Configuring Keepalived

Procedure

1. Run the following command in the background to modify the /etc/keepalived/keepalived.conf file and configure Keepalived for the primary LVS node:

   vi /etc/keepalived/keepalived.conf

   ! Configuration File for keepalived
    
   global_defs {
       router_id master_node
   }
    
   local_address_group laddr_gl {
   192.168.0.157 # IP address of the primary LVS node
   }
    
   vrrp_instance VI_1 {
       state MASTER
       interface eth0
       virtual_router_id   51
       priority 100
       advert_int   1
       authentication {
           auth_type PASS
           auth_pass 123456
       }
       virtual_ipaddress {
           192.168.0.27
   }
   notify_master "/etc/keepalived/notify.sh master"
   notify_backup "/etc/keepalived/notify.sh backup"
   }
    
   Vitual IP port
   virtual_server 192.168.0.27 80 { 
       delay_loop 6
       lb_algo rr
       lb_kind FNAT
       protocol TCP
       laddr_group_name laddr_gl
   Backend server node
       real_server 192.168.0.3 80 {
           weight 1
           TCP_CHECK {
               connect_timeout 15
               connect_port 80
               nb_get_retry 5
               delay_before_retry 3
           }
       }
       real_server 192.168.0.46 80 {
           weight 1
           TCP_CHECK {
               connect_timeout 15
               connect_port 80
               nb_get_retry 5
               delay_before_retry 3
           }
       }
   }
2. Run the following command in the background to modify the /etc/keepalived/keepalived.conf file and configure Keepalived for the standby LVS node:

   vi /etc/keepalived/keepalived.conf

   ! Configuration File for keepalived
    
   global_defs {
       router_id master_node
   }
    
   local_address_group laddr_gl {
   192.168.0.234 #Local IP address
   }
    
   vrrp_instance VI_1 {
       state BACKUP
       interface eth0
       virtual_router_id   51
   priority 99 #The value must be lower than that of the primary node.
       advert_int   1
       authentication {
           auth_type PASS
           auth_pass 123456
       }
       virtual_ipaddress {
           192.168.0.27
   }
   notify_master "/etc/keepalived/notify.sh master"
   notify_backup "/etc/keepalived/notify.sh backup"
   }
    
   virtual_server 192.168.0.27 80 {
       delay_loop 6
       lb_algo rr
       lb_kind FNAT
       protocol TCP
       laddr_group_name laddr_gl
       real_server 192.168.0.3 80 {
           weight 1
           TCP_CHECK {
               connect_timeout 15
               connect_port 80
               nb_get_retry 5
               delay_before_retry 3
           }
       }
       real_server 192.168.0.46 80 {
           weight 1
           TCP_CHECK {
               connect_timeout 15
               connect_port 80
               nb_get_retry 5
               delay_before_retry 3
           }
       }
   }
   NOTE:

   Perform steps 3 to 6 on both the primary and standby LVS nodes.

3. Run the following command in the background to modify the /etc/keepalived/notify.sh file:

   vi /etc/keepalived/notify.sh

   #!/bin/bash
    
   if [ $# -eq 0 ]
   then
       echo "input master/backup"
       exit 1
   fi
    
   case $1 in
   master)
           sed -i "s/#laddr_group_name/laddr_group_name/" /etc/keepalived/keepalived.conf 2>/dev/null
           systemctl reload keepalived.service
   ;;
   backup)
           if [ `grep "#laddr_group_name" /etc/keepalived/keepalived.conf|wc -l` -eq 0 ]
           then
               sed -i "s/laddr_group_name/#laddr_group_name/" /etc/keepalived/keepalived.conf 2>/dev/null
               systemctl reload keepalived.service
           fi
   ;;
   esac

   chmod +x /etc/keepalived/notify.sh

4. Run the following command to enable keepalived:

   systemctl start keepalived

5. Check whether the configuration is modified:

   ipvsadm -Ln

   

   NOTE:

   If the number of servers returned by ipvsadm is different from the actual number, check whether the listener port allows traffic to the associated backend server.

6. Run the following command to configure automatic startup:

   systemctl enable keepalived.service