LVS+Keepalived实现负载均衡+高可用性

一、实验环境

LVS-DR-MASTER:10.0.0.1
LVS-DR-BACKUP:10.0.0.5
LVS-DR-VIP:10.0.0.200
LVS-RS1：10.0.0.2
LVS-RS2：10.0.0.3
LVS-RS4：10.0.0.4

二、实验原理

LVS使用RD模式做负载均衡，keepalived做高可用性+资源健康检查，其中LVS的DR端配置由keepalived配置完成，无需单独编写配置脚本。

三、实验步骤

在LVS-DR-MASTER和LVS-DR-BACKUP上均安装ipvsadm和keepalived

yum install -y ipvsadm keepalived

编辑LVS-DR-MASTER上的keepalived配置文件/etc/keepalived/keepalived.conf （LVS-DR-BACKUP上的配置与MASTER上的基本一致，只需要修改两处：修改state为BACKUP，修改priority小于MASTER即可。）

vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
notification_email {
[email protected]
}
notification_email_from [email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}

#定义VIP1
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
10.0.0.200
}
}

virtual_server 10.0.0.200 80 {
delay_loop 6
lb_algo rr
lb_kind DR
nat_mask 255.255.255.0
persistence_timeout 50
protocol TCP

real_server 10.0.0.2 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}

real_server 10.0.0.3 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}

real_server 10.0.0.4 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}

分别启动MASTER和BACKUP上的keepalived程序

service keepalived start

在RealServer上编写配置文件（注意要先配置ARP忽略再配置网卡）

[[email protected] ~]# vim /etc/init.d/lvsdr_rs

#!/bin/bash

echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2">/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1">/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2">/proc/sys/net/ipv4/conf/all/arp_announce

VIP=10.0.0.200
ifconfig lo:0 down
ifconfig lo:0 $VIP broadcast $VIP netmask 255.255.255.255 up
route add -host $VIP dev lo:0

执行lvsdr_rs脚本

[[email protected] ~]# chmod +x /etc/init.d/lvsdr_rs
[[email protected] ~]# /etc/init.d/lvsdr_rs

四、测试效果

高可用性：正常情况下，VIP在MASTER上，当MASTER出现问题时，VIP会漂移到BACKUP上，如果MASTER恢复正常，VIP会重新漂移到MASTER上。

负载均衡：keepalived会定时检查资源的可用性，当资源不可用时，keepalived会自动剔除这个资源，当资源恢复可用后，keepalived会自动把资源添加回资源池。

结论：高可用性和负载均衡工作正常，OK！！！

参考资料：http://www.cnblogs.com/edisonchou/p/4281978.html

参考资料：http://bbs.linuxtone.org/thread-1077-1-1.html