keepalived实现MySQL MGR高可用（keepalived 2.2.7 + mysql 5.7.35）

#!/bin/bash
###使用说明开始###
#配合keepalived实现mysql mgr 集群高可用，流程如下
#1.如果mysql服务异常，启动服务
#2.如果mysql为master，则返回成功0，keepalived增加权重
#3.如果mysql为slave，则返回失败100，keepalived不增加权重
#4.如果mysql为slave，且keepalived为master，则keepalived切换
###使用说明结束###

#监控日志
source /etc/profile
vip="192.168.11.200"
monitorLogPath=/usr/local/ha_mysql/monitor.log
touch $monitorLogPath

#格式化日期时间
function getDatetime(){
    local cur=`date "+%Y-%m-%d %H:%M:%S"`
     echo $cur  
}

#获取local IP
function getLocalIp(){
    echo `ifconfig enp0s3 | grep -w "inet" | awk '{print $2}'`
}

#获取master IP
function getMasterIp(){
    echo `mysql -uroot -pxxxxxxx -e "SELECT * FROM performance_schema.replication_group_members WHERE MEMBER_ID = (SELECT VARIABLE_VALUE FROM performance_schema.global_status WHERE VARIABLE_NAME= 'group_replication_primary_member')" | awk 'NR==2{print($3)}'`
}

#检测keepalived是否master
function checkKeepalivedMaster(){
    local num=`ip a | grep "${vip}" | wc -l`
    if [ $num -eq 0 ];then
        echo 0
    else
        echo 1
    fi    
}

#检测mysql进程
function checkMysqlProcess(){
    #检测mysql服务，可以使用进程，也可以使用端口
    #此处检测mysql进程
    local num=`ps -C mysqld --no-header | wc -l`
    #local num=`netstat -lntup | grep -w 3307 | wc -l`
    if [ $num -eq 0 ];then
        echo 0
    else
        echo 1
    fi
}

#检测MGR Master
function checkMgrMaster(){
    #获取本机IP
    localIp=`getLocalIp`
    #获取mgr master ip
    masterIp=`getMasterIp`
    
    #判断当前实例是否为master
    if [ "${localIp}" = "${masterIp}" ];then
        echo 1
    else
        echo 0
    fi
}

#定义变量，mysql是否运行
run=`checkMysqlProcess`

#1.如果mysql服务异常，启动服务
if [ $run -eq 0 ];then
    #mysql异常，先启动mysql
    echo `getDatetime` "mysql error，start mysql" >> $monitorLogPath 
    service mysqld start
    run=`checkMysqlProcess`
    if [ $run -eq 0 ];then
        #启动mysql失败，停止keepalived服务，停止热备，触发keepalived切换
        echo `getDatetime` "start mysql failed" >> $monitorLogPath
    fi
#else
#    echo "mysql is alive"
fi

mgrMaster=`checkMgrMaster`
keepalivedMasger=`checkKeepalivedMaster`
if [ ${mgrMaster} -eq 1 ];then
    #2.如果mysql为master，则返回成功0，keepalived增加权重
    #echo `getDatetime` "mgr master，add priority" >> $monitorLogPath
    exit 0
else
    #3.如果mysql为slave，则返回失败100，keepalived不增加权重
    if [ ${keepalivedMasger} -eq 1 ];then
        #4.如果mysql为slave，且keepalived为master，则keepalived切换（服务重启）
        echo `getDatetime` "mgr slave，keepalived master，restart keepalived" >> $monitorLogPath
        service keepalived restart
        #keepalived服务重启，本脚本返回结果为重启前的keepalived进程，此时无需exit
    else
        #echo `getDatetime` "mgr slave，keepalived slave，keep priority" >> $monitorLogPath
        exit 100
    fi
fi