keepalived实现对mysql主从复制的主备自动切换

备注：君子性非议也，善假于物也。 温故而知新，可以为师矣。

    使用MySQL+keepalived是一种非常好的解决方案，在MySQL-HA环境中，MySQL互为主从关系，这样就保证了两台 MySQL数据的一致性，然后用keepalived实现虚拟IP，通过keepalived自带的服务监控功能来实现MySQL故障时自动切换。  

       实验环境中用两台主机搭建了一个mysql主从复制的环境，两台机器分别安装了keepalived，用一个虚IP实现mysql服务器的主备自动切换功能.

模拟环境：

VIP：192.168.1.197                     ：虚拟IP地址

Master：192.168.1.198                  ：主数据库IP地址

Slave：192.168.1.199                    ：从数据库IP地址

备注：MySQL的主从同步配置不在此文档中说明（前提：主从同步已完成）

安装步骤：

1、keepalived的安装

  Yum install -y keepalived

  Chkconfig keepalived on

 2、keepalived.conf文件的配置

Master：keepalived.conf

vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived

 

global_defs {

   notification_email {

        [e-mail]    

   }

   [e-mail]

   smtp_connect_timeout 3

   smtp_server  smtp.xishiqu.com

   router_id MySQL-ha

}

 

vrrp_script check_run {                         #声明vrrp_script 的函数check_run

   script "/root/keepalived_check_mysql.sh"     #监控MySQL的脚本

   interval 5

}

 

vrrp_sync_group VG1 {

    group {

          VI_1

    }

}

vrrp_instance VI_1 {

    state MASTER                  #指定主服务器节点为主节点，备用节点上设置需一致

    interface eth0                  #指定虚拟IP的网络接口

    virtual_router_id 88   #VRRP组名，两个节点的设置必须一样，以指明各个节点属于同一VRRP组

    priority 100                 #主节点的优先级（1-254之间），备用节点必须比主节点优先级低。

    advert_int 1                 #组播信息发送间隔，两个节点设置必须一样

    nopreempt  

    authentication {             #设置验证信息，两个节点必须一致

        auth_type PASS

        auth_pass 1111

    }

    track_script {              #调用函数代码块

        check_run

    }

    virtual_ipaddress {      #虚拟IP（对外提供MySQL服务的IP地址）

        192.168.1.197       #不能和网内其他IP地址冲突

    }

}

 

Slave：keepalived.conf

! Configuration File for keepalived

 

global_defs {

   notification_email {

        [e-mail]

   }

   [e-mail]

   smtp_connect_timeout 3

   smtp_server smtp.xishiqu.cn

   router_id MySQL-ha

}

 

vrrp_script check_run {

   script "/root/keepalived_check_mysql.sh"

   interval 5

}

 

vrrp_sync_group VG1 {

    group {

          VI_1

    }

}

 

vrrp_instance VI_1 {

    state MASTER

    interface eth1                #本地网口 按实际情况配置

    virtual_router_id 88

    priority 99

    advert_int 1

    nopreempt

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    track_script {

        check_run

    }

    virtual_ipaddress {

        192.168.1.197

    }

}

3、mysql状态检测脚本

在目录root下创建脚本keepalived_check_mysql.sh：

vim /root/keepalived_check_mysql.sh

#!/bin/bash

MYSQL=/usr/local/mysql/bin/mysql

MYSQL_HOST=localhost

MYSQL_USER=root

MYSQL_PASSWORD=123456

CHECK_TIME=3

 

#mysql  is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0

 

MYSQL_OK=1

 

function check_mysql_helth (){

    $MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status;" >/dev/null 2>&1

    if [ $? = 0 ] ;then

    MYSQL_OK=1

    else

    MYSQL_OK=0

    fi

    return $MYSQL_OK

}

while [ $CHECK_TIME -ne 0 ]

do

    let "CHECK_TIME -= 1"

    check_mysql_helth

if [ $MYSQL_OK = 1 ] ; then

    CHECK_TIME=0

    exit 0

fi

if [ $MYSQL_OK -eq 0 ] &&  [ $CHECK_TIME -eq 0 ]

then

    pkill keepalived

    exit 1

fi

sleep 1

Done

 

Chmod 755 /root/keepalived_check_mysql.sh

4、两台服务器同时启动mysql和keepalived

Service keepalived restart

Service mysqld restart

5、功能验证

 #Ip a          :通过查看虚拟IP，验证keepalived服务是否启动

 #tcpdump vrrp    :查看vrrp通读记录，进行测试

 

    由keepalived的配置文件可知，mysql关闭的话，将会执行keepalived_check_mysql.sh这一脚本。这个脚本在执行的时候，会判断mysql的状态，如果mysql关闭了，将会关闭keepalived进程，将mysqld的服务切换到从数据库。而后主数据修复，需手动切换到主数据库，再重启keepalived服务。Keepalived和nagios配合使用才能提供更好的服务。