Centos6.3 上实现LVS+Keepalive实现http服务的双机热备

一、初始环境部署
两台centos 6.3 均最小欢安装，初始化系统环境
主机配置 master： 192.168.0.250 24
backup： 192.168.0.249 24
vip ： 192.168.0.66 24
测试端： 192.168.0.252 24
在两台主上均以下操作，配置本地yum源
cd /etc/yum.repos.d/
mv CentOS-Base.repo CentOS-Debuginfo.repo CentOS-Vault.repo /root/
vi CentOS-Media.repo
[c6-media]
name=CentOS-$releasever - Media
baseurl=file:///mnt/
file:///media/cdrom/
file:///media/cdrecorder/
gpgcheck=0
enabled=1
mount /dev/cdrom /mnt/
安装基本编译工具，以及其他工具包

yum -y install make gcc openssl-devel
yum -y install lrzsz ipvsadm sendmail httpd
二、安装lVS 和 keepalived 软件包
查看内核是否支持lvs
modprobe -l |grep ipvs
kernel/net/netfilter/ipvs/ip_vs.ko
kernel/net/netfilter/ipvs/ip_vs_rr.ko
kernel/net/netfilter/ipvs/ip_vs_wrr.ko
kernel/net/netfilter/ipvs/ip_vs_lc.ko
kernel/net/netfilter/ipvs/ip_vs_wlc.ko
kernel/net/netfilter/ipvs/ip_vs_lblc.ko
kernel/net/netfilter/ipvs/ip_vs_lblcr.ko
kernel/net/netfilter/ipvs/ip_vs_dh.ko
kernel/net/netfilter/ipvs/ip_vs_sh.ko
kernel/net/netfilter/ipvs/ip_vs_sed.ko
kernel/net/netfilter/ipvs/ip_vs_nq.ko
kernel/net/netfilter/ipvs/ip_vs_ftp.ko
出现以上信息表示支持，kernel2.6 以后支持
在www.keepalived.org 下载keepalived-1.2.15.tar.gz
tar -zxvf keepalived-1.2.15.tar.gz
cd keepalived-1.2.15
./configure --sysconf=/etc --with-kernel-dir=/usr/src/kernels/2.6.32-279.el6.x86_64
make && make install
ln -s /usr/local/sbin/keepalived /sbin/ (将keepalived指向/sbin/)
vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {
notification_email {
18792525964@139.com （这里是发送报警邮件地址）
acassen@firewall.loc
failover@firewall.loc
sysadmin@firewall.loc
}
notification_email_from Alexandre.Cassen@firewall.loc
smtp_server 192.168.0.250（这是邮件服务器地址）
smtp_connect_timeout 30 （连接smtp服务超时时间）
router_id LVS_DEVEL
}

vrrp_instance VI_1 {
state MASTER （制定服务器角色）
interface eth0
virtual_router_id 51 （虚拟路由id，一个集群id必须一样）
priority 100 （角色优先级，数值越大优先级越高）
advert_int 1 （master与backup同步检查的时间间隔，单位秒）
authentication {
auth_type PASS （验证类型，有PASS和AH）
auth_pass 1111 （验证密钥，两台机器必须一致）
}
virtual_ipaddress {
192.168.0.66 （虚拟IP地址）
}
}

virtual_server 192.168.0.66 80 {
delay_loop 6 （运行情况检查时间间隔）
lb_algo rr （设置负载调度算法）
lb_kind DR （负载均衡机制，设置DR，还有NAT和TUN模式）
nat_mask 255.255.255.0
persistence_timeout 50
protocol TCP （设置传输协议为TCP）

real_server 192.168.0.250 80 {
weight 1 （服务器权值设置）
TCP_CHECK {
connect_timeout 3 （表示3秒无响应超市）
nb_get_retry 3 （重试次数3次）
delay_before_retry 3（重试时间间隔3秒）
}
}

real_server 192.168.0.249 80 {
weight 1
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}

}
在master主机上配置如上，在backup主机祝需要修改
state BACKUP
priority 90
vi /etc/init.d/lvsrs (编写realserver启动脚本)

#!/bin/bash
NS_VIP=192.168.0.66

/etc/rc.d/init.d/functions

case "$1" in
start)
/sbin/ifconfig lo:0 $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP up
/sbin/route add -host $SNS_VIP dev lo:0
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
syscty -p > /dev/null 2>&1
echo "RealServer Start Ok"
;;
stop)
ifconfig lo:0 down
route del $SNS_VIP >/dev/null 2>&1
echo "0" > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo "0" > /proc/sys/net/ipv4/conf/lo/arp_announce
echo "0" > /proc/sys/net/ipv4/conf/all/arp_ignore
echo "0" > /proc/sys/net/ipv4/conf/all/arp_announce
echo "RealServer Stoped"
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0

chmod 755 /etc/init.d/lvsrs
/etc/init.d/keepalived start
/etc/init.d/lvsrs start
三、测试配置正确
在master上执行
echo "This is master" > /var/www/html/index.html
service httpd start
在backup上执行
echo "This is backup" > /var/www/html/index.html
service httpd start
两台机器均关闭防火墙
service iptables stop
在测试端浏览器输入http://192.168.0.66



接着停掉master上的httpd服务
service httpd stop



我们可看到已经切换到backup服务器，检查backup的日志
tail -f /var/log/messages

Mar 12 03:35:22 backup Keepalived_healthcheckers[3123]: Removing service [192.168.0.249]:80 from VS [192.168.0.66]:80
Mar 12 03:35:22 backup Keepalived_healthcheckers[3123]: SMTP connection ERROR to [192.168.0.250]:25.
Mar 12 03:39:46 backup Keepalived_healthcheckers[3123]: TCP connection to [192.168.0.249]:80 success.
Mar 12 03:39:46 backup Keepalived_healthcheckers[3123]: Adding service [192.168.0.249]:80 to VS [192.168.0.66]:80
Mar 12 03:39:46 backup Keepalived_healthcheckers[3123]: Remote SMTP server [192.168.0.250]:25 connected.
Mar 12 03:39:46 backup Keepalived_healthcheckers[3123]: Error reading data from remote SMTP server [192.168.0.250]:25.
Mar 12 03:39:55 backup Keepalived_healthcheckers[3123]: TCP connection to [192.168.0.250]:80 failed !!!
Mar 12 03:39:55 backup Keepalived_healthcheckers[3123]: Removing service [192.168.0.250]:80 from VS [192.168.0.66]:80
Mar 12 03:39:55 backup Keepalived_healthcheckers[3123]: Remote SMTP server [192.168.0.250]:25 connected.
Mar 12 03:39:55 backup Keepalived_healthcheckers[3123]: Error reading data from remote SMTP server [192.168.0.250]:25.
注意：这里master宕机backup接管，master恢复backup依然提供服务，当backup宕机master才会接管服务！不是master恢复 服务又从backup切回master！
双机热备功能已实现，你会了吗？