LVS+keepalived实现双机热备

昨晚写了关于lvs的文章，今天以实例介绍下LVS+keepalived实现双机热备
服务器IP地址设置表

服务器名称	网络接口	IP地址
路由器	外网IP	121.201.24.138
lvs-master	eth0	172.16.100.2
	eth1(VIP)	172.16.100.100
lvs-backup	eth0	172.16.100.3
	lo:0(VIP)	172.16.100.100
web1	eth0	172.16.100.4
	lo:0(VIP)	172.16.100.100
web2	eth0	172.16.100.5
	lo:0(VIP)	172.16.100.100

部署两台或者多台LVS调度器,仅有一台调度器作为主服务器,其他调度器作为备用,当主调度器发生故障时,keepalived会自动将备用服务器升为主服务器

1.lvsmaster端

下载keepalived服务

yum install -y keepalived

源码安装

yum install -y openssl openssl-devel
wget http://www.keepalived.org/software/keepalived-1.2.12.tar.gz tar xvf keepalived-1.2.12.tar.gz
cd keepalived-1.2.12
./configure --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc --mandir=/usr/share
make && make install

配置keepalived

[root@lvsmaster ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
notification_email {
czwan@xxx.com
}
## 默认的配置文件中,使用第三方smtp服务器,但这在现实中几乎没有意义（需要验证的原因）,我们将其指定为localhost, 将通知信息的发送交给本地sendmail服务处理
notification_email_from root@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}

vrrp_instance VI_1 {
state MASTER         ## 从使用BACKUP
interface eth0          ## 确认对外开放的端口,这里设置错误,将导致不会建立VIP
virtual_router_id 51
priority 100            ## 从要比主低,我设置为80
advert_int 5
mcast_src_ip 172.16.100.2  ##lvs的IP,从IP为172.16.100.3
authentication {
auth_type PASS
auth_pass Golo
}

# notify_master,notify_backup和notify_fault
# 分别表示在节点变为master，节点变为backup和节点不可用时执行的脚本
notify_master "/etc/keepalived/master.sh"
notify_backup "/etc/keepalived/backup.sh"
notify_fault "/etc/keepalived/fault.sh"

## 在keepalived的配置文件最前面加入以下代码，定义一个跟踪脚本：(解决脑裂问题)
vrrp_script check_local { #定义一个名称为check_local的检查脚本
script "/usr/local/keepalived/bin/check_local.sh" #shell脚本的路径
interval 5  #运行间隔
weight -15 #优先级变化
}

## 再在vrrp_instance配置中加入以下代码使用上面定义的检测脚本：
track_script {
check_local
}

virtual_ipaddress {
172.16.100.100     ## VIP
}
}
virtual_server 172.16.100.100 80 {
delay_loop 6
lb_algo rr
lb_kind DR
persistence_timeout 60
protocol TCP

real_server 172.16.100.2 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 172.16.100.3 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}

2.lvsbackup端

lvs-backup的修改参照上面的注释部分

开启keepalived服务

/etc/init.d/keepalived start

执行ipvsadm可以看到keepalived中配置已经在ipvsadm中调用

[root@lvsmastert ~]# ipvsadm
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  172.16.100.100:http rr persistent 50
-> web1:http                    Route   3      0          0
-> web2:http                    Route   3      0          0

3.web端

web端配置于前篇lvs文章中一样,这里写成脚本形式开机自启动
在/etc/init.d/下web1 172.16.100.4和web2 172.16.100.5上的脚本lvs
内容如下：

#add for chkconfig
#chkconfig: 2345 70 30
#description: lvs's script
#processname: lvs
#!/bin/bash
VIP=172.16.100.100
source /etc/rc.d/init.d/functions
case "$1" in
start)
ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP
/sbin/route add -host $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
echo "RealServer Start OK"
;;
stop)
ifconfig lo:0 down
route del $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 "RealServerStoped"
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0

为脚本lvs添加权限,并启动

chkconfig lvs on
service lvs start

安装并启动nginx，这里不多做介绍

4.结果验证

在lvs服务器上查看系统日志,服务启动成功

[root@lvsmaster ~]# tail -f -n 100 /var/log/messages
Aug 13 16:03:25 sz-mycar-lvssla1 Keepalived_healthcheckers[20193]: IPVS: Service already exists
Aug 13 16:03:25 sz-mycar-lvssla1 Keepalived_healthcheckers[20193]: IPVS: Destination already exists
Aug 13 16:03:25 sz-mycar-lvssla1 Keepalived_healthcheckers[20193]: IPVS: Destination already exists
Aug 13 16:03:25 sz-mycar-lvssla1 Keepalived_healthcheckers[20193]: Using LinkWatch kernel netlink reflector...
Aug 13 16:03:25 sz-mycar-lvssla1 Keepalived_healthcheckers[20193]: Activating healthchecker for service [172.16.100.4]:80
Aug 13 16:03:25 sz-mycar-lvssla1 Keepalived_healthcheckers[20193]: Activating healthchecker for service [172.16.100.5]:80
Aug 13 16:03:34 sz-mycar-lvssla1 Keepalived_healthcheckers[20193]: Remote SMTP server [127.0.0.1]:25 connected.
Aug 13 16:03:34 sz-mycar-lvssla1 Keepalived_healthcheckers[20193]: SMTP alert successfully sent.

查看lvsmaster,可看到VIP在master上

[root@lvsmaster ~]# ip a li eth2
2: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:52:4f:2a:de brd ff:ff:ff:ff:ff:ff
inet 172.16.100.2/24 brd 172.16.100.255 scope global eth2
inet 172.16.100.100/32 scope global eth2
inet6 fe80::5054:52ff:fe4f:2ade/64 scope link
valid_lft forever preferred_lft forever

将lvsmaster上的keepalived服务关闭,可发现VIP已经切换到lvsbackup

[root@lvsbackup ~]# ip a li eth2
2: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:2b:55:07:d9 brd ff:ff:ff:ff:ff:ff
inet 172.16.100.3/24 brd 172.16.100.255 scope global eth2
inet 172.16.100.100/32 scope global eth2
inet6 fe80::5054:2bff:fe55:7d9/64 scope link
valid_lft forever preferred_lft forever

主从切换成功,且服务照常运行