Hey everyone out there in BBS land. Your old friend Max here to dump out some knowledge on you.
Imagine you’re living in a world of two systems and three IP addresses. One of the IP addresses is really importing and if the system it’s running on explodes, you want it to come back up on trusty old system number two. We can use a utility for this called keepalived.
The keepalived bits can be found on the base repository for CentOS so if all is connected and such, you can install the software by running this command:
yum -y install keepalived
Master System:
Put the following in your /etc/keepalived/keepalived.conf
Making sure to change the virtual IP and the interface name!
! Configuration File for keepalived global_defs { notification_email { alerts@localhost } notification_email_from root@localhost smtp_server localhost smtp_connect_timeout 30 router_id LVS_DEVEL } vrrp_instance VI_1 { state MASTER interface eth0 virtual_router_id 51 priority 101 advert_int 1 authentication { auth_type PASS auth_pass passwordhere } virtual_ipaddress { 10.0.0.66 } }
Backup Machine:
Put the following in your /etc/keepalived/keepalived.conf:
! Configuration File for keepalived global_defs { notification_email { alerts@localhost } notification_email_from root@localhost smtp_server localhost smtp_connect_timeout 30 router_id LVS_DEVEL } vrrp_instance VI_1 { state BACKUP interface eth0 virtual_router_id 51 priority 100 advert_int 1 authentication { auth_type PASS auth_pass password } virtual_ipaddress { 10.0.0.66 } }
Start the service and make sure it starts automatically at system start
service keepalived start && chkconfig keepalived on
You’ll be able to see the IP attached to the specified interface after running
ip addr show eth0
Enjoy
Mm.,