Setup Load-Balancing Cluster with LVS and Piranha on Centos 6

This setup guide is about building web cluster with a pair of Linux loadbalancers as frontend. It uses Linux Virtual Server(LVS) and Piranha. Piranha is a web-based gui installed in LVS Routers primarily to generating a valid /etc/lvs.cf file. Start by installing LVS on LVS Router.

[root@lvsrouter ~]# yum groupinstall "Load Balancer"
================================================================================
 Package         Arch        Version                         Repository    Size
================================================================================
Installing:
 ipvsadm         x86_64      1.25-10.el6                     base          41 k
 piranha         x86_64      0.8.6-2.el6_4.1                 updates      623 k
Installing for dependencies:
 libedit         x86_64      2.11-4.20080712cvs.1.el6        base          74 k
 libnl           x86_64      1.1-14.el6                      base         121 k
 php             x86_64      5.3.3-22.el6                    base         1.1 M
 php-cli         x86_64      5.3.3-22.el6                    base         2.2 M
 php-common      x86_64      5.3.3-22.el6                    base         524 k

Transaction Summary
================================================================================
Install       7 Package(s)

Total download size: 4.7 M
Installed size: 18 M
Is this ok [y/N]: y

Start piranha and pulse services on reboot.

chkconfig piranha-gui on
chkconfig pulse on

Set a password for piranha web

/usr/sbin/piranha-passwd

Allow ports in iptables

vi /etc/sysconfig/iptables
-A INPUT -m state --state NEW -m tcp -p tcp --dport 3636 -j ACCEPT

Edit piranha config

vi  /etc/sysconfig/ha/conf/httpd.conf

Start the piranha gui service

service piranha-gui start

For LVS router to forward network packets properly to real servers, each LVS router node must have IP forwarding turned on. Turn on packet forwarding by editing sysctl.conf:

vi /etc/sysctl.conf
net.ipv4.ip_forward = 1

Reload sysctl

sysctl -p /etc/sysctl.conf

Start http services on the Real Servers

service httpd start

On the LVS Router, log in to the Piranha web ui to begin configuration. (eg http://(loadbalancer-ip):3636). Using "piranha" as user name, and key in the newly setup password. Enter Primary Router's IP address in "Global Settings"->"Primary server public IP:".

Enter Redundant Router's IP address in "Redundancy"->"Redundant server public IP:".

Enter Virtual Server settings in "Virtual Servers"->"Virtual Server".

Include Real Server settings in "Virtual Servers"->"Real Server".

On each time the Piranha Gui was changed, have to sync the settings to Backup Routers, and restart the pulse service on both routers.

service pulse restart

To see the virtual server's statistics, use "watch ipvsadm".

[root@lvsrouter ~]# watch ipvsadm 

Create arptables entry for each Virtual IP address on each Real Server(eg Webserver). You can add below command to /etc/rc.local to start on every reboot. If the network adaptor on Real Server is eth0, refer to below, if not change as according:

ip addr add (virtual ip) dev eth0:1

Direct Routing with arptables_jf. To configure each real server to ignore ARP requests for each of the virtual IP addresses the Piranha cluster services:

yum install arptables_jf
arptables -A IN -d (virtual_ip) -j DROP
arptables -A OUT -d (virtual_ip) -j mangle --mangle-ip-s (real_ip)
chkconfig arptables_jf on
service arptables_jf save
service arptables_jf restart

Create a loopback on each Real Server for monitoring Virtual IP.

vi /etc/sysconfig/network-scripts/ifcfg-lo:0

DEVICE=lo:0
IPADDR=(Virtual IP)
NETMASK=255.255.255.255
NETWORK=192.168.0.0
ONBOOT=yes
NAME=loopback