Rocky之Mysql-MHA高可用

9、半同步复制

安装插件三种方法：
第一种：
mysql>INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so' 安装
在写入配置文件开启：
[root@master ~]#vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
rpl_semi_sync_master_enabled=ON
rpl_semi_sync_master_timeout=3000
第二种方法：
[root@master ~]#vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
loose-rpl_semi_sync_master_enabled=ON  ## 仅报警
loose_rpl_semi_sync_master_timeout=3000
mysql>INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so' 安装
第三种：
[root@master ~]#vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
plugin-load-add = "semisync_salve.so"    开启服务自动加载插件
rpl_semi_sync_master_enabled=ON

# master：
[root@master ~]# mysql
mysql> install plugin rpl_semi_sync_master soname 'semisync_master.so';
[root@master ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=8
log-bin
rpl_semi_sync_master_enabled=ON
rpl_semi_sync_master_timeout=3000
[root@master ~]# systemctl restart mysqld.service
[root@master ~]# mysqldump -A -F --single-transaction --master-data=1 > /data/all.sql
[root@master ~]# scp /data/all.sql root@10.0.0.18:
[root@rocky8 ~]# scp /data/all.sql root@10.0.0.28:
[root@master ~]# mysql
mysql> show master logs;
+-------------------+-----------+-----------+
| Log_name          | File_size | Encrypted |
+-------------------+-----------+-----------+
| rocky8-bin.000001 |       179 | No        |
| rocky8-bin.000002 |       179 | No        |
| rocky8-bin.000003 |       204 | No        |
| rocky8-bin.000004 |       156 | No  

mysql> create user repluser@'10.0.0.%' identified by '123456';
mysql> grant replication slave on *.* to repluser@'10.0.0.%';
mysql> show global variables like '%semi%';

# slave
[root@slave ~]# mysql
mysql> install plugin rpl_semi_sync_slave soname 'semisync_slave.so';

CHANGE MASTER TO
  MASTER_HOST='10.0.0.8',
  MASTER_USER='repluser',
  MASTER_PASSWORD='123456',
  MASTER_PORT=3306,
  MASTER_LOG_FILE='rocky8-bin.000004',
  MASTER_LOG_POS=156,
  MASTER_CONNECT_RETRY=10;

[root@slave ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=18
rpl_semi_sync_slave_enabled=ON
[root@slave ~]# systemctl restart mysqld.service
[root@slave ~]# mysql
mysql> show global variables like '%semi%';
mysql> show slave status\G    #如果slave错误或者启动失败跳过错误或者重新写change master to

# slave2
[root@slave2 ~]# mysql
mysql> install plugin rpl_semi_sync_slave soname 'semisync_slave.so';
[root@slave2 ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=18
rpl_semi_sync_slave_enabled=ON
[root@slave2 ~]# systemctl restart mysqld.service
[root@slave2 ~]# mysql
mysql> source /root/all.sql
mysql> show slave status\G 

# 测试：
master 可以查看到2个客户端
mysql> show global status like '%semi%';
+--------------------------------------------+-------+
| Variable_name                              | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients               | 2  

两个从服务器都停止后，主服务器更改内容后，等待3秒，自动提交成功。

10、复制过滤器

两种方法实现过滤：
第一种：master服务器选项写黑名单或者白名单：
[mysqld]
server-id=8
log-bin
rpl_semi_sync_master_enabled=ON
rpl_semi_sync_master_timeout=3000
binlog-ignore-db=db1               #黑名单：不同步db1库
重启服务即可

11、GTID复制

# master：#从库如果数据不一致，需要提前完全备份
[root@master ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=8
gtid_mode=ON
enforce_gtid_consistency
log-bin=/data/mysql/mysql-bin
[root@master ~]# mkdir /data/mysql
[root@master ~]# chown -R mysql.mysql /data/mysql
[root@master ~]# systemctl start mysqld.service 

# slave：
[mysqld]
server-id=18
gtid_mode=ON
enforce_gtid_consistency
[root@slave ~]# systemctl start mysqld.service
CHANGE MASTER TO
  MASTER_HOST='10.0.0.8',
  MASTER_USER='repluser',
  MASTER_PASSWORD='123456',
  MASTER_PORT=3306,
  MASTER_AUTO_POSITION=1;
  mysql> start slave;
mysql> show slave status\G

12、利用 Mycat 实现 MySQL 的读写分离

所有主机的系统环境：
Mycat: 10.0.0.38 #内存建议2G以上（java需要大内存）
master: 10.0.0.8 MySQL 8.0
slave: 10.0.0.18 MySQL 8.0
关闭SELinux和防火墙、时间同步

主从和上边配置一样(从自动同步)：
master:
mysql> create user wang@'10.0.0.%' identified by '123456';
mysql> grant all on *.* to wang@'10.0.0.%';

Mycat：
[root@mycat ~]# yum install -y java
[root@mycat ~]#mkdir /apps
[root@mycat ~]#tar xf Mycat-server-1.6.7.6-release-20220524173810-linux.tar.gz -C /apps/
[root@mycat ~]#cd /apps/
[root@mycat apps]#echo 'PATH=/apps/mycat/bin:$PATH' > /etc/profile.d/mycat.sh
[root@mycat apps]#. /etc/profile.d/mycat.sh
[root@mycat apps]#mycat start
Starting Mycat-server...
[root@mycat apps]#ss -ntl

现在可以测试连接：
客户机（要有mysql客户端）：
[root@rocky8 ~]# mysql -uroot -p123456 -h10.0.0.38 -P8066
mysql> show databases;
+----------+
| DATABASE |
+----------+
| TESTDB   |
+----------+
[root@mycat mycat]#vim conf/server.xml
 <property name="serverPort">3306</property>   #修改8066端口为3066，此行（45行）默认是注释的，可以复制到53行左右为注释的地方
 用户名密码在最后方，有两块有用户名密码，一个库级别的一个表级别的。

[root@mycat mycat]#vim conf/schema.xml      #仅对hellodb库进行了读写分离
<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">
    <schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="dn1">
    </schema>
    <dataNode name="dn1" dataHost="localhost1" database="hellodb" />
    <dataHost name="localhost1" maxCon="1000" minCon="10" balance="1"
              writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
        <heartbeat>select user()</heartbeat>
        <writeHost host="host1" url="10.0.0.8:3306" user="wang" password="123456">
         <readHost host="host2" url="10.0.0.18:3306" user="wang" password="123456" />
		 <readHost host="host3" url="10.0.0.28:3306" user="wang" password="123456" />
        </writeHost>
    </dataHost>
</mycat:schema>

# 客户机连接测试
[root@rocky8 ~]# mysql -uroot -p123456 -h10.0.0.38
mysql> select @@server_id;   #可以看到server-id是28
+-------------+
| @@server_id |
+-------------+
|          28 |
+-------------+
1 row in set (0.11 sec)

mysql> select @@server_id;   #可以看到server-id是18
+-------------+
| @@server_id |
+-------------+
|          18 |
+-------------+
## 上述已经测试好了读在18和28直接跳跃
## 下面测试写：
客户机连接mycat执行：
mysql> USE TESTDB;
mysql> insert students (name,age)values('wangwangwang',30);
在主服务可以看到
  26 | wangwangwang  |  30 | F      |    NULL |      NULL |

  [root@master ~]# systemctl stop mysqld.service   #停止主的服务
# mycat插入数据报错：
mysql> insert students(name,age)values('zhangzhangzhang',20);
ERROR 1184 (HY000): java.net.ConnectException: Connection refused
[root@master ~]# systemctl start mysqld.service  #开启主服务 mycat再次可以插入
mysql> insert students(name,age)values('zhangzhangzhang',20);
Query OK, 1 row affected (0.01 sec)

13、综合实验1

#环境：
master: 10.0.0.8   rocky8.6
slave:  10.0.0.18   rocky8.6
slave1: 10.0.0.28   rocky8.6
Mycat:  10.0.0.38   rocky8.6
MHA manager: 10.0.0.188   centos7
#流程：
1、先实现半同步主从
2、加入Gtid复制
3、增加Mycat读写分离
4、建立MHA高可用
# 需提前准备
Mycat安装包： Mycat-server-1.6.7.6-release-20220524173810-linux.tar.gz
MHA管理安装包和节点安装包：
  - mha4mysql-manager-0.58-0.el7.centos.noarch.rpm
  - mha4mysql-node-0.58-0.el7.centos.noarch.rpm
VIP自动飘逸脚本： master_ip_failover
邮件自动发送脚本： sendmail.sh
打通所有节点ssh脚本： ssh_key_for_linux.sh
Mycat设置模板：
  - server.xml
  - schema.xml
MHA设置模板： app1.cnf

----------------------------半同步复制 ------------------------
#master：
[root@master ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=8
log-bin=/data/mysql/mysql-bin
[root@master ~]# systemctl restart mysqld.service
[root@master ~]# mysql
mysql> install plugin rpl_semi_sync_master soname 'semisync_master.so';
[root@master ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=8
log-bin=/data/mysql/mysql-bin
rpl_semi_sync_master_enabled=ON
rpl_semi_sync_master_timeout=3000
[root@master ~]# mkdir /data/mysql
[root@master ~]# chown -R mysql.mysql /data/mysql
[root@master ~]# mysqldump -A -F --single-transaction --master-data=1 > all.sql
[root@master ~]# scp all.sql root@10.0.0.18:
[root@master ~]# scp all.sql root@10.0.0.28:
[root@master ~]# systemctl restart mysqld.service

[root@master ~]# mysql
mysql> show master logs;
+------------------+-----------+-----------+
| Log_name         | File_size | Encrypted |
+------------------+-----------+-----------+
| mysql-bin.000001 |       156 | No        |
+------------------+-----------+-----------+
1 row in set (0.00 sec)

mysql> create user repluser@'10.0.0.%' identified by '123456';
Query OK, 0 rows affected (3.01 sec)

mysql> grant replication slave on *.* to repluser@'10.0.0.%';
Query OK, 0 rows affected (0.00 sec)

#slave
[root@slave ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=18
log-bin=/data/mysql/mysql-bin
[root@slave ~]# mkdir /data/mysql
[root@slave ~]# chown -R mysql.mysql /data/mysql
[root@slave ~]# systemctl restart mysqld.service
[root@slave ~]# mysql
mysql> install plugin rpl_semi_sync_slave soname 'semisync_slave.so';
mysql> set sql_log_bin=0;
mysql> source /root/all.sql
mysql> set sql_log_bin=1;
CHANGE MASTER TO
  MASTER_HOST='10.0.0.8',
  MASTER_USER='repluser',
  MASTER_PASSWORD='123456',
  MASTER_PORT=3306,
  MASTER_LOG_FILE='mysql-bin.000001',
  MASTER_LOG_POS=156,
  MASTER_CONNECT_RETRY=10;
[root@slave ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=18
log-bin=/data/mysql/mysql-bin
rpl_semi_sync_slave_enabled=ON
[root@slave ~]# systemctl restart mysqld.service
[root@slave ~]# mysql
mysql> start slave;
mysql> show slave status\G

# slave1的操作步骤同slave

========================GTID============================
在上边半同步的基础上增加：
# master:
[root@master ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=8
log-bin=/data/mysql/mysql-bin
rpl_semi_sync_master_enabled=ON
rpl_semi_sync_master_timeout=3000
gtid_mode=ON                       #开启gtid
enforce_gtid_consistency           #保证GTID安全参数
[root@master ~]# systemctl restart mysqld.service

# slave和slave1同样在配置文件增加gtid的两行，重启服务即可
进入mysql master可以通过mysql> show master status;查看gtid 信息，一般需要同步过一次后才会显示。
slave可以通过mysql> show slave status\G 查看Gtid信息。

=================Mycat===============
# mycat:
[root@mycat ~]#yum install -y java
[root@mycat ~]#java -version
openjdk version "1.8.0_332"
[root@mycat ~]#mkdir /apps
[root@mycat ~]#tar xf Mycat-server-1.6.7.6-release-20220524173810-linux.tar.gz -C /apps/
[root@mycat ~]#echo 'PATH=/apps/mycat/bin:$PATH' > /etc/profile.d/mycat.sh
[root@mycat ~]#. /etc/profile.d/mycat.sh

[root@mycat mycat]#vim conf/server.xml
 <property name="serverPort">3306</property>   #修改8066端口为3066，此行（45行）默认是注释的，可以复制到53行左右为注释的地方

[root@mycat mycat]#vim conf/schema.xml
<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">
    <schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="dn1">
    </schema>
    <dataNode name="dn1" dataHost="localhost1" database="hellodb" />
    <dataHost name="localhost1" maxCon="1000" minCon="10" balance="1"
              writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
        <heartbeat>select user()</heartbeat>
        <writeHost host="host1" url="10.0.0.8:3306" user="li" password="123456">
         <readHost host="host2" url="10.0.0.18:3306" user="li" password="123456" />
		 <readHost host="host3" url="10.0.0.28:3306" user="li" password="123456" />
        </writeHost>
    </dataHost>
</mycat:schema>

# master
mysql> create user li@'10.0.0.%' identified by '123456';
mysql> grant all on *.* to li@'10.0.0.%';

# client测试：
[root@rocky8 ~]# mysql -uroot -p123456 -h10.0.0.38
mysql> show databases;
mysql> use TESTDB;
mysql> select @@server_id;
+-------------+
| @@server_id |
+-------------+
|          28 |
+-------------+
1 row in set (0.01 sec)

mysql> select @@server_id;
+-------------+
| @@server_id |
+-------------+
|          18 |
+-------------+
1 row in set (0.00 sec)

# MHA(centos7):
=======================在所有节点实现相互之间 ssh key 验证========================
# 修改下边脚本的密码变量PASS和网卡接口：

[root@MHA ~]# vim ssh_key_for_linux.sh
PASS=redhat          # 密码为redhat
END=254
IP=`ip a s ens33 | awk -F'[ /]+' 'NR==3{print $3}'`    #网卡名称为ens33
NET=${IP%.*}.

. /etc/os-release

rm -f /root/.ssh/id_rsa
[ -e ./SCANIP.log ] && rm -f SCANIP.log

for((i=3;i<="$END";i++));do
    ping -c 1 -w 1  ${NET}$i &> /dev/null  && echo "${NET}$i" >> SCANIP.log &
done
wait

ssh-keygen -P "" -f /root/.ssh/id_rsa
if [ $ID = "centos" -o $ID = "rocky" ];then
    rpm -q sshpass || yum -y install sshpass
else
    dpkg -i sshpass &> /dev/null ||{ apt update; apt -y install sshpass; }
fi

sshpass -p $PASS ssh-copy-id -o StrictHostKeyChecking=no $IP

AliveIP=(`cat SCANIP.log`)
for n in ${AliveIP[*]};do
    sshpass -p $PASS scp -o StrictHostKeyChecking=no -r /root/.ssh root@${n}:
done

#把.ssh/known_hosts拷贝到所有主机，使它们第一次互相访问时不需要输入回车
for n in ${AliveIP[*]};do
    scp /root/.ssh/known_hosts ${n}:.ssh/
done

[root@MHA ~]# chmod +x ssh_key_for_linux.sh
[root@MHA ~]# ./ssh_key_for_linux.sh

===========================安装相关包=======================================
# MHA服务器安装mha4mysql-manager和node  （建议先安装manager后安装node）
[root@MHA ~]# yum install -y epel-release mha4mysql-manager-0.58-0.el7.centos.noarch.rpm mha4mysql-node-0.58-0.el7.centos.noarch.rpm   ## (没有epel源的话安装manager会报错)
# 所有mysql主从服务器安装mha4mysql-node
[root@master ~]# yum install -y mha4mysql-node-0.58-0.el7.centos.noarch.rpm
[root@slave ~]# yum install -y mha4mysql-node-0.58-0.el7.centos.noarch.rpm
[root@slave1 ~]# yum install -y mha4mysql-node-0.58-0.el7.centos.noarch.rpm

# 准备相关脚本和配置mha4mysql-manager配置
# MHA:
=======================master_ip_failover脚本=====================
[root@MHA ~]# cat /usr/local/bin/master_ip_failover
#!/usr/bin/env perl
use strict;
use warnings FATAL => 'all';
use Getopt::Long;
use MHA::DBHelper;
my (
$command, $ssh_user, $orig_master_host,
$orig_master_ip, $orig_master_port, $new_master_host,
$new_master_ip, $new_master_port, $new_master_user,
$new_master_password
);
#执行时必须删除下面三行注释
my $vip = '10.0.0.188/24';  # 修改这里的ip, 找个空闲的ip, 不能是在用的
my $key = "1";
my $ssh_start_vip = "/sbin/ifconfig eth0:$key $vip";　　# 这里和下一行需要注意下网卡信息,我是用的虚拟机网卡是eth0, 需修改成机器的网卡信息
my $ssh_stop_vip = "/sbin/ifconfig eth0:$key down";
GetOptions(
'command=s' => \$command,
'ssh_user=s' => \$ssh_user,
'orig_master_host=s' => \$orig_master_host,
'orig_master_ip=s' => \$orig_master_ip,
'orig_master_port=i' => \$orig_master_port,
'new_master_host=s' => \$new_master_host,
'new_master_ip=s' => \$new_master_ip,
'new_master_port=i' => \$new_master_port,
'new_master_user=s' => \$new_master_user,
'new_master_password=s' => \$new_master_password,
);
exit &main();
sub main {
if ( $command eq "stop" || $command eq "stopssh" ) {
# $orig_master_host, $orig_master_ip, $orig_master_port are passed.
# If you manage master ip address at global catalog database,
# invalidate orig_master_ip here.
my $exit_code = 1;
eval {
# updating global catalog, etc
$exit_code = 0;
};
if ($@) {
warn "Got Error: $@\n";
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "start" ) {
# all arguments are passed.
# If you manage master ip address at global catalog database,
# activate new_master_ip here.
# You can also grant write access (create user, set read_only=0, etc) here.
my $exit_code = 10;
eval {
print "Enabling the VIP - $vip on the new master - $new_master_host
\n";
&start_vip();
&stop_vip();
$exit_code = 0;
};
if ($@) {
warn $@;
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "status" ) {
print "Checking the Status of the script.. OK \n";
`ssh $ssh_user\@$orig_master_host \" $ssh_start_vip \"`;
exit 0;
}
else {
&usage();
exit 1;
}
}
sub start_vip() {
`ssh $ssh_user\@$new_master_host \" $ssh_start_vip \"`;
}
# A simple system call that disable the VIP on the old_master
sub stop_vip() {
`ssh $ssh_user\@$orig_master_host \" $ssh_stop_vip \"`;
}
sub usage {
print
"Usage: master_ip_failover --command=start|stop|stopssh|status --
orig_master_host=host --orig_master_ip=ip --orig_master_port=port --
new_master_host=host --new_master_ip=ip --new_master_port=port\n";
}

[root@MHA ~]# chmod +x /usr/local/bin/master_ip_failover
=======================sendmail.sh脚本============================================
vim /usr/local/bin/sendmail.sh
#!/bin/bash
echo "MHA is failover!" | mail -s "MHA Warning" 965507991@qq.com
[root@MHA ~]# chmod +x /usr/local/bin/sendmail.sh

[root@MHA ~]# yum install -y mailx
[root@MHA ~]# vim /etc/mail.rc    #在最后添加以下自己的邮箱信息
set from=96550@qq.com          #自己的邮箱
set smtp=smtp.qq.com           #邮箱的smtp服务器
set smtp-auth-user=96550@qq.com #邮箱用户名
set smtp-auth-password=arxbgiznng   #邮箱smtp授权码
[root@MHA ~]# bash /usr/local/bin/sendmail.sh   #测试邮箱是否能收到邮件

=================================建立配置文件==================================
[root@MHA ~]# mkdir /etc/mastermha
[root@MHA ~]# vim /etc/mastermha/app1.cnf

[server default]
check_repl_delay=0
manager_log=/data/mastermha/app1/manager.log
manager_workdir=/data/mastermha/app1/
remote_workdir=/data/mastermha/app1/
master_binlog_dir=/data/mysql/
master_ip_failover_script=/usr/local/bin/master_ip_failover
ping_interval=1
repl_user=repluser
repl_password=123456
report_script=/usr/local/bin/sendmail.sh
ssh_user=root
user=mhauser
password=123456

[server1]
hostname=10.0.0.8
candidate_master=1

[server2]
hostname=10.0.0.18

[server3]
candidate_master=1
hostname=10.0.0.28

# master：
[root@master ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=8
log-bin=/data/mysql/mysql-bin
rpl_semi_sync_master_enabled=ON
rpl_semi_sync_master_timeout=3000
gtid_mode=ON
enforce_gtid_consistency
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysql/mysqld.log
pid-file=/run/mysqld/mysqld.pid
skip_name_resolve=1                  #增加（可选） 禁止反向解析
general_log                  #方便观察的设置 （开启通用日志）
[root@master ~]# systemctl restart mysqld.service
[root@master ~]# ifconfig eth0:1 10.0.0.188/24
[root@master ~]# mysql
mysql> create user mhauser@'10.0.0.%' identified by '123456';
mysql> grant all on *.* to mhauser@'10.0.0.%';
# slave：
[root@slave ~]# vim /etc/my.cnf.d/mysql-server.cnf
[mysqld]
server-id=18
log-bin=/data/mysql/mysql-bin
rpl_semi_sync_slave_enabled=ON
gtid_mode=ON
enforce_gtid_consistency
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysql/mysqld.log
pid-file=/run/mysqld/mysqld.pid
read_only       #只读
relay_log_purge=0 #禁止自动删除不再使用的relay log
skip_name_resolve=1 #禁止反向解析,此项可选
general_log

[root@slave ~]# systemctl restart mysqld.service

# slave2 配置同slave
=========================================
# MHA:
[root@MHA ~]# masterha_check_ssh --conf=/etc/mastermha/app1.cnf     #检查环境
[root@MHA ~]# masterha_check_repl --conf=/etc/mastermha/app1.cnf     #如果出错，检查配置和脚本
[root@MHA ~]# masterha_check_status --conf=/etc/mastermha/app1.cnf  #查看状态，现在是no running
[root@MHA ~]# masterha_manager --conf=/etc/mastermha/app1.cnf --remove_dead_master_conf --ignore_laste_failover  #启动MHA ，生产环境一般后台运行，需要在头前加nohup 尾部加&> /dev/null

再开个窗口查看状态：
[root@MHA ~]# masterha_check_status --conf=/etc/mastermha/app1.cnf      #查看状态
app1 (pid:15957) is running(0:PING_OK), master:10.0.0.8

# 模拟故障：
[root@master ~]# systemctl stop mysqld.service   #10.0.0.8主服务器停止服务

MHA查看日志：
[root@MHA ~]# tail /data/mastermha/app1/manager.log  -f
......
Master 10.0.0.8(10.0.0.8:3306) is down!
Started automated(non-interactive) failover.
Invalidated master IP address on 10.0.0.8(10.0.0.8:3306)
The latest slave 10.0.0.18(10.0.0.18:3306) has all relay logs for recovery.
Selected 10.0.0.28(10.0.0.28:3306) as a new master.
10.0.0.28(10.0.0.28:3306): OK: Applying all logs succeeded.
10.0.0.28(10.0.0.28:3306): OK: Activated master IP address.
10.0.0.18(10.0.0.18:3306): This host has the latest relay log events.
Generating relay diff files from the latest slave succeeded.
10.0.0.18(10.0.0.18:3306): OK: Applying all logs succeeded. Slave started, replicating from 10.0.0.28(10.0.0.28:3306)
10.0.0.28(10.0.0.28:3306): Resetting slave info succeeded.
Master failover to 10.0.0.28(10.0.0.28:3306) completed successfully.
Sat Sep  3 15:51:06 2022 - [info] Sending mail..
[root@MHA ~]# cat /etc/mastermha/app1.cnf   #查看配置文件，原主服务器8的地址已经被删除
[server2]
hostname=10.0.0.18

[server3]
candidate_master=1
hostname=10.0.0.28

# 邮箱也收到了邮件。

# slave 18主机查看状态：
mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for source to send event
                  Master_Host: 10.0.0.28
                  Master_User: repluser
# 原slave1 28主机已成为新的主服务器，验证VIP飘逸：
[root@slave1 ~]# ip a
eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:5d:78:d1 brd ff:ff:ff:ff:ff:ff
    inet 10.0.0.28/24 brd 10.0.0.255 scope global noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet 10.0.0.188/24 brd 10.0.0.255 scope global secondary eth0:1
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe5d:78d1/64 scope link
       valid_lft forever preferred_lft forever

# 再次运行MHA，需要删除下面文件：
# MHA删除：[root@MHA ~]# rm -rf /data/mastermha/app1/
# 所有节点删除：
[root@master ~]# rm -rf /data/mastermha/app1/
[root@slave ~]# rm -rf /data/mastermha/app1/
[root@slave1 ~]# rm -rf /data/mastermha/app1/

# 原来的10.0.0.8变为从服务器
mysql> CHANGE MASTER TO
    ->   MASTER_HOST='10.0.0.28',
    ->   MASTER_USER='repluser',
    ->   MASTER_PASSWORD='123456',
    ->   MASTER_PORT=3306,
    ->   MASTER_AUTO_POSITION=1;
Query OK, 0 rows affected, 8 warnings (0.06 sec)

mysql> start slave;
Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for source to send event
                  Master_Host: 10.0.0.28

# MHA配置新加入一个IP服务器在开启masterha即可