Keepalived搭建LVS高可用集群

Keepalived可以配合LVS使用，解决LVS单点失败和后端服务器健康性检测的问题。

环境准备

客户端

eth0: 仅主机 192.168.10.6/24 GW:192.168.10.200

路由器

eth0: NAT 10.0.0.200/24
eth1: 仅主机 192.168.10.200/24
启用 IP_FORWARD

两台LVS+Keepalived

Master eth0: 10.0.0.8 vip: 10.0.0.10/32
Backup eth0: 10.0.0.18

两台后端服务器

RS1 eth0: 10.0.0.7
RS2 eth0: 10.0.0.17

服务配置

LVS-Master

安装keepalived

yum -y install keepalived

备份配置文件

cp /etc/keepalived/keepalived.conf{,.bak} 

编辑配置文件

vim /etc/keepalived/keepalived.conf

keepalived.conf

默认组播IP：224.0.0.18

! Configuration File for keepalived
​
global_defs {
   notification_email {
     root@localhost
   }   
   notification_email_from keepalived@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id ka1 
   vrrp_skip_check_adv_addr
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}
​
vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 88
    priority 100 
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }   
    virtual_ipaddress {
        10.0.0.10 dev eth0 label eth0:0
    }   
}
​
virtual_server 10.0.0.10 80 {
  delay_loop 3
  lb_algo rr
  lb_kind DR
  protocol TCP 
  real_server 10.0.0.7 80 {
    weight 1
    HTTP_GET { 
      url {
        path /
        status_code 200 
      }   
  connect_timeout 1
  nb_get_retry 3
  delay_before_retry 1
}
}
  real_server 10.0.0.17 80 {
    weight 1
    TCP_CHECK {
      connect_timeout 5
      nb_get_retry 3
      delay_before_retry 3
      connect_port 80
}
}
}

重启keepalived服务

systemctl restart keepalived

查看LVS规则是否已经自动生成

ipvsadm -Ln

LVS-Backup

安装keeplived方法同上

/etc/keepalived/keepalived.conf

global_defs {
   notification_email {
    root@localhost
   }   
   notification_email_from keepalived@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id ka2
   vrrp_skip_check_adv_addr
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}
​
vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 88
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }   
    virtual_ipaddress {
        10.0.0.10 dev eth0 label eth0:0
    }   
}
virtual_server 10.0.0.10 80 {
  delay_loop 3
  lb_algo rr
  lb_kind DR
  protocol TCP 
  real_server 10.0.0.7 80 {
    weight 1
    HTTP_GET { 
      url {
        path /
        status_code 200 
      }   
  connect_timeout 1
  nb_get_retry 3
  delay_before_retry 1
}
}
  real_server 10.0.0.17 80 {
    weight 1
    TCP_CHECK {
      connect_timeout 5
      nb_get_retry 3
      delay_before_retry 3
      connect_port 80
}
}
}

重启keepalived服务

systemctl restart keepalived

查看LVS规则是否已经自动生成

ipvsadm -Ln

后端RS1

使用脚本绑定VIP至web服务器lo网卡

lvs_dr_rs.sh

#!/bin/bash
#Author: qinwa
vip=10.0.0.10
mask=255.255.255.255
dev=lo:1
case $1 in
start)
echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce
ifconfig $dev $vip netmask $mask
echo "The RS Server is Ready!"
;;
stop)
ifconfig $dev down
echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce
echo "The RS Server is Canceled!"
;;
*)
echo "Usage: $(basename $0) start|stop"
exit 1
;;
esac

启动脚本

bash lvs_dr_rs.sh start

配置httpd

yum -y install httpd
echo rs1 10.0.0.7 >/var/www/html/index.html 
systemctl start httpd

后端RS2

使用脚本绑定VIP至web服务器lo网卡

lvs_dr_rs.sh

#!/bin/bash
#Author: qinwa
vip=10.0.0.10
mask=255.255.255.255
dev=lo:1
case $1 in
start)
echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce
ifconfig $dev $vip netmask $mask
echo "The RS Server is Ready!"
;;
stop)
ifconfig $dev down
echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce
echo "The RS Server is Canceled!"
;;
*)
echo "Usage: $(basename $0) start|stop"
exit 1
;;
esac

启动脚本

bash lvs_dr_rs.sh start

配置httpd

yum -y install httpd
echo rs1 10.0.0.17 >/var/www/html/index.html 
systemctl start httpd

访问测试

在LVS的Master节点用 ip -a 可以看到VIP是飘在主节点上的（因为它的优先级高）

在客户端访问VIP看到也是正常轮询的

在路由器抓包观察，可以看到主节点在发通告，宣告自己的优先级

tcpdump -i eth0 -nn host 224.0.0.18

这个时候把主节点（10.0.0.8）的keepalived服务停止，可以看到从节点把VIP抢过来了

再访问VIP，可以看到即使挂掉一台LVS网页还是能正常访问的，这样就实现了高可用了。