Keepalived 实现双机热备

首先有一个虚拟ip暴露给客户端,虚拟ip对应的mac地址为一台真实服务器,即用户向虚拟ip发送一个请求,该请求会被分发到真实服务器上。

现在有2台真实服务器,一台master,一台backup,master和backup上都运行着keepalived,当master挂了的时候,backup检测之后,自己成为master,且arp缓存虚拟ip对应的mac地址将变为backup的mac地址,这样请求虚拟ip的报文会被发送到backup

架构图如下:

Keepalived 实现双机热备

安装

主机:192.168.1.227

备机:192.168.1.246

虚拟ip:192.168.1.99

安装命令:

wget
tar -zxvf keepalived-1.2.13.tar.gz
cd keepalived-1.2.13
./configure --disable-fwmark --prefix=/usr/local/keepalived
make && make install

整理:

mkdir /etc/keepalived/
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
ln -s /usr/local/keepalived/sbin/keepalived /sbin/

配置:

vi /etc/keepalived/keepalived.conf

Master

! Configuration File for keepalived

global_defs {
  notification_email {
    acassen@firewall.loc
    failover@firewall.loc
    sysadmin@firewall.loc
  }
  notification_email_from Alexandre.Cassen@firewall.loc
  smtp_server 192.168.200.1
  smtp_connect_timeout 30
  router_id LVS_DEVEL
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.99
    }
}

Backup 和master一样,只要修改如下地方:

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 99 # 这里改为99,master优先级是100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.99
    }
}

管理命令:

停止
service keepalived stop
启动
service keepalived start
重启
service keepalived restart
查看状态
service keepalived status

测试

在本机上查看虚拟ip状态

ip add

Keepalived 实现双机热备

在同一网段的其他机器上查询arp缓存

arp -a

Keepalived 实现双机热备

这里的1.99对应的mac地址是1.227

停掉master的keepalived

service keepalived stop

在同一网段的其他机器上查询arp缓存

arp –a

Keepalived 实现双机热备

发现1.99的mac地址已经变为slave的mac地址

那么主备双机热备就完成了

总结:本篇文章实现的功能

1.master主机挂了,或者master 上keepalived挂了之后,可以切换到slave

2.master的网络不通的时候,可以立即切换到slave,但是如果只是master上的应用出现问题的时候,是不会主动切换的,这个要通过编写脚本来监控应用出问题,这个问题后续再讨论吧。

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