Basic Clustering
- Till now we have 1 tomcat instance running and now we'll learn how to loadbalance multiple tomcat instances.
- For this let us have another tomcat instance configured first.
- Go to the /opt directory and copy tomcat8 to tomcat8-n2
# cp -prv tomcat8 tomcat8-n2
- Now we know that we are using some ports for tomcat say 8080, 8005, 8009
- For our additional tomcat instance we need to change the ports. If we don't then we might need to experience port conflict
- I am going to edit server.xml config file in the new node and increment the port numbers by 1
# cd /opt/tomcat8-n2/conf/
# vi server.xml
8005 -> 8006
8080 -> 8081
8443 -> 8444
8009 -> 8010
- Now you need to add your new Catalina home, base and temp directories
- First you need to change the catalina.sh script and redirect the above 3 variables to the new variables
- Edit the catalina.sh script and add the following lines
# vi /opt/tomcat-n2/bin/catalina.sh
CATALINA_BASE=$CATALINA_BASE2
CATALINA_HOME=$CATALINA_HOME2
CATALINA_TMPDIR=$CATALINA_TMPDIR2
- Now edit /etc/profile file and set our new directories
# vi /etc/profile
CATALINA_BASE2=/opt/tomcat8-n2
CATALINA_HOME2=/opt/tomcat8-n2
CATALINA_TMPDIR2=/opt/tomcat8-n2/temp
- Now we need to edit /etc/nginx/vhost.d/default.conf file to add the upstream directive to loadbalance
- Edit that file and add the following at the top of the file
upstream myTomcat {
server localhost:8080;
server localhost:8081;
}
- Now we need to change the proxy_pass
proxy_pass http://myTomcat;