nginx + keepalive 实现HA

一、拓扑环境：

主nginx负载均衡器 192.168.166.203

辅nginx负载均衡器 192.168.166.177

VIP地址 192.168.166.178

http://www.keepalived.org/download.html

tar -zxvf keepalived-1.2.1.tar.gz

cd keepalived-1.2.1

./configure --prefix=/usr/local/keepalived --sysconf=/etc
make && make install

cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/

cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

cp /usr/local/keepalived/sbin/keepalived /bin/

chkconfig --add keepalived

chmod 755 /etc/init.d/keepalived

chkconfig keepalived on

service keepalived start

二．修改配置文件为以下内容:　[master slave]

MASTER

vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {

xxx@xxx.com

}
notification_email_from
xxx@xxx.com

smtp_server xxx.smtp.com

smtp_connect_timeout 30

router_id LVS_DEVEL

}
vrrp_script Monitor_Nginx {

script "/root/monitor_nginx.sh"

interval 2

weight 2

}
vrrp_instance VI_1 {

state MASTER #(主机为MASTER，备用机为BACKUP)

interface eth0 #(HA监测网络接口)

virtual_router_id 61 #(主、备机的virtual_router_id必须相同)

#mcast_src_ip 192.168.166.203 #(多播的源IP，设置为本机外网IP，与VIP同一网卡)此项可不设置

priority 90 #(主、备机取不同的优先级，主机值较大，备份机值较小,值越大优先级越高)

advert_int 1 #(VRRP Multicast广播周期秒数)

authentication {

auth_type PASS #(VRRP认证方式)

auth_pass 1234 #(密码)

}

track_script {

Monitor_Nginx #(调用nginx进程检测脚本)

}

virtual_ipaddress {

192.168.166.178 #(VRRP HA虚拟地址)

}

}

###BACKUP方面只需要修改state为BACKUP , priority比MASTER稍低就OK了

三：注：monitor_nginx.sh为监控nginx进程的脚本,内容如下
#!/bin/bash

if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]

then

/usr/local/nginx/sbin/nginx

sleep 5

if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]

then

killall keepalived

fi

fi
#chmod +x monitor_nginx.sh

四.启动keepalived

service keepalived start

或

/usr/local/keepalived/sbin/keepalived -D -f /etc/keepalived/keepalived.conf

五．测试步骤
1． 访问VIP看是否能够正常访问后端的web

2． 停止其中一个web看是否能将访问转到另一台上

3． 停止两台nginx上任何一个nginx进程看监控进程脚本是否会自动启动nginx

4． 停止任何一台nginx上的keepalived进程看另一台是否接管vip

track_interface的意思是将Linux中你想监控的网络接口卡监控起来，当其中的一块出现故障是keepalived都将视为路由器出现故障。

这里请注意： virtual_router_id 61，同一组master/backup中，也就是如果你设置了多个VRRP，同一组这个ID必须相同，不然启动的时候主从都会把VIP给启动了
keepalived 通过发送和接收组播包中的同一个virtual_router_id 的中的成员的存活，来确定对方的不可用，一旦检测到对方的不可用，即会切换它的备份角色为主。

即：当真实机192.168.166.177上的keepalived 检测到 真实机192.168.166.203上的keepalived 不可用时，177上将使用vip:192.168.166.178对外服务并由backup角色转变为master

keepalived+nginx实现 HA与负载均衡中keepalived负责实现HA功能，控制VIP(虚拟网络地址)转移功能，nginx实现对realserver七层负载均衡功能，nginx提供代理服务和cache功能，DNS服务可以负责前段VIP的负载均衡。



keepalived的配置

192.168.200.1 keepalived配置

! Configuration File for keepalived

global_defs {

notification_email {

xxx@xxx.com

}

notification_email_from
xxx@xxx.com

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id LVS_TEST_YDQ

}

vrrp_instance VI_1 {

state MASTER

interface eth0

virtual_router_id 61

priority 150

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

192.168.200.101/24 dev eth0 label eth0:0

}

}

vrrp_instance VI_2 {

state BACKUP

interface eth0

virtual_router_id 62

priority 100

advert_int 1

authentication {

auth_type PASS

auth_pass 2222

}

virtual_ipaddress {

192.168.200.102/24 dev eth0 label eth0:1

}

}

vrrp_instance VI_3 {

state BACKUP

interface eth0

virtual_router_id 63

priority 50

advert_int 1

authentication {

auth_type PASS

auth_pass 3333

}

virtual_ipaddress {

192.168.200.103/24 dev eth0 label eth0:1

}

}