====== Сервис Keepalived ======

  * [[https://winitpro.ru/index.php/2019/09/09/keepalived-ha-balansirovka-plavayushhiy-ip-adres/|Keepalived: настройка высокой доступности и плавающих IP адресов в CentOS 7]]
  * [[https://habr.com/ru/post/524688/|Отказоустойчивый кластер с балансировкой нагрузки с помощью keepalived]]
  * [[https://youtu.be/oIczkkD-hOU|Видео урок: Доступ к приложениям в Bare-Metal Kubernetes]]


===== Установка ====

<code>
# apt install keepalived
</code>

===== Настройка VRRP ====

  * Разобраться: как ведет себя в случае link down eth1/2
  * [[https://github.com/acassen/keepalived/blob/master/doc/samples/keepalived.conf.vrrp.routes]]

<code>
nodeN# cat /etc/keepalived/keepalived.conf
</code><code>
vrrp_instance VI_1 {

#    state MASTER
#    state BACKUP

    interface eth0
#    interface br0
    virtual_router_id 1
    virtual_ipaddress {
        192.168.X.254 label eth0:1
#        192.168.X.254 label br0:1
        172.16.1.X/24 dev eth1
#        172.16.2.X/24 dev eth2
    }
#    virtual_routes {
#        0.0.0.0/0 via 172.16.1.254 dev eth1
#    }
    notify_backup "/usr/local/bin/vrrp.sh BACKUP"
    notify_master "/usr/local/bin/vrrp.sh MASTER"
}
</code><code>
nodeN# cat /usr/local/bin/vrrp.sh
</code><code>
#!/bin/sh

#echo $1 >> /tmp/vrrp.txt

case $1 in
    MASTER)
        ip route delete default
        ip route add default via 172.16.1.254

#        ip route add default via 172.16.1.254 table 101
#        ip route add default via 172.16.2.254 table 102
#        /root/select_isp.sh
    ;;
    BACKUP)
        ip route delete default
        ip route add default via 192.168.X.254
    ;;
esac
</code><code>
nodeN# chmod +x /usr/local/bin/vrrp.sh
</code>

===== Настройка балансировки нагрузки  =====

  * [[https://habr.com/ru/post/104621/|Балансировка нагрузки с LVS]]

<code>
gate# cat /etc/keepalived/keepalived.conf
</code><code>
# prod_nodes
virtual_server 172.16.1.X 1194 {
  protocol UDP
  lb_algo wlc
  lb_kind NAT
  real_server 192.168.X.201 1194 {
    weight 1
    TCP_CHECK {
        connect_port 7505
    }
  }
  real_server 192.168.X.202 1194 {
    weight 1
    TCP_CHECK {
        connect_port 7505
    }
  }
}

# test_nodes
virtual_server 172.16.1.X 2194 {
  real_server 192.168.X.203 1194 {
    TCP_CHECK {
        connect_port 7505
    }
  }
}


#virtual_server 172.16.1.X 80 {
#  protocol TCP
#  lb_algo wlc
#  lb_kind NAT

#  real_server 192.168.X.10 82 {}
#  real_server 192.168.X.10 8000 {}

#  real_server 192.168.X.10 NNNNN {TCP_CHECK {}}
#  ...

#  real_server 192.168.X.201 NNNNN {TCP_CHECK {}}
#  ...
#  real_server 192.168.X.203 NNNNN {TCP_CHECK {}}
#  ...
#  real_server 192.168.X.10 80 {}
#}
</code>

===== Запуск и мониторинг =====
<code>
# keepalived -t

# service keepalived restart

# watch "service keepalived status | cat"

# watch ipvsadm -L -n

# ipvsadm -L -n -c
</code>