServletRequest req) throws ReconfigurationException {
     Configuration oldConf = reconf.getConf();
     Configuration newConf = new Configuration();

     Enumeration<String> params = getParams(req);

     synchronized(oldConf) {
       while (params.hasMoreElements()) {
         String rawParam = params.nextElement();
         String param = StringEscapeUtils.unescapeHtml(rawParam);
         String value =
           StringEscapeUtils.unescapeHtml(req.getParameter(rawParam));
         if (value != null) {
           if (value.equals(newConf.getRaw(param)) || value.equals("default") ||
               value.equals("null") || value.isEmpty()) {
             if ((value.equals("default") || value.equals("null") ||
                  value.isEmpty()) &&
                 oldConf.getRaw(param) != null) {
               out.println("<p>Changed \"" +
                           StringEscapeUtils.escapeHtml(param) + "\" from \"" +
                           StringEscapeUtils.escapeHtml(oldConf.getRaw(param)) +
                           "\" to default</p>");
               reconf.reconfigureProperty(param, null);
             } else if (!value.equals("default") && !value.equals("null") &&
                        !value.isEmpty() &&
                        (oldConf.getRaw(param) == null ||
                         !oldConf.getRaw(param).equals(value))) {
               // change from default or value to different value
               if (oldConf.getRaw(param) == null) {
                 out.println("<p>Changed \"" +
                             StringEscapeUtils.escapeHtml(param) +
                             "\" from default to \"" +
                             StringEscapeUtils.escapeHtml(value) + "\"</p>");
               } else {
                 out.println("<p>Changed \"" +
                             StringEscapeUtils.escapeHtml(param) + "\" from \"" +
                             StringEscapeUtils.escapeHtml(oldConf.
                                                          getRaw(param)) +
                             "\" to \"" +
                             StringEscapeUtils.escapeHtml(value) + "\"</p>");
               }
               reconf.reconfigureProperty(param, value);
             } else {
               LOG.info("property " + param + " unchanged");
             }
           } else {
             // parameter value != newConf value
             out.println("<p>\"" + StringEscapeUtils.escapeHtml(param) +
                         "\" not changed because value has changed from \"" +
                         StringEscapeUtils.escapeHtml(value) + "\" to \"" +
                         StringEscapeUtils.escapeHtml(newConf.getRaw(param)) +
                         "\" since approval</p>");
           }
         }
       }
     }
   }

   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse resp)
     throws ServletException, IOException {
     LOG.info("GET");
     resp.setContentType("text/html");
     PrintWriter out = resp.getWriter();

     Reconfigurable reconf = getReconfigurable(req);
     String nodeName = reconf.getClass().getCanonicalName();

     printHeader(out, nodeName);
     printConf(out, reconf);
     printFooter(out);
   }

   @Override
   protected void doPost(HttpServletRequest req, HttpServletResponse resp)
     throws ServletException, IOException {
     LOG.info("POST");
     resp.setContentType("text/html");
     PrintWriter out = resp.getWriter();

     Reconfigurable reconf = getReconfigurable(req);
     String nodeName = reconf.getClass().getCanonicalName();

     printHeader(out, nodeName);

     try {
       applyChanges(out, reconf, req);
     } catch (ReconfigurationException e) {
       resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
                      StringUtils.stringifyException(e));
       return;
     }

     out.println("<p><a href=\"" + req.getServletPath() + "\">back</a></p>");
     printFooter(out);
   }

 }
	/**
	* 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 org.apache.commons.lang.StringEscapeUtils;

	import java.util.Collection;
	import java.util.Enumeration;
	import java.io.IOException;
	import java.io.PrintWriter;

	import javax.servlet.ServletException;
	import javax.servlet.http.HttpServlet;
	import javax.servlet.http.HttpServletRequest;
	import javax.servlet.http.HttpServletResponse;

	import org.apache.hadoop.util.StringUtils;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;

	/**
	* A servlet for changing a node's configuration.
	*
	* Reloads the configuration file, verifies whether changes are
	* possible and asks the admin to approve the change.
	*
	*/
	public class ReconfigurationServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;

	private static final Logger LOG =
	LoggerFactory.getLogger(ReconfigurationServlet.class);

	// the prefix used to fing the attribute holding the reconfigurable
	// for a given request
	//
	// we get the attribute prefix + servlet path
	public static final String CONF_SERVLET_RECONFIGURABLE_PREFIX =
	"conf.servlet.reconfigurable.";

	@Override
	public void init() throws ServletException {
	super.init();
	}

	private Reconfigurable getReconfigurable(HttpServletRequest req) {
	LOG.info("servlet path: " + req.getServletPath());
	LOG.info("getting attribute: " + CONF_SERVLET_RECONFIGURABLE_PREFIX +
	req.getServletPath());
	return (Reconfigurable)
	this.getServletContext().getAttribute(CONF_SERVLET_RECONFIGURABLE_PREFIX +
	req.getServletPath());
	}

	private void printHeader(PrintWriter out, String nodeName) {
	out.print("<html><head>");
	out.printf("<title>%s Reconfiguration Utility</title>%n",
	StringEscapeUtils.escapeHtml(nodeName));
	out.print("</head><body>\n");
	out.printf("<h1>%s Reconfiguration Utility</h1>%n",
	StringEscapeUtils.escapeHtml(nodeName));
	}

	private void printFooter(PrintWriter out) {
	out.print("</body></html>\n");
	}

	/**
	* Print configuration options that can be changed.
	*/
	private void printConf(PrintWriter out, Reconfigurable reconf) {
	Configuration oldConf = reconf.getConf();
	Configuration newConf = new Configuration();

	Collection<ReconfigurationUtil.PropertyChange> changes =
	ReconfigurationUtil.getChangedProperties(newConf,
	oldConf);

	boolean changeOK = true;

	out.println("<form action=\"\" method=\"post\">");
	out.println("<table border=\"1\">");
	out.println("<tr><th>Property</th><th>Old value</th>");
	out.println("<th>New value </th><th></th></tr>");
	for (ReconfigurationUtil.PropertyChange c: changes) {
	out.print("<tr><td>");
	if (!reconf.isPropertyReconfigurable(c.prop)) {
	out.print("<font color=\"red\">" +
	StringEscapeUtils.escapeHtml(c.prop) + "</font>");
	changeOK = false;
	} else {
	out.print(StringEscapeUtils.escapeHtml(c.prop));
	out.print("<input type=\"hidden\" name=\"" +
	StringEscapeUtils.escapeHtml(c.prop) + "\" value=\"" +
	StringEscapeUtils.escapeHtml(c.newVal) + "\"/>");
	}
	out.print("</td><td>" +
	(c.oldVal == null ? "<it>default</it>" :
	StringEscapeUtils.escapeHtml(c.oldVal)) +
	"</td><td>" +
	(c.newVal == null ? "<it>default</it>" :
	StringEscapeUtils.escapeHtml(c.newVal)) +
	"</td>");
	out.print("</tr>\n");
	}
	out.println("</table>");
	if (!changeOK) {
	out.println("<p><font color=\"red\">WARNING: properties marked red" +
	" will not be changed until the next restart.</font></p>");
	}
	out.println("<input type=\"submit\" value=\"Apply\" />");
	out.println("</form>");
	}

	@SuppressWarnings("unchecked")
	private Enumeration<String> getParams(HttpServletRequest req) {
	return req.getParameterNames();
	}

	/**
	* Apply configuratio changes after admin has approved them.
	*/
	private void applyChanges(PrintWriter out, Reconfigurable reconf,
	HttpServletRequest req) throws ReconfigurationException {
	Configuration oldConf = reconf.getConf();
	Configuration newConf = new Configuration();

	Enumeration<String> params = getParams(req);

	synchronized(oldConf) {
	while (params.hasMoreElements()) {
	String rawParam = params.nextElement();
	String param = StringEscapeUtils.unescapeHtml(rawParam);
	String value =
	StringEscapeUtils.unescapeHtml(req.getParameter(rawParam));
	if (value != null) {
	if (value.equals(newConf.getRaw(param)) \|\| value.equals("default") \|\|
	value.equals("null") \|\| value.isEmpty()) {
	if ((value.equals("default") \|\| value.equals("null") \|\|
	value.isEmpty()) &&
	oldConf.getRaw(param) != null) {
	out.println("<p>Changed \"" +
	StringEscapeUtils.escapeHtml(param) + "\" from \"" +
	StringEscapeUtils.escapeHtml(oldConf.getRaw(param)) +
	"\" to default</p>");
	reconf.reconfigureProperty(param, null);
	} else if (!value.equals("default") && !value.equals("null") &&
	!value.isEmpty() &&
	(oldConf.getRaw(param) == null \|\|
	!oldConf.getRaw(param).equals(value))) {
	// change from default or value to different value
	if (oldConf.getRaw(param) == null) {
	out.println("<p>Changed \"" +
	StringEscapeUtils.escapeHtml(param) +
	"\" from default to \"" +
	StringEscapeUtils.escapeHtml(value) + "\"</p>");
	} else {
	out.println("<p>Changed \"" +
	StringEscapeUtils.escapeHtml(param) + "\" from \"" +
	StringEscapeUtils.escapeHtml(oldConf.
	getRaw(param)) +
	"\" to \"" +
	StringEscapeUtils.escapeHtml(value) + "\"</p>");
	}
	reconf.reconfigureProperty(param, value);
	} else {
	LOG.info("property " + param + " unchanged");
	}
	} else {
	// parameter value != newConf value
	out.println("<p>\"" + StringEscapeUtils.escapeHtml(param) +
	"\" not changed because value has changed from \"" +
	StringEscapeUtils.escapeHtml(value) + "\" to \"" +
	StringEscapeUtils.escapeHtml(newConf.getRaw(param)) +
	"\" since approval</p>");
	}
	}
	}
	}
	}

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
	throws ServletException, IOException {
	LOG.info("GET");
	resp.setContentType("text/html");
	PrintWriter out = resp.getWriter();

	Reconfigurable reconf = getReconfigurable(req);
	String nodeName = reconf.getClass().getCanonicalName();

	printHeader(out, nodeName);
	printConf(out, reconf);
	printFooter(out);
	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
	throws ServletException, IOException {
	LOG.info("POST");
	resp.setContentType("text/html");
	PrintWriter out = resp.getWriter();

	Reconfigurable reconf = getReconfigurable(req);
	String nodeName = reconf.getClass().getCanonicalName();

	printHeader(out, nodeName);

	try {
	applyChanges(out, reconf, req);
	} catch (ReconfigurationException e) {
	resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
	StringUtils.stringifyException(e));
	return;
	}

	out.println("<p><a href=\"" + req.getServletPath() + "\">back</a></p>");
	printFooter(out);
	}

	}