说明：本实验为双节点nginx为两台apache服务器提供负载均衡，本文不是做lvs，所以realserver不是配置在keepalived.conf而是在nginx的配置文件中upstream。
此架构需考虑的问题：
1）Master没挂，则Master占有vip且nginx运行在Master上
2）Master挂了，则backup抢占vip且在backup上运行nginx服务
3）如果master服务器上的nginx服务挂了，则vip资源转移到backup服务器上
4）检测后端服务器的健康状态
Master和Backup两边都开启nginx服务，无论Master还是Backup，当其中的一个keepalived服务停止后，vip都会漂移到keepalived服务还在的节点上，如果要想使nginx服务挂了，vip也漂移到另一个节点，则必须用脚本或者在配置文件里面用shell命令来控制。
配置步骤如下
1.初始化4台测试server，该关的关了
[root@host101 ~]# vim /etc/hosts
192.168.1.200 ng-vip
192.168.1.101 ng-master
192.168.1.102 ng-slave
192.168.1.161 web1
192.168.1.162 web2 [root@host101 ~]# yum clean all
[root@host101 ~]# systemctl stop firewalld.service
[root@host101 ~]# systemctl disable firewalld.service
[root@host101 ~]# sed -i "s/SELINUX=enforcing/SELINUX=disabled/g" /etc/selinux/config
2.配置web1,web2的apache服务，两台一样的方法
[root@host161 ~]# yum -y install httpd
[root@host161 ~]# systemctl start httpd
[root@host161 ~]# systemctl enable httpd
ln -s '/usr/lib/systemd/system/httpd.service' '/etc/systemd/system/multiuser.target.wants/httpd.service'
[root@host161 ~]# cat /var/www/html/index.html
hello this lvs-web1 [root@host162 ~]# yum -y install httpd
[root@host162 ~]# systemctl start httpd
[root@host162 ~]# systemctl enable httpd
ln -s '/usr/lib/systemd/system/httpd.service' '/etc/systemd/system/multiuser.target.wants/httpd.service'
[root@host162 ~]# cat /var/www/html/index.html
hello this lvs-web2
3.通过yum安装配置nginx节点，两台一样的方法
[root@host101 ~]# vim /etc/yum.repos.d/nginx.repo
[nginx]
name=nginx repo
baseurl=http://nginx.org/packages/centos/7/x86_64/
gpgcheck=0
enabled=1
[root@host101 ~]# yum clean all
[root@host101 ~]# yum -y install nginx
[root@host101 ~]# vim /usr/share/nginx/html/index.html
<h1>Welcome to ng-master!</h1>
[root@host101 ~]# cd /etc/nginx/conf.d/
[root@host101 conf.d]# mv default.conf default.conf.1
[root@host101 ~]# vim /etc/nginx/conf.d/web.conf
upstream myapp1 {
server web1;
server web2;
} server {
listen 80; location / {
proxy_pass http://myapp1;
}
}
[root@host101 ~]# systemctl restart nginx.service [root@host102 ~]# vim /etc/yum.repos.d/nginx.repo
[nginx]
name=nginx repo
baseurl=http://nginx.org/packages/centos/7/x86_64/
gpgcheck=0
enabled=1
[root@host102 ~]# yum clean all
[root@host102 ~]# yum -y install nginx
[root@host102 ~]# vim /usr/share/nginx/html/index.html
<h1>Welcome to ng-master!</h1>
[root@host102 ~]# cd /etc/nginx/conf.d/
[root@host102 conf.d]# mv default.conf default.conf.1
[root@host102 ~]# vim /etc/nginx/conf.d/web.conf
upstream myapp1 {
server web1;
server web2;
}
server {
listen 80; location / {
proxy_pass http://myapp1;
}
}
[root@host102 ~]# systemctl restart nginx.service
4.在主nginx服务器上安装keepalived，并配置nginx服务健康检测脚本
[root@host101 conf.d]# yum -y install keepalived
[root@host101 conf.d]# cd /etc/keepalived/
[root@host101 keepalived]# cp keepalived.conf keepalived.conf.1
[root@host101 keepalived]# vim keepalived.conf
global_defs {
notification_email {
abc@mail.com
}
notification_email_from abc@mail.com
smtp_server smtp.mail.com
smtp_connect_timeout 30
router_id HA_MASTER1 #表示运行keepalived服务器的一个标识，发邮件时显示在邮件主题中的信息
}
vrrp_script chk_http_port {
script "/usr/local/keepalived/nginx.sh" ####检测nginx状态的脚本链接
interval 2
weight 2
}
vrrp_instance VI_2 { #vrrp实例
state MASTER #MASTER/BACKUP
interface eno16777736 ####HA 监测网络接口
virtual_router_id 51 #虚拟路由标识，是一个数字，同一个VRRP实例使用唯一的标识,master和backup要一样
priority 100 #用于主从模式，优先级主高于100，从低于100
advert_int 1 #主备之间的通告间隔秒数
authentication { #认证用于主从模式，mater和backup配置一样
auth_type PASS ###主备切换时的验证
auth_pass 1111 #密码
}
track_script {
chk_http_port ### 执行监控的服务
}
virtual_ipaddress { 192.168.1.200/24 dev eno16777736 label eno16777736:1 ###########虚拟ip
}
}
[root@host101 keepalived]# mkdir -p /usr/local/keepalived
[root@host101 keepalived]# vim /usr/local/keepalived/nginx.sh
#!/bin/bash
if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
killall keepalived
fi
[root@host101 keepalived]# chmod 755 /usr/local/keepalived/nginx.sh
[root@host101 keepalived]# systemctl start keepalived
[root@host101 keepalived]# ifconfig -a
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.101 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::20c:29ff:fefe:6f3 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:fe:06:f3 txqueuelen 1000 (Ethernet) eno16777736:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.200 netmask 255.255.255.0 broadcast 0.0.0.0
ether 00:0c:29:fe:06:f3 txqueuelen 1000 (Ethernet) lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
5.在备nginx服务器上安装keepalived，并配置nginx服务健康检测脚本，与主略有不同
[root@host102 conf.d]# yum -y install keepalived
[root@host102 conf.d]# cd /etc/keepalived/
[root@host102 keepalived]# cp keepalived.conf keepalived.conf.1
[root@host102 keepalived]# vim keepalived.conf
global_defs {
notification_email {
abc@mail.com
}
notification_email_from abc@mail.com
smtp_server smtp.mail.com
smtp_connect_timeout 30
router_id HA_MASTER1 #表示运行keepalived服务器的一个标识，发邮件时显示在邮件主题中的信息
}
vrrp_script chk_http_port {
script "/usr/local/keepalived/nginx.sh" ####检测nginx状态的脚本链接
interval 2
weight 2
}
vrrp_instance VI_2 { #vrrp实例
state BACKUP #MASTER/BACKUP
interface eno16777736 ####HA 监测网络接口
virtual_router_id 51 #虚拟路由标识，是一个数字，同一个VRRP实例使用唯一的标识,master和backup要一样
priority 80 #用于主从模式，优先级主高于100，从低于100
advert_int 1 #主备之间的通告间隔秒数
authentication { #认证用于主从模式，mater和backup配置一样
auth_type PASS ###主备切换时的验证
auth_pass 1111 #密码
}
track_script {
chk_http_port ### 执行监控的服务
}
virtual_ipaddress { 192.168.1.200/24 dev eno16777736 label eno16777736:1 ###########虚拟ip
}
}
[root@host102 keepalived]# mkdir -p /usr/local/keepalived
[root@host102 keepalived]# vim /usr/local/keepalived/nginx.sh
#!/bin/bash
if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
killall keepalived
fi
[root@host102 keepalived]# chmod 755 /usr/local/keepalived/nginx.sh
[root@host102 keepalived]# systemctl start keepalived
[root@host102 keepalived]# ifconfig -a
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.102 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::20c:29ff:fe87:fd0e prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:87:fd:0e txqueuelen 1000 (Ethernet) lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
6.测试：通过浏览器访问测试http://192.168.1.200/，可发现流量在web1和web2之间跳转.
6.1测试关闭主nginx节点上的keepalived服务器，发绑定的vip在主节点消失
[root@host101 keepalived]# systemctl stop keepalived.service
[root@host101 keepalived]# ifconfig -a
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.101 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::20c:29ff:fefe:6f3 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:fe:06:f3 txqueuelen 1000 (Ethernet) lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback) vip在却在备节点上出现
[root@host102 keepalived]# ifconfig -a
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.102 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::20c:29ff:fe87:fd0e prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:87:fd:0e txqueuelen 1000 (Ethernet) eno16777736:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.200 netmask 255.255.255.0 broadcast 0.0.0.0
ether 00:0c:29:87:fd:0e txqueuelen 1000 (Ethernet) lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback) 通过浏览器访问测试http://192.168.1.200/，可发现流量依然在web1和web2之间跳转。
6.2再次启动主节点的keepalived服务，发现vip又重新漂移会主节点
[root@host101 keepalived]# systemctl start keepalived.service
[root@host101 keepalived]# ifconfig -a
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.101 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::20c:29ff:fefe:6f3 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:fe:06:f3 txqueuelen 1000 (Ethernet) eno16777736:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.200 netmask 255.255.255.0 broadcast 0.0.0.0
ether 00:0c:29:fe:06:f3 txqueuelen 1000 (Ethernet)
通过浏览器访问测试http://192.168.1.200/，可发现流量依然在web1和web2之间跳转。
6.3关闭nginx主节点上的nginx服务，发现vip从主节点消失，keepalived服务关闭，vip在备节点上出现。
[root@host101 keepalived]# systemctl stop nginx.service
[root@host101 keepalived]# ifconfig -a
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.101 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::20c:29ff:fefe:6f3 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:fe:06:f3 txqueuelen 1000 (Ethernet) lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback) [root@host101 keepalived]# systemctl status keepalived
keepalived.service - LVS and VRRP High Availability Monitor
Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled)
Active: inactive (dead) 通过浏览器访问测试http://192.168.1.200/，可发现流量依然在web1和web2之间跳转。
6.4再次启动主节点的nginx和keepalived服务后，VIP又漂回主节点。
[root@host101 keepalived]# systemctl start nginx.service
[root@host101 keepalived]# systemctl start keepalived
通过浏览器访问测试http://192.168.1.200/，可发现流量依然在web1和web2之间跳转。
参考：
http://www.linuxdiyf.com/linux/12955.html
http://nginx.org/en/linux_packages.html
http://blog.csdn.net/e421083458/article/details/30086413
http://my.oschina.net/u/1458120/blog/208740