集群介绍

  • 根据功能划分为两大类:高可用和负载均衡
    1. 高可用集群,即“HA"集群,也常称作“双机热备”,用于关键业务。核心原理都是通过心跳线连接两台服务器,一台用于提供服务,另外一台作为冗余,当提供服务的机器宕机,冗余将接替继续提供服务,实现高可用的开源软件有:heartbeat、keepalived。
    2. 负载均衡集群,需要有一台服务器作为分发器,它负责把用户的请求分发给后端的服务器处理,在这个集群里,除了分发器外,就是给用户提供服务的服务器了,这些服务器数量至少为2台,实现负载均衡的开源软件有LVS、keepalived、haproxy、nginx,商业的有F5、Netscaler。

Keepalived介绍

  • 在这里我们使用keepalived来实现高可用集群,因为heartbeat在centos6上有一些问题,影响实验效果。
  • keepalived通过VRRP(Virtual Router Redundancy Protocl,虚拟路由冗余协议)来实现高可用。
    1. 它是实现路由高可用的一种通信协议,在这个协议里会将多台功能相同的路由器组成一个小组,这个小组里会有1个master角色和N(N>=1)个backup角色。
    2. master会通过组播的形式向各个backup发送VRRP协议的数据包,当backup收不到master发来的VRRP数据包时,就会认为master宕机了。此时就需要根据各个backup的优先级来决定谁成为新的mater。
    3. Keepalived要有三个模块,分别是core、check和vrrp。其中core模块为keepalived的核心,负责主进程的启动、维护以及全局配置文件的加载和解析,check模块负责健康检查,vrrp模块是来实现VRRP协议的。

用Keepalived配置高可用集群

生产环境中,很多企业把Nginx作为负载均衡器来用,它的重要性很高,一旦宕机会导致整个站点不能访问,所以有必要再准备一台备用Nginx,Keepalived用在这种场景下非常合适。

1.准备工作
  • 准备两台机器100和110,100作为master,110作为backup。
  • 定义一个VIP:172.16.111.150

    VIP的英文名字是“Virtual IP",即“虚拟IP",也有人把它叫作“浮动IP”,因为这个IP是由Keepalived给服务器配置上的,服务器靠这个VIP对外提供服务,当master机器宕机,VIP被分配到backup上,这样用户看来是无感知的。

  • 两台机器都执行yum install -y keepalived
  • 两台机器都安装nginx,其中100上已经使用源码包编译安装过nginx,110上需要yum安装nginx,命令yum install -y nginx
  1. 直接通过 yum install nginx 肯定是不行的,因为yum没有nginx,所以首先把 nginx 的源加入 yum 中。
  2. 将nginx放到yum repro库中
rpm -ivh http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm
  1. 使用yum安装ngnix yum install nginx
  2. 查看nginx信息 yum info nginx
  3. 启动nginx service nginx start
  4. 查看nginx版本 nginx -v
2.编辑master机器的keepalived配置文件
[root@gary-tao ~]# ls /etc/keepalived/keepalived.conf 
/etc/keepalived/keepalived.conf
[root@gary-tao ~]# vi /etc/keepalived/keepalived.conf
[root@gary-tao ~]# > !$         //清空配置文件内容
[root@gary-tao ~]# viM /etc/keepalived/keepalived.conf

增加如下配置内容,按需求更改部分配置:

global_defs {                   //全局定义参数
   notification_email {
     aming@aminglinux.com          //定义接收告警的人
   }
   notification_email_from root@aminglinux.com  //定义发邮件地址(实际上没用)
   smtp_server 127.0.0.1  //定义发邮件地址,若为127.0.0.1则使用本机自带邮件服务器发送
   smtp_connect_timeout 30
   router_id LVS_DEVEL
}
vrrp_script chk_nginx {      //chk_nginx为自定义名字,后面还会用到它
    script "/usr/local/sbin/check_ng.sh"  //自定义脚本,该脚本为监控nginx服务的脚本
    interval 3   //每隔3S执行一次该脚本
}
vrrp_instance VI_1 {
    state MASTER         //角色为master
    interface ens33        //针对哪个网卡监听VIP
    virtual_router_id 51
    priority 100            //权重为100,master要比backup大
    advert_int 1   
    authentication {                        
        auth_type PASS
        auth_pass aminglinux>com       //定义密码,这个密码自定义
    }
    virtual_ipaddress {
        172.16.111.150    //定义VIP
    }
    track_script {
        chk_nginx     //定义监控脚本,这里和上面vrr_script后面的字符串保持一致
    }
}
3.编辑master机器的监控脚本
[root@gary-tao ~]# vim /usr/local/sbin/check_ng.sh  
//脚本名字是自定义的,与keepalived配置文件要一致

编辑脚本增加如下内容:

#!/bin/bash
#时间变量,用于记录日志
d=`date --date today +%Y%m%d_%H:%M:%S`
#计算nginx进程数量
n=`ps -C nginx --no-heading|wc -l`
#如果进程为0,则启动nginx,并且再次检测nginx进程数量,
#如果还为0,说明nginx无法启动,此时需要关闭keepalived
if [ $n -eq "0" ]; then
        /etc/init.d/nginx start
        n2=`ps -C nginx --no-heading|wc -l`
        if [ $n2 -eq "0"  ]; then
                echo "$d nginx down,keepalived will stop" >> /var/log/check_ng.log
                systemctl stop keepalived
        fi
fi

[root@gary-tao ~]# chmod 755 /usr/local/sbin/check_ng.sh  
//需要给它权限,否则无法被keepalived调用加载
[root@gary-tao ~]# systemctl start keepalived 
//启动master上的keepalived,如果nginx服务没有启动,它会自动拉起来,并监听VIP
[root@gary-tao ~]# ip addr  
//master上已经自动配置了172.16.111.159这个IP
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:09:e5:58 brd ff:ff:ff:ff:ff:ff
    inet 172.16.111.100/16 brd 172.16.255.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet 172.16.111.150/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::1ffb:cde1:5f3e:5778/64 scope link 
       valid_lft forever preferred_lft forever
3: ens37: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:09:e5:62 brd ff:ff:ff:ff:ff:ff
    inet 172.16.111.131/24 brd 172.16.111.255 scope global dynamic ens37
       valid_lft 1057sec preferred_lft 1057sec
    inet6 fe80::888c:a1d7:871b:8971/64 scope link 
       valid_lft forever preferred_lft forever

[root@gary-tao ~]# ps aux |grep keep
root       9467  0.0  0.1 120720  1400 ?        Ss   19:24   0:00 /usr/sbin/keepalived -D
root       9468  0.0  0.3 122792  3104 ?        S    19:24   0:00 /usr/sbin/keepalived -D
root       9469  0.0  0.2 127116  2836 ?        S    19:24   0:00 /usr/sbin/keepalived -D
root       9641  0.0  0.0 112680   976 pts/0    R+   19:26   0:00 grep --color=auto keep
[root@gary-tao ~]# ps aux |grep nginx
root       3132  0.0  0.2  46860  2892 ?        Ss   1月23   0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
nobody     6471  0.0  0.4  48784  4172 ?        S    00:00   0:00 nginx: worker process
nobody     6472  0.0  0.4  48784  4172 ?        S    00:00   0:00 nginx: worker process
root       9655  0.0  0.0 112680   976 pts/0    R+   19:26   0:00 grep --color=auto nginx
[root@gary-tao ~]# less /var/log/messages
//查看日志
4.两台机器都查看防火墙及SElinux是否开启,开启需要关闭
[root@gary-tao ~]# setenforce 0  //临时关闭SELinux

//开机关闭SELinux
编辑/etc/selinux/config文件,将SELINUX的值设置为disabled

[root@gary-tao ~]# getenforce  //查看SElinux是否关闭
Disabled
[root@gary-tao ~]# systemctl stop firewalld.service  //关闭防火墙
[root@gary-tao ~]# iptables -nvL  //查看防火墙
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination  
5.编辑backup的Keepalived配置文件
[root@gary ~]# ls /etc/keepalived/keepalived.conf 
/etc/keepalived/keepalived.conf
[root@gary ~]# > !$    //清空配置
> /etc/keepalived/keepalived.conf
[root@gary ~]# vim /etc/keepalived/keepalived.conf

编辑增加如下配置内容:

global_defs {
   notification_email {
     aming@aminglinux.com
   }
   notification_email_from root@aminglinux.com
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
}
vrrp_script chk_nginx {
    script "/usr/local/sbin/check_ng.sh"  //检测脚本
    interval 3
}
vrrp_instance VI_1 {
    state BACKUP      //这个需要改,说明是从的状态
    interface ens33
    virtual_router_id 51
    priority 90      //这个权重比master少
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass aminglinux>com
    }
    virtual_ipaddress {
        172.16.111.150   //这个跟master一样
    }
    track_script {
        chk_nginx
    }
}
6.编辑backup机器的监控脚本
[root@gary ~]# vim /usr/local/sbin/check_ng.sh

编辑增加如下配置内容:

#时间变量,用于记录日志
d=`date --date today +%Y%m%d_%H:%M:%S`
#计算nginx进程数量
n=`ps -C nginx --no-heading|wc -l`
#如果进程为0,则启动nginx,并且再次检测nginx进程数量,
#如果还为0,说明nginx无法启动,此时需要关闭keepalived
if [ $n -eq "0" ]; then
        systemctl start nginx
        n2=`ps -C nginx --no-heading|wc -l`
        if [ $n2 -eq "0"  ]; then
                echo "$d nginx down,keepalived will stop" >> /var/log/check_ng.log
                systemctl stop keepalived
        fi
fi

[root@gary ~]# chmod 755 /usr/local/sbin/check_ng.sh  //更改权限
[root@gary ~]# systemctl start keepalived  //启动服务 
[root@gary ~]# ps aux |grep keep
root      16039  0.0  0.1 120720  1400 ?        Rs   19:51   0:00 /usr/sbin/keepalived -D
root      16040  0.0  0.3 122792  3104 ?        S    19:51   0:00 /usr/sbin/keepalived -D
root      16041  0.1  0.2 127116  2656 ?        S    19:51   0:00 /usr/sbin/keepalived -D
root      16059  0.0  0.0 112676   976 pts/0    S+   19:51   0:00 grep --color=auto keep
[root@gary ~]# ps aux |grep nginx
root      15771  0.0  0.0  46308   948 ?        Ss   16:56   0:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
nginx     15772  0.0  0.2  46692  2148 ?        S    16:56   0:00 nginx: worker process
root      16077  0.0  0.0 112676   972 pts/0    S+   19:51   0:00 grep --color=auto nginx
7.测试高可用
  • 确定好两台机器上nginx差异,通过curl -I 来查看nginx版本
##master机器
[root@gary-tao ~]# curl -I 172.16.111.100
HTTP/1.1 200 OK
Server: nginx/1.12.1
Date: Fri, 26 Jan 2018 05:52:53 GMT
Content-Type: text/html
Content-Length: 26
Last-Modified: Wed, 03 Jan 2018 11:33:54 GMT
Connection: keep-alive
ETag: "5a4cbfa2-1a"
Accept-Ranges: bytes

##backup机器
[root@gary ~]# curl -I 172.16.111.110
HTTP/1.1 200 OK
Server: nginx/1.12.2
Date: Fri, 26 Jan 2018 05:54:39 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 17 Oct 2017 13:25:49 GMT
Connection: keep-alive
ETag: "59e604dd-264"
Accept-Ranges: bytes
  • 测试1:关闭master上的nginx服务

[root@gary-tao ~]# ps aux |grep nginx
root       9975  0.0  0.2  46852  2956 ?        Ss   1月25   0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
root      15423  0.0  0.0 112680   976 pts/1    R+   14:11   0:00 grep --color=auto nginx
nobody    43196  0.0  0.4  48776  4700 ?        S    00:10   0:00 nginx: worker process
nobody    43197  0.0  0.4  48776  4704 ?        S    00:10   0:00 nginx: worker process
[root@gary-tao ~]# /etc/init.d/nginx stop //关闭服务
Stopping nginx (via systemctl):                            [  确定  ]
[root@gary-tao ~]# ps aux |grep nginx  //服务自动起来
root      15492  0.0  0.1  45992  1300 ?        Ss   14:11   0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
nobody    15496  0.0  0.3  48480  3948 ?        S    14:11   0:00 nginx: worker process
nobody    15497  0.0  0.3  48480  3948 ?        S    14:11   0:00 nginx: worker process
root      15511  0.0  0.0 112680   972 pts/1    R+   14:11   0:00 grep --color=auto nginx
  • 测试2:在master上增加iptabls规则限制vrrp发包
[root@gary-tao ~]# iptables -I OUTPUT -p vrrp -j DROP 
//把主上VRRP协议出去的包封掉
[root@gary-tao ~]# iptables -nvL //查看防火墙
Chain INPUT (policy ACCEPT 22 packets, 1608 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 15 packets, 1428 bytes)
 pkts bytes target     prot opt in     out     source               destination         
   19   760 DROP       112  --  *      *       0.0.0.0/0            0.0.0.0/0        

在backup上查看
[root@gary ~]# ip add  
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:2c:5f:75 brd ff:ff:ff:ff:ff:ff
    inet 172.16.111.110/16 brd 172.16.255.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet 172.16.111.150/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::b6dc:6aed:f1d0:2f43/64 scope link 
       valid_lft forever preferred_lft forever
[root@gary ~]# tail /var/log/messages  //查看日志
Jan 26 14:16:15 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:16:15 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:16:20 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:16:20 gary Keepalived_vrrp[2837]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 172.16.111.150
Jan 26 14:16:20 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:16:20 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:16:20 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:16:20 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:20:01 gary systemd: Started Session 33 of user root.
Jan 26 14:20:01 gary systemd: Starting Session 33 of user root.

浏览器地址查看:

集群介绍、keepalived介绍、用Keepalived配置高可用集群

[root@gary-tao ~]# iptables -F  //在master恢复防火墙

//然后backup上查看ip及日志

[root@gary ~]# ip add
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:2c:5f:75 brd ff:ff:ff:ff:ff:ff
    inet 172.16.111.110/16 brd 172.16.255.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::b6dc:6aed:f1d0:2f43/64 scope link 
       valid_lft forever preferred_lft forever
[root@gary ~]# tail /var/log/messages
Jan 26 14:16:20 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:16:20 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:16:20 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:20:01 gary systemd: Started Session 33 of user root.
Jan 26 14:20:01 gary systemd: Starting Session 33 of user root.
Jan 26 14:30:01 gary systemd: Started Session 34 of user root.
Jan 26 14:30:01 gary systemd: Starting Session 34 of user root.
Jan 26 14:35:28 gary Keepalived_vrrp[2837]: VRRP_Instance(VI_1) Received advert with higher priority 100, ours 90
Jan 26 14:35:28 gary Keepalived_vrrp[2837]: VRRP_Instance(VI_1) Entering BACKUP STATE
Jan 26 14:35:28 gary Keepalived_vrrp[2837]: VRRP_Instance(VI_1) removing protocol VIPs.

浏览器地址查看:

集群介绍、keepalived介绍、用Keepalived配置高可用集群

  • 测试3:关闭master上的keepalived服务
//关闭master上的keepalived服务
[root@gary-tao ~]# systemctl stop keepalived
[root@gary-tao ~]# ip add
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:09:e5:58 brd ff:ff:ff:ff:ff:ff
    inet 172.16.111.100/16 brd 172.16.255.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::1ffb:cde1:5f3e:5778/64 scope link 
       valid_lft forever preferred_lft forever
3: ens37: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:09:e5:62 brd ff:ff:ff:ff:ff:ff
    inet 172.16.111.131/24 brd 172.16.111.255 scope global dynamic ens37
       valid_lft 1345sec preferred_lft 1345sec
    inet6 fe80::888c:a1d7:871b:8971/64 scope link 
       valid_lft forever preferred_lft forever
[root@gary-tao ~]# ps aux |grep keep
root      20375  0.0  0.0 112680   976 pts/1    R+   14:51   0:00 grep --color=auto keep
[root@gary ~]# ip addr  //在backup上VIP马上就起来了
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:2c:5f:75 brd ff:ff:ff:ff:ff:ff
    inet 172.16.111.110/16 brd 172.16.255.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet 172.16.111.150/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::b6dc:6aed:f1d0:2f43/64 scope link 
       valid_lft forever preferred_lft forever
[root@gary ~]# tail /var/log/messages
Jan 26 14:51:01 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:01 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:01 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:01 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150

浏览器地址示例图也改变:

集群介绍、keepalived介绍、用Keepalived配置高可用集群

  • 测试4:启动master上的keepalived服务
//启动master上的keepalived服务
[root@gary-tao ~]# systemctl start keepalived
[root@gary-tao ~]# ip add
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:09:e5:58 brd ff:ff:ff:ff:ff:ff
    inet 172.16.111.100/16 brd 172.16.255.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet 172.16.111.150/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::1ffb:cde1:5f3e:5778/64 scope link 
       valid_lft forever preferred_lft forever
3: ens37: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:09:e5:62 brd ff:ff:ff:ff:ff:ff
    inet 172.16.111.131/24 brd 172.16.111.255 scope global dynamic ens37
       valid_lft 1084sec preferred_lft 1084sec
    inet6 fe80::888c:a1d7:871b:8971/64 scope link 
       valid_lft forever preferred_lft forever
[root@gary-tao ~]# ps aux |grep keep
root      20384  0.0  0.1 120720  1400 ?        Ss   14:54   0:00 /usr/sbin/keepalived -D
root      20385  0.0  0.3 122792  3100 ?        S    14:54   0:00 /usr/sbin/keepalived -D
root      20386  0.0  0.2 127116  2836 ?        S    14:54   0:00 /usr/sbin/keepalived -D
root      20456  0.0  0.0 112680   976 pts/1    R+   14:55   0:00 grep --color=auto keep

[root@gary ~]# ip addr  //在backup上VIP马上断掉了
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:2c:5f:75 brd ff:ff:ff:ff:ff:ff
    inet 172.16.111.110/16 brd 172.16.255.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::b6dc:6aed:f1d0:2f43/64 scope link 
       valid_lft forever preferred_lft forever
[root@gary ~]# tail /var/log/messages  //查看日志显示
Jan 26 14:51:01 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:51:06 gary Keepalived_vrrp[2837]: Sending gratuitous ARP on ens33 for 172.16.111.150
Jan 26 14:55:12 gary Keepalived_vrrp[2837]: VRRP_Instance(VI_1) Received advert with higher priority 100, ours 90
Jan 26 14:55:12 gary Keepalived_vrrp[2837]: VRRP_Instance(VI_1) Entering BACKUP STATE
Jan 26 14:55:12 gary Keepalived_vrrp[2837]: VRRP_Instance(VI_1) removing protocol VIPs.
[root@gary ~]# 

浏览器地址示例图也改变:

集群介绍、keepalived介绍、用Keepalived配置高可用集群