apache+mod_jk+tomcat_cluster

Apache + Mod_JK + Tomcat_cluster

 

objective:

      load_balancing the jsp and servlet , session replication

 

Servers:

   Suppose there are three servers, one is for apache and mod_JK, two of left run tomcat instance.

 

      Apache server + mod_JK   192.168.0.1/24

      Tomcat server:           192.168.0.2/3  255.255.255.0

 

Install procedure:

1.       Install apache on 192.168.0.1 as usual. Do not forget to enable DSO support. Please refer to

2.       Install Tomcat cluster on 192.168.0.2/3. Keep in mind that you have already set up JDK properly. Installation of tomcat is pretty easy,please refer to . After installation completed successfully, modify configuration relating cluster and Engine as following to server.xml – main conf file of tomcat.

 

      jvmRoute="worker73">   

     

                 channelSendOptions="8">

 

         

                   expireSessionsOnShutdown="false"

                   notifyListenersOnReplication="true"/>

 

         

           

                        address="228.0.0.4"

                        port="45564"

                        frequency="500"

                        dropTime="3000"/>

           

                      address="192.168.0.2"

                      port="4000"

                      autoBind="100"

                      selectorTimeout="5000"

                      maxThreads="6"/>

 

           

             

           

           

           

           

         

 

         

                 filter=".*\.gif;.*\.js;.*\.jpg;.*\.png;.*\.htm;.*\.html;.*\.css;.*\.txt;"/>

         

 

         

                    tempDir="/tmp/war-temp/"

                    deployDir="/tmp/war-deploy/"

                    watchDir="/tmp/war-listen/"

                    watchEnabled="false"/>

 

         

         

       

 

    Note that JvmRoute should be unique in the tomcat cluster,which identify the tomcat instance by mod_jk load balancing the requests , the address attribute of receiver in channel is the  ip address of local network interface, which receiver the info of  nodes.

 

   Install the other tomcat server as above.

 

3.       Enable Multicast to the NIC on which the receiver is configured.

a)       check whether the multicast is enabled on the given NIC of two Tomcat server

shell>ifconfig –a

eth1       Link encap:Ethernet  HWaddr 00:0F:20:32:4F:24 

          inet addr:192.168.0.2  Bcast:192.168.0.255  Mask:255.255.255.0

          inet6 addr: fe80::20f:20ff:fe32:4f24/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:1655417 errors:0 dropped:0 overruns:0 frame:0

          TX packets:2487796 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:1190134639 (1.1 GiB)  TX bytes:236306869 (225.3 MiB)

          Interrupt:201

If there is no such word “MULTICAST”, unfortunately, you have to update you OS kernel to support it, fortunately, most of OS support multicast by default.

b)      Adding an multicast route info to the given NIC

Shell> route add -net 224.0.0.0 netmask 240.0.0.0.dev eth1

c)       Here is java routine to test whether multicast works well:

Shell>  cat MulticastNode.java

import java.io.*;

import java.net.*;

 

public class MulticastNode {

        InetAddress group = null;

        MulticastSocket s = null;

 

        public static void main(String[] args){

                if (args.length > 0){

                        System.out.println("sending message: " + args[0]);

                        MulticastNode node = new MulticastNode();

                        node.send(args[0]);

                        node.receive();

                }

                else{

                        System.out.println("Need an argument string to send.");

                        System.exit(1);

                }

        }

 

        public MulticastNode() {

                try{

                        group = InetAddress.getByName("224.0.0.1");

                        s = new MulticastSocket(12345);

                        s.joinGroup(group);

                }

                catch (Exception e) {

                        e.printStackTrace();

                }

        }

 

        public void send(String msg) {

                try{

                        DatagramPacket hi = new DatagramPacket(msg.getBytes(),msg.length(),group,12345);

                        s.send(hi);

                }

                catch (Exception e){

                        e.printStackTrace();

                }

        }

 

        public void receive() {

                byte[] buf;

                while (true) {

                        try{

                                buf = new byte[1000];

                                DatagramPacket recv = new DatagramPacket(buf,buf.length);

                                s.receive(recv);

                                System.out.println("Received: " + new String(buf));

                        }

                        catch (Exception e){

                                e.printStackTrace();

                        }

                }

        }

}

  

   After compile it with javac, running it on the first server as following:

Shell> java MulticastNode node1

 then start it on the another server as below:

Shell> java MulticastNode node2

 Back to the first server, if  you see : Received node2

 Then congratulations to you

 

4. Install Mod_JK

  Install it according to the manual. Then configure it as following:

  Shell> cat mod_jk.conf

JkWorkersFile /usr/local/apache/conf/workers.properties

 

# Where to put jk logs

JkShmFile     /usr/local/apache/jklogs/live/mod_jk.shm

JkLogFile     /usr/local/apache/jklogs/live/mod_jk.log

 

# Set the jk log level [debug/error/info]

JkLogLevel info

 

# Select the log format

JkLogStampFormat "[%a %b %d %H:%M:%S %Y]"

 

# JkOptions indicate to send SSL KEY SIZE,

JkOptions  +ForwardKeySize +ForwardURICompat -ForwardDirectories

 

# JkRequestLogFormat set the request format

JkRequestLogFormat "%w %V %T"

 

#JkMount /*  loadbalancer

#JkMount /servlet/*  loadbalancer

JkMount /*.jsp loadbalancer

JkMount /*.action loadbalancer

JkMount /*.do loadbalancer

JkMount /manager/* loadbalancer

JkMount /jkmanager/* jkstatus

 

  Shell> cat workers.properties

# Defining a worker named worker72 and of type ajp13

worker.list=loadbalancer

 

# Set properties for worker73

worker.worker73.type=ajp13 

worker.worker73.host=192.168.0.2

worker.worker73.port=8009

worker.worker73.lbfactor=50 

 

# Set properties for worker74

worker.worker74.type=ajp13 

worker.worker74.host=192.168.0.3

worker.worker74.port=8009

worker.worker74.lbfactor=50 

 

worker.loadbalancer.type=lb

worker.loadbalancer.balanced_workers=worker73,worker74

worker.loadbalancer.sticky_session=True

 

 

#

# Define a status worker

#

worker.list=jkstatus

worker.jkstatus.type=status

worker.jkstatus.read_only=true

 

5. start tomcat first , then start apache.