image.png

上面的拓扑图，LB1和LB2是两个Nginx反向代理，后端RS1和RS2是两个Web服务器。
接下来我们通过keepalived实现高可用的nginx反向代理集群。

keepalived的实现本质是：
当LB1和LB2都正常运行时，把VIP 172.16.80.201分配给高优先级的LB1。用户访问时，就由LB1提供反向代理。
当LB1出现故障时，keepalived就会把VIP漂移到LB2，由LB2提供反向代理功能。从而保证了业务的正常运行。

---

RS1和RS2配置

1、安装Nginx

[root@RS1 ~]#yum install nginx -y
[root@RS2 ~]#yum install nginx -y

2、配置访问页面，并启动RS1和RS2的Nginx服务

[root@RS1 ~]#vim /usr/share/nginx/html/index.html 
RS1 172.16.80.100
[root@RS2 ~]#vim /usr/share/nginx/html/index.html 
RS2 172.16.80.102

客户端访问RS1和RS2效果如下：
web页面如下：

image.png

LB1和LB2的配置

1、LB1和LB2的Nginx负载均衡配置

[root@LB1 nginx]#vim /etc/nginx/nginx.conf
worker_processes  4;
events {
    worker_connections  1024;
}
http {
    include       mime.types;
    default_type  application/octet-stream;
    server_tokens off;
    sendfile        on;
    keepalive_timeout  65;
    upstream www.server.pools {
        server 172.16.80.100:80 weight=1;
        server 172.16.80.102:80 weight=1;
    }
    server {
        listen       80;
        server_name  www.keepalived.com;
        location / {
        proxy_pass http://www.server.pools;
        proxy_set_header Host $host;
        proxy_set_header X-Forwardered-For $remote_addr;
        }

        }
}

LB2的Nginx配置与LB1一样。配置后重启nginx服务。客户端分别访问172.16.80.101和172.16.80.103，可以看到LB实现了负责均衡的反向代理：

image.png

2、LB1和LB2通过keepalived实现高可用
安装keepalived

[root@LB1 ~]#yum install keepalived ipvsadm  -y
[root@LB2 ~]#yum install keepalived ipvsadm  -y

配置VRRP实例，LB1为master，LB22为backup。
VS1配置：

[root@LB1 ~]#vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {
   notification_email {
   root@localhost
}
   notification_email_from keadmin@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id CentOS7A.luo.com
   vrrp_mcast_group4 224.0.0.22
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass haha
    }
    virtual_ipaddress {
        172.16.80.201/16
    }

}

LB2配置

[root@LB2 ~]#vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {                                            <==全局配置段开始
   notification_email {                                  
   root@localhost                                        <==故障邮件的收件人
}                                                    
   notification_email_from keadmin@localhost             <==故障邮件的发件人
   smtp_server 127.0.0.1                                 <==故障邮件的发件服务器
   smtp_connect_timeout 30
   router_id CentOS7B.luo.com                            <==路由器ID
   vrrp_mcast_group4 224.0.0.22                          <==组播地址
}                                                        <==全局配置段结束 

vrrp_instance VI_1 {                                     <==实例名字为VI_1，备节点的实例名字要和主节点的相同
    state BACKUP                                         <==状态为backup
    interface ens33                                      <==通信的接口
    virtual_router_id 51                                 <==实例ID
    priority 100                                         <==优先级
    advert_int 1                                         <==通信检查时间间隔
    authentication {
        auth_type PASS                                   <==认证类型
        auth_pass haha                                   <==认证密码
    }
    virtual_ipaddress {
        172.16.80.201/16                                 <==虚拟IP
    }
}

配置完后，启动VS1和VS2的keepalived

image.png image.png

上图可以看到，LB1成功拿到VIP 172.16.80.201。

验证

image.png

客户端访问http://172.16.80.201时，被轮询调度到RS1和RS2。
当我把LB1关机后，VIP就会被keepalived分配到LB2。这时客户端再次访问http://172.16.80.201，仍然被轮询调度到后端RS服务器，用户是无法感知到LB1的故障的。