MaxScale：实现MySQL读写分离与负载均衡的中间件利器
目录
- 参考资料: DBAplus 社区
搭建主从集群
安装 MaxScale
yum install https://downloads.mariadb.com/MaxScale/2.5.6/centos/7/x86_64/maxscale-2.5.6-1.rhel.7.x86_64.rpm配置 MaxScale
在主库创建监控用户，路由用户
# 监控账号
create user scalemon@'%' identified by "123456";
grant replication slave, replication client on *.* to scalemon@'%';
# 路由用户
create user maxscale@'%' identified by "123456";
grant select on mysql.* to maxscale@'%';
grant show databases on *.* to maxscale@'%';从库会自动同步账号
开始配置
由于我们只使用 Read-Write-Service，不需要 Read-Only-Service，将其注释即可。 Read-Only-Listener 也需要同时注释
[root@db-proxy ~]# cat /etc/maxscale.cnf
# MaxScale documentation:
# https://mariadb.com/kb/en/mariadb-maxscale-24/
# Global parameters
#
# Complete list of configuration options:
# https://mariadb.com/kb/en/mariadb-maxscale-24-mariadb-maxscale-configuration-guide/
[maxscale]
threads=auto
log_info=1
logdir=/tmp/
admin_host=0.0.0.0
admin_secure_gui=false
# Server definitions
#
# Set the address of the server to the network
# address of a MariaDB server.
#
[server1]
type=server
address=10.10.1.11
port=3306
protocol=MariaDBBackend
[server2]
type=server
address=10.10.1.12
port=3306
protocol=MariaDBBackend
[server3]
type=server
address=10.10.1.13
port=3306
protocol=MariaDBBackend
# Monitor for the servers
#
# This will keep MaxScale aware of the state of the servers.
# MariaDB Monitor documentation:
# https://mariadb.com/kb/en/mariadb-maxscale-24-mariadb-monitor/
[MariaDB-Monitor]
type=monitor
module=mariadbmon
servers=server1,server2,server3
user=scalemon
password=123456
monitor_interval=2000
# Service definitions
#
# Service Definition for a read-only service and
# a read/write splitting service.
#
# ReadConnRoute documentation:
# https://mariadb.com/kb/en/mariadb-maxscale-24-readconnroute/
#[Read-Only-Service]
#type=service
#router=readconnroute
#servers=server1,server2,server3
#user=maxscale
#password=123456
#router_options=slave
# ReadWriteSplit documentation:
# https://mariadb.com/kb/en/mariadb-maxscale-24-readwritesplit/
[Read-Write-Service]
type=service
router=readwritesplit
servers=server1,server2,server3
user=maxscale
password=123456
# Listener definitions for the services
#
# These listeners represent the ports the
# services will listen on.
#
#[Read-Only-Listener]
#type=listener
#service=Read-Only-Service
#protocol=MariaDBClient
#port=4008
[Read-Write-Listener]
type=listener
service=Read-Write-Service
protocol=MariaDBClient
port=4006启动检查状态
[root@db-proxy ~]# systemctl start maxscale.service
[root@MHA_Maxscale ~]# netstat -anptl | grep maxscale
[root@db-proxy ~]# ss -anptl | grep maxscale
LISTEN 0 128 *:8989 *:* users:(("maxscale",pid=1498,fd=23))
LISTEN 0 128 :::4006 :::* users:(("maxscale",pid=1498,fd=28))- 4006: 是 MaxScale 实现 MySQL 读写分离时连接使用的端口
- 8989: 是 MaxScale web 管理页面端口
使用 maxctrl 命令查看数据库连接状态
[root@db-proxy ~]# maxctrl list services
┌────────────────────┬────────────────┬─────────────┬───────────────────┬───────────────────────────┐
│ Service │ Router │ Connections │ Total Connections │ Servers │
├────────────────────┼────────────────┼─────────────┼───────────────────┼───────────────────────────┤
│ Read-Write-Service │ readwritesplit │ 0 │ 0 │ server1, server3, server2 │
└────────────────────┴────────────────┴─────────────┴───────────────────┴───────────────────────────┘
[root@db-proxy ~]# maxctrl list servers
┌─────────┬────────────┬──────┬─────────────┬─────────────────┬──────┐
│ Server │ Address │ Port │ Connections │ State │ GTID │
├─────────┼────────────┼──────┼─────────────┼─────────────────┼──────┤
│ server2 │ 10.10.1.12 │ 3306 │ 0 │ Slave, Running │ │
├─────────┼────────────┼──────┼─────────────┼─────────────────┼──────┤
│ server1 │ 10.10.1.11 │ 3306 │ 0 │ Master, Running │ │
├─────────┼────────────┼──────┼─────────────┼─────────────────┼──────┤
│ server3 │ 10.10.1.13 │ 3306 │ 0 │ Slave, Running │ │
└─────────┴────────────┴──────┴─────────────┴─────────────────┴──────┘也可以登录 Web 页面查看，地址: http://maxscale_server_ip:8989, 默认的用户名和密码是
admin/mariadb
测试读写分离
使用 mysql 命令连接 maxscale 4006 端口进行测试，应用端也是使用此地址和端口进行连接数据库
[root@db-proxy ~]# mysql -h 10.10.1.10 -P 4006 -u lwg -p123456
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.7.28-log MySQL Community Server (GPL)
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MySQL [(none)]> select @@hostname; # 默认读操作会发送至从库，重复多次执行可以看到两台从库轮询的效果
+------------+
| @@hostname |
+------------+
| db2 |
+------------+
1 row in set (0.01 sec)
MySQL [(none)]> begin; select @@hostname; rollback; # 使用开启事务方式，模拟写操作，可以看到写操作被发送到主库
Query OK, 0 rows affected (0.01 sec)
+------------+
| @@hostname |
+------------+
| db1 |
+------------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)