MySQL中间件proxysql实现读写分离

环境说明:

IP	角色	应用	平台
192.168.161.96	读写分离解析主机	proxysql	rhel7.4
192.168.161.164	master	mysql	rhel7.4
192.168.161.167	slave	mysql	rhel7.4

前提要求：

• 关闭防火墙
• 关闭selinux
• 安装MySQL并配置主从

在192.168.161.96上做读写分离解析主机
安装ProxySQL

//配置proxysql的yum源
[root@localhost ~]# cat <<EOF | tee /etc/yum.repos.d/proxysql.repo
> [proxysql_repo]
> name=ProxySQL
> baseurl=http://repo.proxysql.com/ProxySQL/proxysql-1.4.x/centos/7
> gpgcheck=1
> gpgkey=http://repo.proxysql.com/ProxySQL/repo_pub_key
> EOF
[proxysql_repo]
name=ProxySQL
baseurl=http://repo.proxysql.com/ProxySQL/proxysql-1.4.x/centos/7
gpgcheck=1
gpgkey=http://repo.proxysql.com/ProxySQL/repo_pub_key
//安装proxysql
[root@localhost ~]# yum -y install proxysql

//启动proxysql并设置开机自动启动
//proxysql默认只提供了sysv风格的启动脚本，所以想设置开机自启则需借助于chkconfig工具
[root@localhost ~]# systemctl start proxysql
[root@localhost ~]# chkconfig proxysql on

• mysql主库添加proxysql可以增删改查的账号

mysql> grant all on *.* to 'proxysql'@'192.168.161.96' identified by 'pwproxysql'';
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

登录proxysql管理端
安装mariadb

[root@localhost ~]# yum -y install mariadb
[root@localhost ~]# export MYSQL_PS1="(\u@\h:\p) [\d]> "
[root@localhost ~]# mysql -uadmin -padmin -h127.0.0.1 -P6032
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

([email protected]:6032) [(none)]> 
([email protected]:6032) [(none)]> show databases;
+-----+---------------+-------------------------------------+
| seq | name          | file                                |
+-----+---------------+-------------------------------------+
| 0   | main          |                                     |
| 2   | disk          | /var/lib/proxysql/proxysql.db       |
| 3   | stats         |                                     |
| 4   | monitor       |                                     |
| 5   | stats_history | /var/lib/proxysql/proxysql_stats.db |
+-----+---------------+-------------------------------------+
5 rows in set (0.00 sec)

数据库说明：

• main 内存配置数据库，表里存放后端db实例、用户验证、路由规则等信息。表名以 runtime开头的表示proxysql当前运行的配置内容，不能通过dml语句修改，只能修改对应的不以 runtime 开头的（在内存）里的表，然后 LOAD 使其生效， SAVE 使其存到硬盘以供下次重启加载
• disk 是持久化到硬盘的配置，sqlite数据文件
• stats 是proxysql运行抓取的统计信息，包括到后端各命令的执行次数、流量、processlist、查询种类汇总/执行时间等等
• monitor 库存储 monitor 模块收集的信息，主要是对后端db的健康/延迟检查
• stats_history 统计信息历史库

Proxysql管理端添加后端连接mysql主从数据库的配置

([email protected]:6032) [(none)]> show tables from main;
+--------------------------------------------+
| tables                                     |
+--------------------------------------------+
| global_variables                           |
| mysql_collations                           |
| mysql_group_replication_hostgroups         |
| mysql_query_rules                          |
| mysql_query_rules_fast_routing             |
| mysql_replication_hostgroups               |
| mysql_servers                              |
| mysql_users                                |
| proxysql_servers                           |
| runtime_checksums_values                   |
| runtime_global_variables                   |
| runtime_mysql_group_replication_hostgroups |
| runtime_mysql_query_rules                  |
| runtime_mysql_query_rules_fast_routing     |
| runtime_mysql_replication_hostgroups       |
| runtime_mysql_servers                      |
| runtime_mysql_users                        |
| runtime_proxysql_servers                   |
| runtime_scheduler                          |
| scheduler                                  |
+--------------------------------------------+
20 rows in set (0.00 sec)

runtime_ 开头的是运行时的配置，这些是不能修改的。要修改 ProxySQL 的配置，需要修改了非 runtime_ 表，修改后必须执行 LOAD … TO RUNTIME 才能加载到 RUNTIME 生效，执行 save … to disk 才能将配置持久化保存到磁盘

下面语句中没有先切换到 main 库也执行成功了，因为 ProxySQL 内部使用的 SQLite3 数据库引擎，和 MySQL 的解析方式是不一样的。即使执行了 USE main 语句也是无任何效果的，但不会报错

使用 insert 语句添加 mysql 主机到 mysql_servers 表中，其中：hostgroup_id 1 表示写组，2表示读组

([email protected]:6032) [(none)]> insert into mysql_servers(hostgroup_id,hostname,port,weight,comment) values(1,'192.168.161.164',3306,1,'Write Group');
Query OK, 1 row affected (0.00 sec)

([email protected]:6032) [(none)]> insert into mysql_servers(hostgroup_id,hostname,port,weight,comment) values(2,'192.168.161.167',3306,1,'Read Group');
Query OK, 1 row affected (0.00 sec)

([email protected]:6032) [(none)]> select * from mysql_servers;
+--------------+-----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-------------+
| hostgroup_id | hostname        | port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment     |
+--------------+-----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-------------+
| 1            | 192.168.161.164 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              | Write Group |
| 2            | 192.168.161.167 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              | Read Group  |
+--------------+-----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-------------+
2 rows in set (0.00 sec)

修改后，需要加载到RUNTIME，并保存到disk

([email protected]:6032) [(none)]> load mysql servers to runtime;
Query OK, 0 rows affected (0.00 sec)

([email protected]:6032) [(none)]> save mysql servers to disk;
Query OK, 0 rows affected (0.05 sec)

在 proxysql 主机的 mysql_users 表中添加刚才在 master 上创建的账号 proxysql，proxysql 客户端需要使用这个账号来访问数据库
default_hostgroup 默认组设置为写组，也就是1;
当读写分离的路由规则不符合时，会访问默认组的数据库;

([email protected]:6032) [(none)]> insert into mysql_users(username,password,default_hostgroup,transaction_persistent)values('proxysql','pwproxysql',1,1);
Query OK, 1 row affected (0.00 sec)


([email protected]:6032) [(none)]> select * from mysql_users \G
*************************** 1. row ***************************
              username: proxysql
              password: pwproxysql
                active: 1
               use_ssl: 0
     default_hostgroup: 1
        default_schema: NULL
         schema_locked: 0
transaction_persistent: 1
          fast_forward: 0
               backend: 1
              frontend: 1
       max_connections: 10000
1 row in set (0.00 sec)
([email protected]:6032) [(none)]> load mysql users to runtime;
Query OK, 0 rows affected (0.00 sec)

([email protected]:6032) [(none)]> save mysql users to disk;
Query OK, 0 rows affected (0.01 sec)

添加健康检测的帐号
在mysql的 master 端添加属于proxysql的只读账号

mysql> GRANT SELECT ON *.* TO 'monitor'@'192.168.161.%' IDENTIFIED BY 'monitor'; 
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.03 sec)

在proxysql主机端修改变量设置健康检测的账号

([email protected]:6032) [(none)]> set mysql-monitor_username='monitor';
Query OK, 1 row affected (0.01 sec)

([email protected]:6032) [(none)]> set mysql-monitor_password='monitor';
Query OK, 1 row affected (0.00 sec)

([email protected]:6032) [(none)]> load mysql variables to runtime;
Query OK, 0 rows affected (0.00 sec)

([email protected]:6032) [(none)]> save mysql variables to disk;
Query OK, 97 rows affected (0.01 sec)

添加读写分离的路由规则
需求：

• 将 select 查询语句全部路由至 hostgroup_id=2 的组(也就是读组)
• 但是 select * from tb for update 这样的语句是会修改数据的，所以需要单独定义，将它路由至 hostgroup_id=1 的组(也就是写组)
• 其他没有被规则匹配到的组将会被路由至用户默认的组(mysql_users 表中的 default_hostgroup)

([email protected]:6032) [(none)]> insert into mysql_query_rules(rule_id,active,match_digest,destination_hostgroup,apply)values(1,1,'^SELECT.*FOR UPDATE$',1,1);
Query OK, 1 row affected (0.00 sec)

([email protected]:6032) [(none)]> insert into mysql_query_rules(rule_id,active,match_digest,destination_hostgroup,apply)values(2,1,'^SELECT',2,1);
Query OK, 1 row affected (0.00 sec)

([email protected]:6032) [(none)]> select rule_id,active,match_digest,destination_hostgroup,apply from mysql_query_rules;
+---------+--------+----------------------+-----------------------+-------+
| rule_id | active | match_digest         | destination_hostgroup | apply |
+---------+--------+----------------------+-----------------------+-------+
| 1       | 1      | ^SELECT.*FOR UPDATE$ | 1                     | 1     |
| 2       | 1      | ^SELECT              | 2                     | 1     |
+---------+--------+----------------------+-----------------------+-------+
2 rows in set (0.00 sec)

([email protected]:6032) [(none)]> load mysql query rules to runtime;
Query OK, 0 rows affected (0.00 sec)

([email protected]:6032) [(none)]> load admin variables to runtime;
Query OK, 0 rows affected (0.00 sec)

([email protected]:6032) [(none)]> save mysql query rules to disk;
Query OK, 0 rows affected (0.01 sec)

([email protected]:6032) [(none)]> save admin variables to disk;
Query OK, 31 rows affected (0.03 sec)

验证读写分离
登录 proxysql 客户端
登录用户是刚才我们在 mysql_user 表中创建的用户，端口为6033

[root@localhost ~]# mysql -uproxysql -ppwproxysql -h127.0.0.1 -P6033
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.5.30 (ProxySQL)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

([email protected]:6033) [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.05 sec)

尝试修改数据库和查询
创建2个数据库并查询一下表

([email protected]:6033) [(none)]> create database xixi;
Query OK, 1 row affected (0.00 sec)

([email protected]:6033) [(none)]> create database haha;
Query OK, 1 row affected (0.00 sec)

([email protected]:6033) [(none)]> select user,host from mysql.user;
+---------------+----------------+
| user          | host           |
+---------------+----------------+
| monitor       | 192.168.161.%  |
| proxysql      | 192.168.161.96 |
| mysql.session | localhost      |
| mysql.sys     | localhost      |
| root          | localhost      |
+---------------+----------------+
5 rows in set (0.00 sec)

验证读写分离是否成功
proxysql有个类似审计的功能，可以查看各类SQL的执行情况，其需要在proxysql管理端执行

[root@localhost ~]# mysql -uadmin -padmin -h127.0.0.1 -P6032
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

([email protected]:6032) [(none)]> select * from stats_mysql_query_digest;
+-----------+--------------------+----------+--------------------+----------------------------------+------------+------------+------------+----------+----------+----------+
| hostgroup | schemaname         | username | digest             | digest_text                      | count_star | first_seen | last_seen  | sum_time | min_time | max_time |
+-----------+--------------------+----------+--------------------+----------------------------------+------------+------------+------------+----------+----------+----------+
| 1         | information_schema | proxysql | 0xEB4549A4A010C504 | create database haha             | 1          | 1543034576 | 1543034576 | 2522     | 2522     | 2522     |
| 1         | information_schema | proxysql | 0x2C9014AFB3100E16 | create database xixi             | 1          | 1543034570 | 1543034570 | 2132     | 2132     | 2132     |
| 2         | information_schema | proxysql | 0x0F02B330C823D739 | select user,host from mysql.user | 1          | 1543034594 | 1543034594 | 3562     | 3562     | 3562     |
+-----------+--------------------+----------+--------------------+----------------------------------+------------+------------+------------+----------+----------+----------+
6 rows in set (0.00 sec)

从上面的 hostgroup 和 digest_text 值来看，所有的写操作都被路由至1组，读操作都被路由至2组，其中1组为写组，2组为读组！

由此可见，读写分离成功