ha high availability redundancy failover

Aplicacion para proveer de Alta Disponibilidad a dos servidores, que compartiran una direccion IP. Uno sera el activo y los demás pasivos.

Fuente: https://github.com/kubernetes/kubeadm/blob/master/docs/ha-considerations.md#keepalived-configuration

• Dos o más servidores que tengan una IP en la misma subred. Funciona con IPs públicas.

sudo apt-get update && sudo apt-get install -y keepalived

En este ejemplo la IP flotante será '8.8.8.8'.

1. Crear archivo:

sudo vim /etc/keepalived/keepalived.conf

Con el siguiente contenido:

! /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
    router_id LVS_DEVEL
}
vrrp_script check_apiserver {
  script "/etc/keepalived/check_apiserver.sh"
  interval 3
  weight -2
  fall 10
  rise 2
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 101
    authentication {
        auth_type PASS
        auth_pass k8s
    }
    virtual_ipaddress {
        45.150.187.221
    }
    track_script {
        check_apiserver
    }
}

Comentarios:

  ${STATE} is MASTER for one and BACKUP for all other hosts, hence the virtual IP will initially be assigned to the MASTER.
  ${INTERFACE} is the network interface taking part in the negotiation of the virtual IP, e.g. eth0.
  ${ROUTER_ID} should be the same for all keepalived cluster hosts while unique amongst all clusters in the same subnet. Many distros pre-configure its value to 51.
  ${PRIORITY} should be higher on the control plane node than on the backups. Hence 101 and 100 respectively will suffice.
  ${AUTH_PASS} should be the same for all keepalived cluster hosts, e.g. 42
  ${APISERVER_VIP} is the virtual IP address negotiated between the keepalived cluster hosts.