介绍：
Maxscale是mariadb开发的一个MySQL数据中间件，配置简单，能够实现读写分离，并且能根据主从状态实现写库的自动切换，对多个服务器实现负载均衡。
实验环境：
基于gtid的主从同步的基础上进行配置
| 中间件 | 192.168.93.20 | MaxScale 24.02.5 | Rocky8 |
| 主服务器 | 192.168.93.10 | Mysql 8.0.41 | openEuler |
| 从服务器 | 192.168.93.11 | Mysql 8.0.41 | openEluer |
| 从服务器 | 192.168.93.12 | Mysql 8.0.41 | openEuler |
配置：
1、安装maxscale
下载的话可以先配置maxscale的yum源：/etc/yum.repos.d/mariadb.repo
[mariadb-main]
name = MariaDB Server
baseurl = https://dlm.mariadb.com/repo/mariadb-server/11.rolling/yum/rhel/8/x86_64
gpgkey = file:///etc/pki/rpm-gpg/MariaDB-Server-GPG-KEY
gpgcheck = 1
enabled = 1
module_hotfixes = 1
[mariadb-maxscale]
# To use the latest stable release of MaxScale, use "latest" as the version
# To use the latest beta (or stable if no current beta) release of MaxScale, use "beta" as the version
name = MariaDB MaxScale
baseurl = https://dlm.mariadb.com/repo/maxscale/latest/yum/rhel/8/x86_64
gpgkey = file:///etc/pki/rpm-gpg/MariaDB-MaxScale-GPG-KEY
gpgcheck = 1
enabled = 1
[mariadb-tools]
name = MariaDB Tools
baseurl = https://downloads.mariadb.com/Tools/rhel/8/x86_64
gpgkey = file:///etc/pki/rpm-gpg/MariaDB-Enterprise-GPG-KEY
gpgcheck = 1
enabled = 1
官方文档上给了脚本的方式配置：
https://mariadb.com/kb/en/library/mariadb-package-repository-setup-and-usage/
curl -LsS https://r.mariadb.com/downloads/mariadb_repo_setup | sudo bash
查看是否又安装包：
[root@Rocky-1 ~]# dnf install maxscale.x86_64
2、配置
安装完成之后会有一个主配置文件/etc/maxscal.cnf，也可在其子配置文件下配置，注意以.cnf结尾
[maxscale]
#开启线程个数，默认为1，设置auto会同cpu核数相同
threads=auto[dbserver1]
type=server
address=192.168.93.10
port=3306
protocol=MariaDBBackend[dbserver2]
type=server
address=192.168.93.11
port=3306
protocol=MariaDBBackend[dbserver3]
type=server
address=192.168.93.12
port=3306
protocol=MariaDBBackend[MySQL-Monitor]
#监视进程
type=monitor
module=mariadbmon
servers=dbserver1,dbserver2,dbserver3
user=maxscale_monitor
password=Admin@123456
monitor_interval=2s[Read-Write-Service]
读写分离
type=service
router=readwritesplit
servers=dbserver1,dbserver2,dbserver3
user=maxscale_route
password=Admin@123456
enable_root_user=true[Read-Write-Listenner]
#监听读写端口
type=listener
service=Read-Write-Service
protocol=MariaDBClient
address=0.0.0.0
port=3306
3、创建用户
创建监控用户：
mysql> create user 'maxscale_monitor'@'192.168.93.%' identified with mysql_native_password by 'Admin@123456';
mysql> grant replication slave, replication client on *.* to maxscale_monitor@'192.168.93.%';
创建路由用户：
create user 'maxscale_route'@'192.168.93.%' identified with mysql_native_password by 'Admin@123456';
GRANT SHOW DATABASES ON *.* TO maxscale_route@'192.168.93.%';
GRANT SELECT ON mysql.user TO maxscale_route@'192.168.93.%';
GRANT SELECT ON mysql.db TO maxscale_route@'192.168.93.%';
GRANT SELECT ON mysql.tables_priv TO maxscale_route@'192.168.93.%';
GRANT SELECT ON mysql.columns_priv TO maxscale_route@'192.168.93.%';
GRANT SELECT ON mysql.proxies_priv TO maxscale_route@'192.168.93.%';
配置完成重启服务：
[root@Rocky-1 ~]# maxscale -f /etc/maxscale.cnf.d/maxscale.cnf -U maxscale
#查看端口的监听状态[root@Rocky-1 ~]# ps -ef | grep maxscale
maxscale 10908 1 0 23:23 ? 00:00:00 maxscale -f /etc/maxscale.cnf.d/maxscale.cnf -U maxscale
root 10921 1619 0 23:25 pts/0 00:00:00 grep --color=auto maxscale
查看运行状态，注册服务，服务监听状态信息
测试
在master上创建一个访问用，已经实现主从复制的前提下，主库创建的用户能同步到从库上
create user 'admin_user'@'%' identified with mysql_native_password by 'Admin@123456';
grant all privileges on *.* to 'admin_user'@'%' with grant option;
#测试连接
主库创建一个数据库，从库马上更新，实验完成！
