Keepalived 之 双主模式+DNS轮询机制 实现高负载

一、Keepalived双主模式+DNS轮询机制作用

作用：在单主模式下，备机通常会以等待状态放着，不接受任何数据，导致所有数据请求只往主机-负载均衡发送，做成资源浪费；而双主模式，即创造两个VIP，两个VIP分别放在两台负载均衡的机器上，同时两台主机均为对方的备机，以作VIP的漂移，服务接管作用，加入DNS轮询机制，使客户端的域名分别依次解释到两个VIP上，形成两台负载均衡主机同时对外提供服务。同时也解决了单主模式下的单机性能屏颈。

二、网络拓扑图

三、两台负载均衡主机的Keepalived 配置文件

lb01 keepalived.conf

! Configuration File for keepalived

global_defs {
   notification_email {
   [e-mail]
}
   notification_email_from [e-mail]
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id lb01
}

vrrp_instance VI_1 {
    state MASTER
    interface eth1
    virtual_router_id 53
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 3333
    }
    virtual_ipaddress {
        10.3.150.200/24 dev eth1 label eth1:1
    }
}
vrrp_instance VI_2 {
    state BACKUP
    interface eth1
    virtual_router_id 54
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 4444
    }
    virtual_ipaddress {
        10.3.150.201/24 dev eth1 label eth1:1
    }
}

lb02 keepalived.conf

! Configuration File for keepalived

global_defs {
   notification_email {
   [e-mail]
}
   notification_email_from [e-mail]
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id lb01
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth1
    virtual_router_id 53
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 3333
    }
    virtual_ipaddress {
        10.3.150.200/24 dev eth1 label eth1:1
    }
}
vrrp_instance VI_2 {
    state MASTER
    interface eth1
    virtual_router_id 54
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 4444
    }
    virtual_ipaddress {
        10.3.150.201/24 dev eth1 label eth1:1
    }
}

四、两台负载均衡主机的上的nginx配置文件

worker_processes  1;
events {
    worker_connections  1024;
}
http {
    include       mime.types;
    default_type  application/octet-stream;
    sendfile        on;
    keepalive_timeout  65;
    
        server 10.3.150.198:80 weight=1;
        server 10.3.150.199:80 weight=1;
        }
    server {
        listen       80;
        server_name  localhost;
        location / {
             proxy_pass http://server_pools;
        }
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }
}

五、两台web主机，均为httpd，静态内容（内容不一致）

六、把www.kang.com分别添加两条A记录，解释IP为：10.3.150.200 与 10.3.150.201

七、从多个客户端分别访问www.kang.com 域名，同时观察两台负载均衡的nginx访问日志，看是否正常，如正常，代表DNS设置成功。

八、在两台负载均衡主机上，分别关停keepalived服务，看是否出现VIP漂移到备机上，如漂移过去，代表设置成功。