Failover using VRRP Keepalived

Requirements:

• 2 Server atau lebih dalam 1 jaringan yang sama
• 1 Virtual IP (VIP)

Disini saya menggunakan 3 Server Ubuntu 16.04 dan HAProxy dibelakangnya:
`node1 = 10.0.0.5
node2 = 10.0.0.6
node3 = 10.0.0.7
VIP = 10.0.0.200`

Langsung saja berikut cara Failover menggunakan VRRP (Virtual Router Redundancy Protocol) sebagai berikut

Pasang paket Keepalived disemua node

apt install keepalived -y

Buat Konfigurasi Keepalived disemua node

vim /etc/keepalived/keepalived.conf

vrrp_script haproxy-check {
    script "killall -0 haproxy"
    interval 2
    weight 20
}
 
vrrp_instance haproxy-vip {
    state MASTER
    priority 101
    interface ens3
    virtual_router_id 51
    advert_int 3
 
    unicast_src_ip 10.0.0.5
    unicast_peer {
        10.0.0.6
        10.0.0.7
    }
 
    virtual_ipaddress {
        10.0.0.200
    }
 
    track_script {
        haproxy-check weight 20
    }

Sesuaikan bagian:
`interface` (interface yang digunakan untuk failover)
`priority` (prioritas masing-masing node)
`unicast_src_ip` (IP node tersebut)
`unicast_peer` (IP node lainnya)

Muat ulang servis Keepalived

systemctl enable keepalived
systemctl restart keepalived
systemctl status keepalived

Verifikasi disemua node:

root@node3:~# ip address 
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:52:a1:72 brd ff:ff:ff:ff:ff:ff
    inet 10.0.0.7/24 brd 10.0.0.255 scope global ens3
       valid_lft forever preferred_lft forever
    inet 10.0.0.200/32 scope global ens3
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe52:a172/64 scope link

Test Failover
~ Matikan node yang saat ini menempel VIP
~ Pantau konfigurasi IP di node lainnya dengan perintah

watch -n1 ip address

Sekian.