Environmental Science ：
        MySQL Master     192.168.135.139
        MySQL Slave       192.168.135.141
        VIP              192.168.135.188

First configure master-slave

https://blog.csdn.net/u010533511/article/details/88063523

master and slave All installed keepalived 

Download the package to be installed and send it to the server ：http://www.keepalived.org/download.html

My test catalog is ：/www/package/keepalived-2.0.13.tar.gz

#tar -zxvf keepalived-2.0.13.tar.gz
#cd keepalived-2.0.13
#./configure
# make && make install

#cp /www/package/keepalived-2.0.13/keepalived/etc/init.d/keepalived /etc/rc.d/init.d/
#cp /www/package/keepalived-2.0.13/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

#mkdir /etc/keepalived

#cp /www/package/keepalived-2.0.13/keepalived/etc/keepalived/keepalived.conf  etc/keepalived/
#cp /usr/local/sbin/keepalived /usr/sbin/
#chkconfig --add keepalived
#chkconfig --level 345 keepalived on

Some dependent packages may be required during installation , use yum Direct installation

Master slave configuration file modification  

master Configuration file for

#vim /etc/keepalived/keepalived.conf

global_defs {
   router_id MySQL-HA # function Keepalived A sign of the machine 
} 

vrrp_script check_run {
script "/home/mysql/mysql_check.sh"  # Configure the business process monitoring script 
interval 60  # Set the time interval for script execution , second 
}

vrrp_sync_group VG1 {
group {
VI_1
}
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33 # To change to the value of the current server 
    virtual_router_id 51
    priority 100  # The weight 
    advert_int 1
    nopreempt
    authentication {
        auth_type PASS
        auth_pass 1234
    }
    track_script {
    check_run
    }
    notify_master /home/mysql/master.sh
    notify_stop /home/mysql/stop.sh

    virtual_ipaddress {
        192.168.135.188
    }
}

 slave Of keepalived The configuration file :

#vim /etc/keepalived/keepalived.conf

global_defs {
   router_id MySQL-HA  # function Keepalived A sign of the machine 
} 

vrrp_script check_run {
script "/home/mysql/mysql_check.sh"  # Configure the business process monitoring script 
interval 60  # Set the time interval for script execution , second 
}

vrrp_sync_group VG1 {
group {
VI_1
}
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33 # To change to the value of the current server 
    virtual_router_id 51
    priority 90  # The weight 
    advert_int 1
    nopreempt 
    authentication {
        auth_type PASS
        auth_pass 1234
    }
    track_script {
    check_run
    }
    notify_master /home/mysql/master.sh
    notify_stop /home/mysql/stop.sh

    virtual_ipaddress {
        192.168.135.188
    }
}

master And slave Of keepalived There are only... In the configuration file priority Set different ,master by 100,slave by 90, Everything else is the same .

 /home/mysql/mysql_check.sh Documents are used to detect MySQL Whether the service is normal , When it is found that the connection is not connected mysql, Automatic handle keepalived Process kill , Give Way VIP Drift .

vim /home/mysql/mysql_check.sh

#!/bin/bash
. /home/mysql/.bashrc
count=1

while true
do

mysql -uroot -S /data/mysql.sock -e "show status;" > /dev/null 2>&1
i=$?
ps aux | grep mysqld | grep -v grep > /dev/null 2>&1
j=$?
if [ $i = 0 ] && [ $j = 0 ]
then
   exit 0
else
   if [ $i = 1 ] && [ $j = 0 ]
   then
       exit 0
   else
        if [ $count -gt 5 ]
        then
              break
        fi
   let count++
   continue
   fi
fi

done

home/mysql/master.sh The function of is to change the state to master Scripts to be executed later . First, determine if there is a delay in replication , If there's a delay , etc. 1 Minutes later , With or without delay , And stop copying , And record binlog and pos spot .

vim /home/mysql/master.sh

#!/bin/bash

. /home/mysql/.bashrc

Master_Log_File=$(mysql -uroot -S /data/mysql.sock -e "show slave status\G" | grep -w Master_Log_File | awk -F": " '{print $2}')
Relay_Master_Log_File=$(mysql -uroot -S /data/mysql.sock -e "show slave status\G" | grep -w Relay_Master_Log_File | awk -F": " '{print $2}')
Read_Master_Log_Pos=$(mysql -uroot -S /data/mysql.sock -e "show slave status\G" | grep -w Read_Master_Log_Pos | awk -F": " '{print $2}')
Exec_Master_Log_Pos=$(mysql -uroot -S /data/mysql.sock -e "show slave status\G" | grep -w Exec_Master_Log_Pos | awk -F": " '{print $2}')

i=1

while true
do

if [ $Master_Log_File = $Relay_Master_Log_File ] && [ $Read_Master_Log_Pos -eq $Exec_Master_Log_Pos ]
then
   echo "ok"
   break
else
   sleep 1

   if [ $i -gt 60 ]
   then
      break
   fi
   continue
   let i++
fi
done

mysql -uroot -S /data/mysql.sock -e "stop slave;"
mysql -uroot -S /data/mysql.sock -e "reset slave all;"
mysql -uroot -S /data/mysql.sock -e "reset master;"
mysql -uroot -S /data/mysql.sock -e "show master status;" > /tmp/master_status_$(date "+%y%m%d-%H%M").txt

home/mysql/stop.sh Express Keepalived Script to be executed after stopping . Check whether there are any copy and write operations , Finally, whether the execution is completed or not, exit . The contents of the document are as follows .

vim /home/mysql/stop.sh

#!/bin/bash

. /home/mysql/.bashrc

M_File1=$(mysql -uroot -S /data/mysql.sock -e "show master status\G" | awk -F': ' '/File/{print $2}')
M_Position1=$(mysql -uroot -S /data/mysql.sock -e "show master status\G" | awk -F': ' '/Position/{print $2}')
sleep 1
M_File2=$(mysql -uroot -S /data/mysql.sock -e "show master status\G" | awk -F': ' '/File/{print $2}')
M_Position2=$(mysql -uroot -S /data/mysql.sock -e "show master status\G" | awk -F': ' '/Position/{print $2}')

i=1

while true
do

if [ $M_File1 = $M_File1 ] && [ $M_Position1 -eq $M_Position2 ]
then
   echo "ok"
   break
else
   sleep 1

   if [ $i -gt 60 ]
   then
      break
   fi
   continue
   let i++
fi
done

Respectively in master Shanghe slave Start the keepalived process .

/etc/init.d/keepalived start ( Turn on )

/etc/init.d/keepalived stop ( Turn on )

Check the process

see vip

Client side usage VIP Connect to database , Create a test library , insert data .

When master Of mysql After hanging up

Will automatically switch to slave Then start it manually master after

Restart keepalived（ Restart both servers ） Then the master and slave will synchronize automatically It can be configured as a dual main structure , Ensure data integrity

keepalived.conf Configuration file parameter description

group： Set VRRP Instance name , There is only one example VI_1.
        vrrp_instance To configure VRRP example .VRRP The instance indicates that VRRP agreement . This example shows VRRP Some characteristics of , For example, master and slave 、VRID wait . You can open an instance on each network card .VRRP Examples mainly define vrrp_sync_group The drift of each group inside IP etc. .

state： Specify the initial state of the instance . After both routes are started , There will be competition soon , high priority Will run for Master, So here state That doesn't mean this one has always been Backup.
interface： Instance bound network card .
virtual_router_id：VRID Mark , The value is 0..255, The default... Is used here 51.
priority： The high priority campaign is Master,Master Above Backup At least 50. here MySQL The two priorities of master and slave libraries are set to 100 and 90, So when Keepalived After starting ,MySQL The main library will be selected Master.
advert_int： Check interval , This is set as the default 1 second .
nopreempt： Set to no preemption , Note that this configuration can only be set in state by BACKUP On a host of . When MASTER When something goes wrong ,BACKUP Will run for the new MASTER, So when the previous MASTER After being online again , Is to continue to be MASTER Or become BACKUP Well ？ No preemption is set by default , So what happened before MASTER When you get up, you will continue to seize and become MASTER. Such frequent switching is intolerable for business , We hope MASTER Get up and become BACKUP, So set no preemption . Again because nopreempt Configuration can only be used in state by BACKUP On a host of , therefore MASTER Of state It must also be set to BACKUP, in other words 192.168.135.139 and 192.168.135.141 All of them will state Set to BACKUP. Through two BACKUP The above settings are different priority, Let them come together and seize , high priority Of 192.168.135.139 Become the original MASTER.
authentication： Set the authentication type and authentication password . 
auth_type： Authentication type , Support PASS、AH Two kinds of , Usually use PASS type .
auth_pass： Plaintext authentication password . same VRRP Example of MASTER And BACKUP Use the same password to communicate properly .
track_script： Set the tracking script , Here for check_run, That is to call vrrp_script Script defined in . 
notify_master： Specify when switching to MASTER Script executed on .
notify_stop：VRRP Stop scripts that are executed later .
virtual_ipaddress： Specify the drift address （VIP）, That is, switch to MASTER when , these IP Or added , Switch to BACKUP when , these IP Will be deleted . Therefore, no virtual address can be bound to each server , And put them in virtual_ipaddress Inside , You can have more .Keepalived Will be used automatically ip addr Binding .

Reference resources ：https://blog.csdn.net/wzy0623/article/details/80916567