十一、MYSQL 基于MHA的高可用集群

一、MHA概述

1、简介

2、MHA 特点

3、MHA 工作原理（流程）

二、MHA高可用结构部署

1、环境准备

2、安装MHA 监控manager

3、在manager管理机器上配置管理节点：

4、编master_ip_failover脚本写

5、在master上创建mha这个用户来访问数据库节点：

6、配置无密码认证

7、进行检测工作，检测ssh免密和主从，在manager上执行：

8、检测没问题就在master主节点上手动配置VIP

9、检测没有报错，就可以在manager上启动MHA

三、故障模拟测试

1、先在manager上监控日志

2、在master停掉MySQL服务，观察manager的日志

3、在master上可以看到虚拟的VIP,已经消失，查看从节点，可以看到VIP，如下图

4、查看manager日志

5、MHA发生切换之后

四、将宕机的MySQL，恢复为master

1、先将mysql1设置成master（mysql2）的从服务器，设置只读

2、关掉当前master（mysql2）的同步功能，否则从服务器会报错

3、手动修改manager上的app1.cnf配置

4、检查无密码认证和 MySQL 主从状态是否正常，启动MHA

5、查看当前主库master

6、关闭MHA

7、在manager上手动关闭当前master

8、在manager上手动设置新的master

9、启动MHA

10、检查状态看看master是否切换成功

五、遇到的问题

1、

2、

3、启动MHA时报错

4、当主库挂了 MHA日志报错

5、

6、

能力有限，不足之处，请大家批评指正。

上一章安装了mysql以及搭建了主从复制。接下来搭建MHA基于MySQL的高可用

一、MHA概述

1、简介

目前mysql高可用方面是一个相对成熟的解决方案，MHA是一套优秀的MySQL故障切换和主从复制的高可用软件

在MySQL故障切换过程中，MHA能做到0-30秒之内完成数据库的故障切换操作，并且在进行故障切换过程中，MHA能够最大程度上保证数据的一致性，已达到真正意义上的高可用。

MHA里有两个角色，一个是MHA Node（数据节点）另一个是MHA Manager（管理节点）。

MHA MAster节点可以单独部署在一台独立的机器上管理多个master-slave集群，也可以部署在一台slave节点上，MHA Manager会定时探测集群中的master节点，当master出现故障时，它可以自动将最新数据的slave提升为master，然后将所有其他的slave重新指向新的master。整个故障转移过程对应用程序完全透明。

MHA Node运行在每台MySQL服务器上，它通过监控具备解析清理logs功能的脚本来加快故障转移的。

2、MHA 特点

自动故障切换过程中，MHA总会试图从宕机的主服务器上保存二进制日志，最大程度的保证数据不丢失。但是并不总是可行的，例如，如果主服务器硬件故障或者无法通过SSH访问，MHA则无法保存二进制日志，只能进行故障转移而丢失了最新的数据。此时，使用MySQL5.5的半同步复制，可以大大降低数据丢失的风险，MHA可以与半同步复制结合起来，如果只有一个slave已经收到了最新的二进制日志，MHA可以将最新的二进制日志应用于其他所有的slave服务器上，因此可以保证所有节点的数据一致性，有时候可故意设置从节点慢于主节点，当发生意外删除数据库导致数据丢失时，可从从节点二进制日志中恢复。

3、MHA 工作原理（流程）

MHA 有3个部分

核心是主从
Manager管理节点：管理数据库集群信息，定义、触发故障切换
Node数据节点：主要负责保存日志，比较中继日志，选择主备

MHA会通过Node监控MySQL数据库服务的节点信息，定期检测和返回Master角色的健康状态（健康检查），MHA通过将VIP定义在Master节点上，并且数据库的访问也是从此VIP进入，当Master异常时，MHA会进行“故障切换”，就是VIP漂移。

工作原理：

从宕机崩溃的master保存二进制日志事件（binlog events）
识别含有最新更新的slave
应用差异的中继日志（relay log）到其他slave
应用从master保存的二进制日志事件
提升一个slave为新的master
使其他slave连接新的master进行复制

二、MHA高可用结构部署

1、环境准备

服务器	IP	MHA
192.168.134.132	Master	node
192.168.134.133	Slave	manager
192.168.134.134	Slave	node
192.168.134.100/24	VIP

#首先检查软件是否已经安装1、如果是rpm安装的，可以用rpm -qa |grep 软件包名字  检查2、如果是yum方式安装的，可以用 yum list installed |grep 软件包名字  检查 
#1、所有节点安装MHA node 相关依赖：yum -y install epel-releaseyum -y install perl-DBD-MySQL perl-DBI ncftp
#2、安装mha node： yum -y install https://github.com/yoshinorim/mha4mysql-node/releases/download/v0.58/mha4mysql-node-0.58-0.el7.centos.noarch.rpm    #scp传到其他机器scp -r mha4mysql-node-0.58-0.el7.centos.noarch.rpm root@192.168.134.133:/usr/local/MHA/#安装[root@rabbitmq_2 MHA]# rpm -ivh mha4mysql-node-0.58-0.el7.centos.noarch.rpm准备中...                          ################################# [100%]正在升级/安装...1:mha4mysql-node-0.58-0.el7.centos ################################# [100%]所有从节点rpm安装 Node组件之后，会在/usr/bin 下有这几个脚本文件save_binary_logs             保存和复制 master 的二进制日志apply_diff_relay_logs        识别差异的中继日志事件并将其差异的事件应用于其他的 slavefilter_mysqlbinlog           去除不必要的 ROLLBACK 事件

2、安装MHA 监控manager

安装在192.168.134.133机器上

#下载地址yum -y install https://github.com/yoshinorim/mha4mysql-manager/releases/download/v0.58/mha4mysql-manager-0.58-0.el7.centos.noarch.rpm#下载好了之后，先安装依赖
[root@rabbitmq_2 yum-root-nm0sqp]# yum -y install epel-release
[root@rabbitmq_2 yum-root-nm0sqp]# yum -y install perl-Config-Tiny perl-Time-HiRes perl-Parallel-ForkManager perl-Log-Dispatch perl-DBD-MySQL ncftp
已加载插件：fastestmirror, langpacks
Loading mirror speeds from cached hostfile* base: mirrors.163.com* epel: ftp.yz.yamagata-u.ac.jp* extras: mirrors.163.com* updates: mirrors.aliyun.com
软件包 perl-Config-Tiny-2.14-7.el7.noarch 已安装并且是最新版本
软件包 4:perl-Time-HiRes-1.9725-3.el7.x86_64 已安装并且是最新版本
软件包 perl-Parallel-ForkManager-1.18-2.el7.noarch 已安装并且是最新版本
软件包 perl-Log-Dispatch-2.41-1.el7.1.noarch 已安装并且是最新版本
软件包 perl-DBD-MySQL-4.023-6.el7.x86_64 已安装并且是最新版本
软件包 2:ncftp-3.2.5-7.el7.x86_64 已安装并且是最新版本
无须任何处理
[root@rabbitmq_2 yum-root-nm0sqp]# 
# manager包安装
[root@rabbitmq_2 yum-root-nm0sqp]# rpm -ivh mha4mysql-manager-0.58-0.el7.centos.noarch.rpm 
准备中...                          ################################# [100%]软件包 mha4mysql-manager-0.58-0.el7.centos.noarch 已经安装
[root@rabbitmq_2 yum-root-nm0sqp]# 
# Manager组件安装之后，会在/usr/bin 有以下脚本
[root@rabbitmq_2 bin]# ls |grep masterha
masterha_check_repl    #检查 MySQL 复制状况
masterha_check_ssh    # 检查 MHA 的 SSH 配置状况
masterha_check_status    #检测当前 MHA 运行状态
masterha_conf_host    #添加或删除配置的 server 信息
masterha_manager    #启动 manager的脚本
masterha_master_monitor    #检测 master 是否宕机
masterha_master_switch    #控制故障转移（自动或者手动）
masterha_secondary_check    #
masterha_stop    #关闭manager

3、在manager管理机器上配置管理节点：

#创建相关目录
mkdir /home/mha/conf    #配置文件
mkdir /home/mha         #工作目录
mkdir /home/mha/log     #日志目录
mkdir /home/mha/bin     #脚本路径#编写配置文件
vim /home/mha/conf/mysql_mha.cnf
#添加
[server default]
#mha访问数据库的账号与密码
user=mha
password=xxxxxx
port=3306
#使用ssh登录时的用户
ssh_user=root
#指定mha的工作目录
manager_workdir=/home/mha/
#指定管理日志路径
manager_log=/home/mha/log/manager.log
#指定master节点存放binlog的日志文件的目录 log_bin=mysql_bin默认是在/var/lib/mysql
master_binlog_dir=/var/lib/mysql
#指定mha在远程节点上的工作目录
remote_workdir=/home/mha/
#指定主从复制的mysq用户和密码
repl_user=repl
repl_password=123456
#指定检测间隔时间
ping_interval=3
ping_type=insert//更高效
#指定一个脚本，该脚本实现了在主从切换之后，将虚拟ip漂移到新的master上
master_ip_failover_script=/home/mha/bin/master_ip_failover
#设置手动切换时的切换脚本位置
master_ip_online_change_script=/home/mha/bin/master_ip_online_change
#指定用于二次检查节点状态的节点，这里不要配置主节点的ip，否则主节点网络断掉或者机器断电就无法切换
secondary_check_script=/usr/bin/masterha_secondary_check -s 192.168.134.133 -s 192.168.134.134
#用于故障切换的时候发送邮件提醒的脚本，不用就注释掉
#report_script=/home/mha/bin/send_mail
log_level=debug  //日志格式[server1]
hostname=192.168.134.132
port=3306[server2]
hostname=192.168.134.133
port=3306no_master=1
ignore_fail=1[server3]
hostname=192.168.134.134port=3306
candidate_master=1
#设置为候选master，设置该参数以后，发生主从切换以后将会将此从库提升为主库，即使这个主库不是集群中最新的slave
check_repl_delay=0

4、编master_ip_failover脚本写

#!/usr/bin/env perluse strict;
use warnings FATAL => 'all';use Getopt::Long;my ($command, $orig_master_host, $orig_master_ip,$ssh_user,$orig_master_port, $new_master_host, $new_master_ip,$new_master_port,$orig_master_ssh_port,$new_master_ssh_port,$new_master_user,$new_master_password
);# 这里定义的虚拟IP配置要注意，这个ip必须要与你自己的集群在同一个网段，否则无效
my $vip = '192.168.134.100/24';
my $key = '1';
# 这里的网卡名称 “ens33” 需要根据你机器的网卡名称进行修改
# 如果多台机器直接的网卡名称不统一，有两种方式，一个是改脚本，二是把网卡名称修改成统一
# 我这边实际情况是修改成统一的网卡名称
my $ssh_start_vip = "sudo /sbin/ifconfig ens33:$key $vip";
my $ssh_stop_vip = "sudo /sbin/ifconfig ens33:$key down";
my $ssh_Bcast_arp= "sudo /sbin/arping -I bond0 -c 3 -A $vip";GetOptions('command=s'          => \$command,'ssh_user=s'         => \$ssh_user,'orig_master_host=s' => \$orig_master_host,'orig_master_ip=s'   => \$orig_master_ip,'orig_master_port=i' => \$orig_master_port,'orig_master_ssh_port=i' => \$orig_master_ssh_port,'new_master_host=s'  => \$new_master_host,'new_master_ip=s'    => \$new_master_ip,'new_master_port=i'  => \$new_master_port,'new_master_ssh_port' => \$new_master_ssh_port,'new_master_user' => \$new_master_user,'new_master_password' => \$new_master_password);exit &main();sub main {$ssh_user = defined $ssh_user ? $ssh_user : 'root';print "\n\nIN SCRIPT TEST====$ssh_user|$ssh_stop_vip==$ssh_user|$ssh_start_vip===\n\n";if ( $command eq "stop" || $command eq "stopssh" ) {my $exit_code = 1;eval {print "Disabling the VIP on old master: $orig_master_host \n";&stop_vip();$exit_code = 0;};if ($@) {warn "Got Error: $@\n";exit $exit_code;}exit $exit_code;}elsif ( $command eq "start" ) {my $exit_code = 10;eval {print "Enabling the VIP - $vip on the new master - $new_master_host \n";&start_vip();&start_arp();$exit_code = 0;};if ($@) {warn $@;exit $exit_code;}exit $exit_code;}elsif ( $command eq "status" ) {print "Checking the Status of the script.. OK \n";exit 0;}else {&usage();exit 1;}
}sub start_vip() {`ssh $ssh_user\@$new_master_host \" $ssh_start_vip \"`;
}
sub stop_vip() {`ssh $ssh_user\@$orig_master_host \" $ssh_stop_vip \"`;
}sub start_arp() {`ssh $ssh_user\@$new_master_host \" $ssh_Bcast_arp \"`;
}
sub usage {print"Usage: master_ip_failover --command=start|stop|stopssh|status --ssh_user=user --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";
}#给脚本添加可执行权限
chmod 777 master_ip_failover#在所有节点都创建 MHA 工作目录
mkdir /home/mha

5、在master上创建mha这个用户来访问数据库节点：

mysql -uroot -p'xxxxxx' 
create user 'mha'@'%' identified with mysql_native_password by 'xxxxxx';
grant all privileges on *.* to 'mha'@'%';
flush privileges;#如果提示报错，看报错内容，应该是密码策略的问题，把密码策略改了就可以
mysql> create user 'mha'@'%' identified with mysql_native_password by 'xxxxxx';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
mysql> mysql> set global validate_password.policy=0;
Query OK, 0 rows affected (0.00 sec)mysql> set global validate_password.length=4;
Query OK, 0 rows affected (0.00 sec)mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)mysql> create user 'mha'@'%' identified with mysql_native_password by 'xxxxxx';
Query OK, 0 rows affected (0.00 sec)

6、配置无密码认证

vim /etc/hosts
192.168.134.132 rabbitmq_1
192.168.134.133 rabbitmq_2
192.168.134.134 slave1、在 master 上配置到所有数据库节点的无密码认证
#前3行每台都要执行 ssh开始找一台执行即可
ssh-keygen -t rsa        #一直回车
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys[root@rabbitmq_1 home]# 
## 到slave1的免密登录#把其他节点得公钥信息写入本地authorized_keys 我是每台机器都执行了执行即可
ssh 192.168.134.133  cat ~/.ssh/id_rsa.pub >>~/.ssh/authorized_keys
ssh 192.168.134.134  cat ~/.ssh/id_rsa.pub >>~/.ssh/authorized_keys
#测试
#在192.168.134.132上
ssh 192.168.134.133
ssh 192.168.134.134
#在192.168.134.133上
ssh 192.168.134.132
ssh 192.168.134.134
#在192.168.134.134上
ssh 192.168.134.132
ssh 192.168.134.133

7、进行检测工作，检测ssh免密和主从，在manager上执行：

[root@rabbitmq_2 conf]# masterha_check_ssh --conf=/home/mha/conf/mysql_mha.cnf
Sat May 13 15:40:18 2023 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Sat May 13 15:40:18 2023 - [info] Reading application default configuration from /home/mha/conf/mysql_mha.cnf..
Sat May 13 15:40:18 2023 - [info] Reading server configuration from /home/mha/conf/mysql_mha.cnf..
Sat May 13 15:40:18 2023 - [info] Starting SSH connection tests..
Sat May 13 15:40:19 2023 - [debug] 
Sat May 13 15:40:18 2023 - [debug]  Connecting via SSH from root@192.168.134.132(192.168.134.132:22) to root@192.168.134.134(192.168.134.134:22)..
Sat May 13 15:40:18 2023 - [debug]   ok.
Sat May 13 15:40:20 2023 - [debug] 
Sat May 13 15:40:18 2023 - [debug]  Connecting via SSH from root@192.168.134.134(192.168.134.134:22) to root@192.168.134.132(192.168.134.132:22)..
Sat May 13 15:40:19 2023 - [debug]   ok.
Sat May 13 15:40:20 2023 - [info] All SSH connection tests passed successfully.[root@rabbitmq_2 bin]# masterha_check_repl --conf=/home/mha/conf/mysql_mha.cnfMySQL Replication Health is OK.
就说明检测没问题

8、检测没问题就在master主节点上手动配置VIP

#配置VIP
[root@rabbitmq_1 bin]# ifconfig ens33:1 192.168.134.100
#查看配置
[root@rabbitmq_1 bin]# ifconfig
#删除VIP
[root@rabbitmq_1 bin]# ifconfig ens33:1 del 192.168.134.100

9、检测没有报错，就可以在manager上启动MHA

启动
[root@rabbitmq_2 log]# nohup masterha_manager --conf=/home/mha/conf/mysql_mha.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /home/mha/log/manager.log 2>&1 &
[1] 12544
#或者
[root@rabbitmq_2 conf]# nohup masterha_manager --conf=/home/mha/conf/mysql_mha.cnf &> /home/mha/log/manager.log &
[1] 3897--conf=/home/mha/conf/mysql_mha.cnf    #指定配置文件
--ignore_last_failover                 #就是当有节点宕掉时，也能启动MHA
--remove_dead_master_conf              #当master服务器失效时，发生主从切换后，会把旧的master的ip从主配置文件删
</dev/null>                            #生成的所有信息会导到nul1下或者/var/log/masterha/app1/manager.log日志文件中
2>&1&                                  #把2错误性的输出 重定向为标准性输山，"&"开启后台运行查看日志
Checking the Status of the script.. OK 
Sat May 13 17:11:57 2023 - [info]  OK.
Sat May 13 17:11:57 2023 - [warning] shutdown_script is not defined.
Sat May 13 17:11:57 2023 - [info] Set master ping interval 1 seconds.
Sat May 13 17:11:57 2023 - [info] Set secondary check script: /usr/bin/masterha_secondary_check -s 192.168.134.133 -s 192.168.134.134
Sat May 13 17:11:57 2023 - [info] Starting ping health check on 192.168.134.132(192.168.134.132:3306)..
Sat May 13 17:11:57 2023 - [info] Ping(SELECT) succeeded, waiting until MySQL doesn't respond..查看MHA状态
[root@rabbitmq_2 log]# masterha_check_status --conf=/home/mha/conf/mysql_mha.cnf
mysql_mha (pid:12544) is running(0:PING_OK), master:192.168.134.132关闭
[root@rabbitmq_2 log]# masterha_stop --conf=/home/mha/conf/mysql_mha.cnf 
Stopped mysql_mha successfully.
[1]+  退出 1                nohup masterha_manager --conf=/home/mha/conf/mysql_mha.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /home/mha/log/manager.log 2>&1
[root@rabbitmq_2 log]#

三、故障模拟测试

故障切换备选主库的算法：

1、一般判断从库的是从（position/GTID）判断优劣，数据有差异，最接近于master的slave，成为备选主。

2、数据一致的情况下，按照配置文件顺序，选择备选主库。

3、设定有权重（candidate_master=1），按照权重强制指定备选主。

默认情况下如果一个slave落后master 100M的relay logs的话，即使有权重，也会失效。

如果check_repl_delay=0的话，即使落后很多日志，也强制选择其为备选主。

#测试

1、先在manager上监控日志

[root@rabbitmq_2 log]# tail -f manager.log

2、在master停掉MySQL服务，观察manager的日志

[root@rabbitmq_1 bin]# systemctl stop mysqld.service

3、在master上可以看到虚拟的VIP,已经消失，查看从节点，可以看到VIP，如下图

4、查看manager日志


----- Failover Report -----mysql_mha: MySQL Master failover 192.168.134.132(192.168.134.132:3306) to 192.168.134.134(192.168.134.134:3306) succeeded#这句话意思是  Master 宕掉了      Master 192.168.134.132(192.168.134.132:3306) is down!Check MHA Manager logs at rabbitmq_2:/home/mha/log/manager.log for details.Started automated(non-interactive) failover.
Invalidated master IP address on 192.168.134.132(192.168.134.132:3306)
The latest slave 192.168.134.134(192.168.134.134:3306) has all relay logs for recovery.#这个为新的Master
Selected 192.168.134.134(192.168.134.134:3306) as a new master.
192.168.134.134(192.168.134.134:3306): OK: Applying all logs succeeded.
192.168.134.134(192.168.134.134:3306): OK: Activated master IP address.
Generating relay diff files from the latest slave succeeded.
192.168.134.134(192.168.134.134:3306): Resetting slave info succeeded.
Master failover to 192.168.134.134(192.168.134.134:3306) completed successfully.

5、MHA发生切换之后

在工作目录会生成一个成功或者失败的标记 mysql_mha.failover.complete

下一次要启动mha之前要把这些标记文件删除，否则mha无法正常启动，因为有了这些标记文件，mha认为已经切换结束
[root@rabbitmq_2 mha]# ls
bin  conf  log  mysql_mha.failover.complete

四、将宕机的MySQL，恢复为master

在线切换时 vip 的管理的脚本（可选）

#!/usr/bin/env perluse strict;
use warnings FATAL => 'all';use Getopt::Long;
use MHA::DBHelper;
use MHA::NodeUtil;
use Time::HiRes qw( sleep gettimeofday tv_interval );
use Data::Dumper;my $_tstart;
my $_running_interval = 0.1;
my ($command,$orig_master_is_new_slave, $orig_master_host, $orig_master_ip,  $orig_master_port, $orig_master_user,    $orig_master_password, $orig_master_ssh_user,$new_master_host,          $new_master_ip,    $new_master_port, $new_master_user,  $new_master_password, $new_master_ssh_user,
);my $vip = '192.168.134.100';
my $brdc = '192.168.134.255';
my $ifdev = 'ens33';
my $key = '1';
my $ssh_start_vip = "/usr/sbin/ip addr add $vip/24 brd $brdc dev $ifdev label $ifdev:$key;/usr/sbin/arping -q -A -c 1 -I $ifdev $vip;iptables -F;";
my $ssh_stop_vip = "/usr/sbin/ip addr del $vip/24 dev $ifdev label $ifdev:$key";GetOptions('command=s'                => \$command,'orig_master_is_new_slave' => \$orig_master_is_new_slave,'orig_master_host=s'       => \$orig_master_host,'orig_master_ip=s'         => \$orig_master_ip,'orig_master_port=i'       => \$orig_master_port,'orig_master_user=s'       => \$orig_master_user,'orig_master_password=s'   => \$orig_master_password,'orig_master_ssh_user=s'   => \$orig_master_ssh_user,'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,'new_master_ssh_user=s'    => \$new_master_ssh_user,
);exit &main();sub current_time_us {my ( $sec, $microsec ) = gettimeofday();my $curdate = localtime($sec);return $curdate . " " . sprintf( "%06d", $microsec );
}sub sleep_until {my $elapsed = tv_interval($_tstart);if ( $_running_interval > $elapsed ) {sleep( $_running_interval - $elapsed );}
}sub get_threads_util {my $dbh                    = shift;my $my_connection_id       = shift;my $running_time_threshold = shift;my $type                   = shift;$running_time_threshold = 0 unless ($running_time_threshold);$type                   = 0 unless ($type);my @threads;my $sth = $dbh->prepare("SHOW PROCESSLIST");$sth->execute();while ( my $ref = $sth->fetchrow_hashref() ) {my $id         = $ref->{Id};my $user       = $ref->{User};my $host       = $ref->{Host};my $command    = $ref->{Command};my $state      = $ref->{State};my $query_time = $ref->{Time};my $info       = $ref->{Info};$info =~ s/^\s*(.*?)\s*$/$1/ if defined($info);next if ( $my_connection_id == $id );next if ( defined($query_time) && $query_time < $running_time_threshold );next if ( defined($command)    && $command eq "Binlog Dump" );next if ( defined($user)       && $user eq "system user" );nextif ( defined($command)&& $command eq "Sleep"&& defined($query_time)&& $query_time >= 1 );if ( $type >= 1 ) {next if ( defined($command) && $command eq "Sleep" );next if ( defined($command) && $command eq "Connect" );}if ( $type >= 2 ) {next if ( defined($info) && $info =~ m/^select/i );next if ( defined($info) && $info =~ m/^show/i );}push @threads, $ref;}return @threads;
}sub main {if ( $command eq "stop" ) {## Gracefully killing connections on the current master# 1. Set read_only= 1 on the new master# 2. DROP USER so that no app user can establish new connections# 3. Set read_only= 1 on the current master# 4. Kill current queries# * Any database access failure will result in script die.my $exit_code = 1;eval {## Setting read_only=1 on the new master (to avoid accident)my $new_master_handler = new MHA::DBHelper();# args: hostname, port, user, password, raise_error(die_on_error)_or_not$new_master_handler->connect( $new_master_ip, $new_master_port,$new_master_user, $new_master_password, 1 );print current_time_us() . " Set read_only on the new master.. ";$new_master_handler->enable_read_only();if ( $new_master_handler->is_read_only() ) {print "ok.\n";}else {die "Failed!\n";}$new_master_handler->disconnect();# Connecting to the orig master, die if any database error happensmy $orig_master_handler = new MHA::DBHelper();$orig_master_handler->connect( $orig_master_ip, $orig_master_port,$orig_master_user, $orig_master_password, 1 );## Drop application user so that nobody can connect. Disabling per-session binlog beforehand#$orig_master_handler->disable_log_bin_local();#print current_time_us() . " Drpping app user on the orig master..\n";#FIXME_xxx_drop_app_user($orig_master_handler);## Waiting for N * 100 milliseconds so that current connections can exitmy $time_until_read_only = 15;$_tstart = [gettimeofday];my @threads = get_threads_util( $orig_master_handler->{dbh},$orig_master_handler->{connection_id} );while ( $time_until_read_only > 0 && $#threads >= 0 ) {if ( $time_until_read_only % 5 == 0 ) {printf
"%s Waiting all running %d threads are disconnected.. (max %d milliseconds)\n",current_time_us(), $#threads + 1, $time_until_read_only * 100;if ( $#threads < 5 ) {print Data::Dumper->new( [$_] )->Indent(0)->Terse(1)->Dump . "\n"foreach (@threads);}}sleep_until();$_tstart = [gettimeofday];$time_until_read_only--;@threads = get_threads_util( $orig_master_handler->{dbh},$orig_master_handler->{connection_id} );}## Setting read_only=1 on the current master so that nobody(except SUPER) can writeprint current_time_us() . " Set read_only=1 on the orig master.. ";$orig_master_handler->enable_read_only();if ( $orig_master_handler->is_read_only() ) {print "ok.\n";}else {die "Failed!\n";}## Waiting for M * 100 milliseconds so that current update queries can completemy $time_until_kill_threads = 5;@threads = get_threads_util( $orig_master_handler->{dbh},$orig_master_handler->{connection_id} );while ( $time_until_kill_threads > 0 && $#threads >= 0 ) {if ( $time_until_kill_threads % 5 == 0 ) {printf
"%s Waiting all running %d queries are disconnected.. (max %d milliseconds)\n",current_time_us(), $#threads + 1, $time_until_kill_threads * 100;if ( $#threads < 5 ) {print Data::Dumper->new( [$_] )->Indent(0)->Terse(1)->Dump . "\n"foreach (@threads);}}sleep_until();$_tstart = [gettimeofday];$time_until_kill_threads--;@threads = get_threads_util( $orig_master_handler->{dbh},$orig_master_handler->{connection_id} );}print "Disabling the VIP on old master: $orig_master_host \n";&stop_vip();     ## Terminating all threadsprint current_time_us() . " Killing all application threads..\n";$orig_master_handler->kill_threads(@threads) if ( $#threads >= 0 );print current_time_us() . " done.\n";#$orig_master_handler->enable_log_bin_local();$orig_master_handler->disconnect();## After finishing the script, MHA executes FLUSH TABLES WITH READ LOCK$exit_code = 0;};if ($@) {warn "Got Error: $@\n";exit $exit_code;}exit $exit_code;}elsif ( $command eq "start" ) {## Activating master ip on the new master# 1. Create app user with write privileges# 2. Moving backup script if needed# 3. Register new master's ip to the catalog database# We don't return error even though activating updatable accounts/ip failed so that we don't interrupt slaves' recovery.
# If exit code is 0 or 10, MHA does not abortmy $exit_code = 10;eval {my $new_master_handler = new MHA::DBHelper();# args: hostname, port, user, password, raise_error_or_not$new_master_handler->connect( $new_master_ip, $new_master_port,$new_master_user, $new_master_password, 1 );## Set read_only=0 on the new master#$new_master_handler->disable_log_bin_local();print current_time_us() . " Set read_only=0 on the new master.\n";$new_master_handler->disable_read_only();## Creating an app user on the new master#print current_time_us() . " Creating app user on the new master..\n";#FIXME_xxx_create_app_user($new_master_handler);#$new_master_handler->enable_log_bin_local();$new_master_handler->disconnect();## Update master ip on the catalog database, etcprint "Enabling the VIP - $vip on the new master - $new_master_host \n";&start_vip();$exit_code = 0;};if ($@) {warn "Got Error: $@\n";exit $exit_code;}exit $exit_code;}elsif ( $command eq "status" ) {# do nothingexit 0;}else {&usage();exit 1;}
}# A simple system call that enable the VIP on the new master 
sub start_vip() {`ssh $new_master_ssh_user\@$new_master_host \" $ssh_start_vip \"`;
}
# A simple system call that disable the VIP on the old_master
sub stop_vip() {`ssh $orig_master_ssh_user\@$orig_master_host \" $ssh_stop_vip \"`;
}sub usage {print
"Usage: master_ip_online_change --command=start|stop|status --orig_master_host=host --orig_master_ip=ip --orig_master_port=port --orig_master_user=user --orig_master_password=password --orig_master_ssh_user=sshuser --new_master_host=host --new_master_ip=ip --new_master_port=port --new_master_user=user --new_master_password=password --new_master_ssh_user=sshuser \n";die;
}

因故障切换后发送报警的脚本（可选）

vim send_mail#!/bin/bash
# 脚本的日志文件
LOGFILE="/home/mha/log/email.log"
:>"$LOGFILE"
exec 1>"$LOGFILE"
exec 2>&1
SMTP_server='smtp.123.com'
username='123@456.com'
password='111*'
from_email_address='123@456.com'
to_email_address='***@***,***@***'message_subject_utf8="MHA集群主库故障转移提醒"HTML_PATH=html_path
echo "<h2 style="color:red">">$HTML_PATH
echo "MHA集群主节点发生故障，进行节点故障转移，请及时解决查看！！！">>$HTML_PATH
echo "</h2>">>$HTML_PATH
echo "<p>以下为MHA集群的相关信息:</p>">>$HTML_PATH
echo "<table border="1" cellspacing="0"  width="700"><tr><th>节点</th><th>角色</th>     <th>作用</th></tr><tr><td>10.6.110.170</td><td>MHA manager</td> <td>MHA监控节点</td></tr><tr><td>10.8.40.77</td><td>master/master.bak</td>      <td>主库或者主备</td></tr><tr><td>10.8.40.68</td><td>master/master.bak</td>     <td>主库或者主备</td></tr><tr><td>10.6.119.241</td><td>slave</td>       <td>从库</td></tr><tr><td>10.8.40.79</td><td>VIP</td>   <td>虚拟ip</td></tr></table>">>$HTML_PATHecho "<br>">>$HTML_PATH
echo "<h4>详细错误日志路径为:10.6.110.170:/data1/mysql_mha/manager.log</h4>">>$HTML_PATHmessage_body_utf8=$(cat $HTML_PATH)#message_body_utf8="mysql的MHA集群主节点发生故障，进行节点故障转移，请及时解决查看！！！"
# 转换邮件标题为GB2312，解决邮件标题含有中文，收到邮件显示乱码的问题。
message_subject_gb2312=`iconv -t GB2312 -f UTF-8 << EOF
$message_subject_utf8
EOF`
[ $? -eq 0 ] && message_subject="$message_subject_gb2312" || message_subject="$message_subject_utf8"
# 转换邮件内容为GB2312，解决收到邮件内容乱码
message_body_gb2312=`iconv -t GB2312 -f UTF-8 << EOF
$message_body_utf8
EOF`
[ $? -eq 0 ] && message_body="$message_body_gb2312" || message_body="$message_body_utf8"
# 发送邮件
sendEmail='/usr/bin/sendEmail'
set -x
$sendEmail -s "$SMTP_server" -xu "$username" -xp "$password" -f "$from_email_address" -t "$to_email_address" -u "$message_subject" -m "$message_body" -o message-content-type=html -o message-charset=gb2312
#同时配置了企业微信通知
sh  /data1/mysql_mha/send_wechat

两个脚本修改完都需要授权可执行文件。

1、先将mysql1设置成master（mysql2）的从服务器，设置只读

mysql> CHANGE MASTER TO MASTER_HOST='192.168.134.134',MASTER_PORT=3306,MASTER_LOG_FILE='mysql-bin.000006',MASTER_LOG_POS=155, MASTER_USER='repl',MASTER_PASSWORD='123456';
mysql> start slave;
设置为只读
mysql>  set global read_only=1;

2、关掉当前master（mysql2）的同步功能，否则从服务器会报错

mysql> stop slave;
mysql> reset slave;

3、手动修改manager上的app1.cnf配置

将刚刚手动宕机 Mysql1 库作为主库继续提供服务，注意手动切换 VIP 不会漂移。重新检查数据库主从状态是否正常
[server1]
hostname=192.168.134.132
port=3306
candidate_master=1
check_repl_delay=0

4、检查无密码认证和 MySQL 主从状态是否正常，启动MHA

nohup masterha_manager --conf=/home/mha/conf/mysql_mha.cnf &> /home/mha/log/manager.log &

5、查看当前主库master

[root@rabbitmq_2 mha]# masterha_check_status --conf=/home/mha/conf/mysql_mha.cnf
mysql_mha (pid:6045) is running(0:PING_OK), master:192.168.134.134

6、关闭MHA

[root@rabbitmq_2 mha]# masterha_stop --conf=/home/mha/conf/mysql_mha.cnf 
Stopped mysql_mha successfully.

7、在manager上手动关闭当前master

[root@rabbitmq_2 mha]# masterha_master_switch --conf=/home/mha/conf/mysql_mha.cnf --master_state=dead --dead_master_host=192.168.134.134可能会报错，目前不知道咋回事，可以检查下master的状态  是否已经停掉了
[root@rabbitmq_2 bin]# masterha_check_status --conf=/home/mha/conf/mysql_mha.cnf
mysql_mha is stopped(2:NOT_RUNNING).

8、在manager上手动设置新的master

[root@rabbitmq_2 bin]#  masterha_master_switch --conf=/home/mha/conf/mysql_mha.cnf --master_state=alive --new_master_host=192.168.134.132 --orig_master_is_new_slave
会提示你让你输入yes
Wed May 17 17:55:58 2023 - [info] * Switching slaves in parallel..
Wed May 17 17:55:58 2023 - [info] 
Wed May 17 17:55:58 2023 - [info] Unlocking all tables on the orig master:
Wed May 17 17:55:58 2023 - [info] Executing UNLOCK TABLES..
Wed May 17 17:55:58 2023 - [info]  ok.
Wed May 17 17:55:58 2023 - [info] Starting orig master as a new slave..
Wed May 17 17:55:58 2023 - [info]  Resetting slave 192.168.134.134(192.168.134.134:3306) and starting replication from the new master 192.168.134.132(192.168.134.132:3306)..
Wed May 17 17:55:58 2023 - [info]  Executed CHANGE MASTER.
Wed May 17 17:55:58 2023 - [info]  Slave started.
Wed May 17 17:55:58 2023 - [info] All new slave servers switched successfully.
Wed May 17 17:55:58 2023 - [info] 
Wed May 17 17:55:58 2023 - [info] * Phase 5: New master cleanup phase..
Wed May 17 17:55:58 2023 - [info] 
Wed May 17 17:55:58 2023 - [info]  192.168.134.132: Resetting slave info succeeded.
Wed May 17 17:55:58 2023 - [info] Switching master to 192.168.134.132(192.168.134.132:3306) completed successfully.

9、启动MHA

10、检查状态看看master是否切换成功

五、遇到的问题

1、

执行masterha_check_repl --conf=/home/mha/conf/mysql_mha.cnf出现问题

解决：

Sat May 13 16:14:10 2023 - [error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln427] Error happened on checking configurations. Can't exec "/home/mha/bin/master_ip_failover": 没有那个文件或目录 at /usr/share/perl5/vendor_perl/MHA/ManagerUtil.pm line 68.
Sat May 13 16:14:10 2023 - [error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln525] Error happened on monitoring servers.
Sat May 13 16:14:10 2023 - [info] Got exit code 1 (Not master dead).
解决：我在创建脚本时候加了.sh   配置文件没加，检测时候找不到脚本

2、

执行masterha_check_ssh --conf=/home/mha/conf/mysql_mha.cnf出现问题

Fri Feb 19 14:41:24 2021 - [error][/usr/share/perl5/vendor_perl/MHA/SSHCheck.pm, ln63]
Fri Feb 19 14:41:23 2021 - [debug]  Connecting via SSH from root@10.8.40.77(10.8.40.77:22) to sysadm@10.6.119.241(10.6.119.241:22)..
Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
Fri Feb 19 14:41:24 2021 - [error][/usr/share/perl5/vendor_perl/MHA/SSHCheck.pm, ln111] SSH connection from root@10.8.40.77(10.8.40.77:22) to sysadm@10.6.119.241(10.6.119.241:22) failed!
Fri Feb 19 14:41:25 2021 - [debug]解决：
是因为mha的manager和slave在一台机器上，所以/etc/mha/mysql_mha.cnf最后一个注释掉，即把与manager在一台机器上的[server3]注释即可

3、启动MHA时报错

[root@rabbitmq_2 log]# nohup masterha_manager --conf=/home/mha/conf/mysql_mha.cnf &> /home/mha/log/manager.log
Sat May 13 16:52:45 2023 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Sat May 13 16:52:45 2023 - [info] Reading application default configuration from /home/mha/conf/mysql_mha.cnf..
Sat May 13 16:52:45 2023 - [info] Reading server configuration from /home/mha/conf/mysql_mha.cnf..
Cannot write to '/var/home/mha/log/manager.log': 没有那个文件或目录 at /usr/share/perl5/vendor_perl/Log/Dispatch/File.pm line 109.解决：
是因为我的日志文件路径写错了，修改路径即可

4、当主库挂了 MHA日志报错

解决：

是因为我配置文件中，检查节点IP 指向了MHA Manager的IP 所以报这个错误，把地址改了就可以了。

5、

报错mysqlbinlog 错误（此图引用其他博主内容，我的报错忘了留存）

解决办法：（所有节点）做软连接

[root@node2 ~]# which mysqlbinlog
/usr/local/mysql/bin/mysqlbinlog
[root@node2 ~]# ln -s /usr/local/mysql/bin/mysqlbinlog /usr/bin/mysqlbinlog[root@node2 ~]# which mysql/usr/local/mysql/bin/mysql
[root@node2 ~]# ln -s /usr/local/mysql/bin/mysql /usr/local/bin/mysql

6、

报错：[/usr/share/perl5/vendor_perl/MHA/ServerManager.pm, ln492] Server 192.168.134.133(192.168.134.133:3306) is dead, but must be alive! Check server settings.

解决：

1、#删除MHA管理机上的这个文件
[root@centos7-04 ~]# rm -rf /home/mha/app1.failover.complete 
2、关闭防火墙
3、重启master的服务