Hi Dude, today I will write simple article about setup multiple tomcat load balancing using apache and mod JK.
Overview Simple topology configuration described by picture below.
I will create a 3 node server, with the IP address configuration below:
| Node | Hostname | IP Address | Service | jvmRoute |
|---|---|---|---|---|
| Server1 | tcserver1.habibza.in | 192.168.197.144 | Tomcat + Apache + ModJK | tcserver1 |
| Server2 | tcserver2.habibza.in | 192.168.197.145 | Tomcat | tcserver2 |
| Server3 | tcserver3.habibza.in | 192.168.197.146 | Tomcat | tcserver3 |
in my previous post, I’ve written about tomcat and apache modJK. But as of this writing, it only uses 1 tomcat node/server.
So in this post, I’m going to use multiple Servers. Ok, let’s get started.
NOTE : I will start by working on server 2 and server 3 first. Because just install tomcat only.
Install Tomcat in node 1, 2 and 3
This is my configuration in tomcat multiple setup. I prefer to setup on server 1, 2 and server 3 first. So do the same thing below on server 2 and server 3.
Set Server Hostname
hostnamectl set-hostname tcserver2.habibza.inSet Hostname in /etc/hosts
root@tcserver1:~# cat /etc/hosts
127.0.0.1 localhost
# The following lines are desirable for IPv6 capable hosts
192.168.197.144 tcserver1.habibza.in tcserver1
192.168.197.145 tcserver2.habibza.in tcserver2
192.168.197.146 tcserver3.habibza.in tcserver3
Install Tomcat using apt
root@tcserver1:~# apt update
root@tcserver1:~# apt-get install tomcat9 tomcat9-docs tomcat9-examples tomcat9-adminAfter installation fisinshed, lets check java version.
root@tcserver1:~# java -version
openjdk version "11.0.11" 2021-04-20 OpenJDK Runtime Environment (build 11.0.11+9-Ubuntu-0ubuntu2.20.04) OpenJDK 64-Bit Server VM (build 11.0.11+9-Ubuntu-0ubuntu2.20.04, mixed mode, sharing)Set Tomcat User
After that go to /etc/tomcat9/tomcat-users.xml.
<tomcat-users . . .>
<user username="admin" password="password" roles="manager-gui,admin-gui"/>
</tomcat-users>Set Tomcat Communicate with Apache via Mod JK and Pointing Worker
Open file /etc/tomcat9/server.xml. Add this line to activate AJP 1.3 protocol and set jvmroute.
root@tcserver1:~# vim /etc/tomcat9/server.xml
...
...
<engine name="Catalina" defaulthost="localhost" jvmroute="tcserver1"></engine>jvmRoute= tcserver1 on server 192.168.197.144jvmRoute= tcserver2 on server 192.168.197.145jvmRoute= tcserver3 on server 192.168.197.146
Open browser and type this url.
http://192.168.197.144:8080NOTE: Up to this stage, apply the same steps to server 2 and server 3.
After installation and tomcat setup finished. We can make sure the setup properly by type the IP in the browser.
http://192.168.197.146:8080http://192.168.197.145:8080Next, install Apache and Mod jk in server1.
It’s up to you where to install apache http and mod jk, but this time I prefer to install on server1.
root@tcserver1:~# apt install apache2 libapache2-mod-jkEnable JK Module
Let’s check, whether the mod is loaded or not.
root@tcserver:~# systemctl restart apache2.service
root@tcserver:~# apache2ctl -M | grep jk
jk_module (shared)Look bold red jk_module (shared)which means Mod JK already active. And now check port .
root@tcserver1:~# netstat -tulpn
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN 820/systemd-resolve
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 892/sshd: /usr/sbin
tcp6 0 0 :::22 :::* LISTEN 892/sshd: /usr/sbin
tcp6 0 0 ::1:<strong>8009</strong> :::* LISTEN 21651/java
tcp6 0 0 :::<strong>8080</strong> :::* LISTEN 21651/java
tcp6 0 0 :::<strong>80</strong> :::* LISTEN 21582/apache2See important port below:
8009: Port AJP Connector8080: Port Tomcat80: Port Apache22: Default SSH port
Create workers.properties
This is important part. We need to configure the Apache HTTP Server to load and initialize the JK module.
Lets create the /etc/apache2/workers.properties file. This file defines a list of Tomcat ‘workers’ to which Apache can pass requests.
root@tcserver1:~# vim /etc/apache2/workers.propertiesAnd paste the following into the file.
###
worker.list=jkstatus,lb_router
# Set LOADBALANCER
worker.lb_router.type=lb
worker.lb_router.method=Requests
worker.jkstatus.type=status
# HERE is where you decide on how many Tomcat Server's there are in the cluster
worker.lb_router.balance_workers=tcserver1,tcserver2,tcserver3
worker.lb_router.sticky_session=1
# Set Worker
worker.tcserver1.port=8009
worker.tcserver1.host=192.168.197.144
worker.tcserver1.type=ajp13
worker.tcserver1.lbfactor=1
worker.tcserver2.port=8009
worker.tcserver2.host=192.168.197.145
worker.tcserver2.type=ajp13
worker.tcserver2.lbfactor=1
worker.tcserver3.port=8009
worker.tcserver3.host=192.168.197.146
worker.tcserver3.type=ajp13
worker.tcserver3.lbfactor=1Next reference this file in the primary Apache configuration file apache2.conf.
root@tcserver:~# vim /etc/apache2/apache2.confWe add these lines at the end.
JkWorkersFile /etc/apache2/workers.properties
# Where to put jk shared memory
JkShmFile /var/log/apache2/mod_jk.shm
# Where to put jk logs
JkLogFile /var/log/apache2/mod_jk.log
# Set the jk log level [debug/error/info]
JkLogLevel info
# Select the timestamp log format
JkLogStampFormat "[ %a %b %d %H:%M:%S %Y ]"Setting which URLs to manage with Apache
The last, we have to setting which URL manage with apache. Mount Document Root with JkMount.
root@tcserver1:~# vim /etc/apache2/sites-enabled/000-default.confAdd the following line under the DocumentRoot entry. This makes it so that you can request JRS via the Apache web server.
JkMount /* lb_router
#JkMount /examples/* worker1JkMount /* worker1 : Mount everything in default document root tomcat in apache with lb_router. lb-router is name of worker that defined in workers.properties.
Restart service apache and tomcat.
root@tcserver1:~# systemctl restart apache2.service
root@tcserver1:~# systemctl restart tomcat9.serviceThat is my article about tomcat load balancing apache. May be it’s helpful, please feel free to leave a comment if you have any questions and I’ll appreciate it.
