Thursday, June 26, 2014

Virtual Ip With Keepalived as Front end for HAproxy server's

Install Keepalived
Virtual Ip 192.168.216.100

HAproxy Ip 192.168.216.101
1. Install Keepalived package:

On RHEL/CentOS:

$ yum install -y centos-release
$ yum install -y keepalived
$ chkconfig keepalived on

2. Tell kernel to allow binding non-local IP into the hosts and apply the changes:

$ echo "net.ipv4.ip_nonlocal_bind = 1" >> /etc/sysctl.conf
$ sysctl -p

Configure Keepalived and Virtual IP
1. Login into LB1 and add following line into /etc/keepalived/keepalived.conf:

vrrp_script chk_haproxy {
script "killall -0 haproxy" # verify the pid existance
interval 2 # check every 2 seconds
weight 2 # add 2 points of prio if OK
}

vrrp_instance VI_1 {
interface eth2 # interface to monitor
state MASTER
virtual_router_id 51 # Assign one ID for this route
priority 101 # 101 on master, 100 on backup
virtual_ipaddress {
192.168.216.100 # the virtual IP
}
track_script {
chk_haproxy
}
}
2. Login into LB2 and add following line into /etc/keepalived/keepalived.conf:

vrrp_script chk_haproxy {
script "killall -0 haproxy" # verify the pid existance
interval 2 # check every 2 seconds
weight 2 # add 2 points of prio if OK
}

vrrp_instance VI_1 {
interface eth2 # interface to monitor
state MASTER
virtual_router_id 51 # Assign one ID for this route
priority 100 # 101 on master, 100 on backup
virtual_ipaddress {
192.168.216.100 # the virtual IP
}
track_script {
chk_haproxy
}
}
3. Start Keepalived in both nodes:

$ sudo /etc/init.d/keepalived start
4. Verify the Keepalived status. LB1 should hold the VIP and the MASTER state while LB2 should run as BACKUP state without VIP:

LB1 IP:

$ ip a | grep -e inet.*eth2
inet 192.168.216.101/24 brd 192.168.216.255 scope global eth2
inet 192.168.216.100/32 scope global eth2

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