keepalived实现对mysql主从复制的主备自动切换
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 keepalivedChkconfig keepalived on 2、keepalived.conf文件的配置Master：keepalived.confvi /etc/keepalived/keepalived.conf! Configuration File for keepalivedglobal_defs { notification_email { 2729705372@qq.com } notification_email_from2729705372@qq.com smtp_connect_timeout 3 smtp_serversmtp.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 { 2729705372@qq.com } notification_email_from2729705372@qq.com 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/bashMYSQL=/usr/local/mysql/bin/mysqlMYSQL_HOST=localhostMYSQL_USER=rootMYSQL_PASSWORD=123456CHECK_TIME=3
#mysqlis 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_helthif [ $MYSQL_OK = 1 ] ; then CHECK_TIME=0 exit 0fiif [ $MYSQL_OK -eq 0 ] &&[ $CHECK_TIME -eq 0 ]then pkill keepalived exit 1fisleep 1Done
Chmod 755 /root/keepalived_check_mysql.sh4、两台服务器同时启动mysql和keepalivedService keepalived restartService mysqld restart5、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。
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