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ProxySQL实现MySQL读写分离

ProxySQL是一个读写分离的中间件,开源项目,优势是强大的规则引擎、支持在线配置、支持负载均衡,详情可以参考官方文档
ProxySQL还支持prepare、query cache、连接池,这些特性不在本文的介绍范围内
这里需要说明一下,读写分离方案是要看实际场景的。
如果对数据实时性要求极高,例如订单系统,是不适合读写分离方案的,因为读数据节点同步写数据节点的数据是有一定时间差的。
当然也不是就不能用,只是针对这种场景需要单独设置此时读数据和写数据使用同一节点

下面介绍一下ProxySQL的安装和配置。

说明一下服务器情况:

1. 一共三台服务器,系统ubuntu16.04 64位
2. IP分别为:192.168.1.222、192.168.1.223、192.168.1.224,均安装了MySQL5.7
3. 222为master节点,223和224都是slave节点
4. mha-manager装在223上,三台机器都装了mha-node

ProxySQL安装

下载安装包

wget https://github.com/sysown/proxysql/releases/download/v1.4.9/proxysql_1.4.9-dbg-ubuntu16_amd64.deb

安装

dpkg -i proxysql_1.4.9-dbg-ubuntu16_amd64.deb

启动服务

service proxysql start

ProxySQL配置

ProxySQL的配置是支持两种方式的:配置文件,数据库。

数据库的配置方式在第一次启动服务的时候也是基于配置文件的(/etc/proxysql.cnf),后续所有的配置都是在SQLLite中进行,并且不会更新proxysql.cnf配置文件,配置是存储在/var/lib/proxysql/proxysql.db中。

前面提到的在线配置就是基于数据库的,所以这里我们就讲解在数据库中的配置方式。

1. 创建服务账号和monitor账号

登录master数据库

mysql mysql -u root -p

添加账号并授权

GRANT ALL ON *.* TO 'proxysql'@'192.168.1.%' IDENTIFIED BY 'proxysql';
GRANT SELECT ON *.* TO 'monitor'@'192.168.1.%' IDENTIFIED BY 'monitor';

要先创建两个数据库账号用于后续配置,其中proxysql用于操作数据库,monitor用于监控。

2. 登录到proxysql管理端

proxysql管理端口默认是6032,默认的用户名密码都是admin。

mysql -uadmin -padmin -h127.0.0.1 -P6032

3. 查看数据库信息

mysql> 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 |
| 6   | myhgm         |                                     |
+-----+---------------+-------------------------------------+
6 rows in set (0.00 sec)
main:默认数据库,存放用户验证、路由规则等信息。我们要做的配置都是针对这个库的;
disk:持久化到硬盘的配置;
stats:proxysql运行抓取的统计信息,如各命令的执行次数、查询执行时间等;
monitor:monitor模块收集的信息,db的健康情况、各种检查等。

4. 查看配置表

mysql> show tables;
+--------------------------------------------+
| tables                                     |
+--------------------------------------------+
| debug_levels                               |
| 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                                  |
+--------------------------------------------+
21 rows in set (0.00 sec)
global_variables:各种变量,包括监听的端口、管理账号、是否禁用monitor等,详情可以参考[官方文档](https://github.com/sysown/proxysql/wiki/Global-variables);
mysql_*:mysql开头的表就是我们配置要操作的表,具体都是干什么的还是看官方文档吧,介绍的很细,后面我会针对读写分离的配置做介绍;
runtime_*:runtime开头的表是运行时读的表,不能通过DML语句修改,我们针对mysql开头的表做完配置修改之后,要执行**load mysql xxx to runtime**以将对应的配置加载到运行时环境。
注意:当执行完load语句将配置加载到运行时环境后,还要执行**save mysql xxx to disk**将配置存到硬盘上,以便下次重启时加载,如果忘记执行,当重启时本次修改的配置会丢失。

5. 添加DB实例

我们一共有三个节点(一个master两个slave),要进行读写分离,这里我们将master设为写节点,两个slave设为读节点。

mysql> insert into mysql_servers(hostgroup_id,hostname,port,weight,max_connections,max_replication_lag,comment) values(1000,'192.168.1.222',3306,1,1000,10,'write group');
Query OK, 1 row affected (0.00 sec)

mysql> insert into mysql_servers(hostgroup_id,hostname,port,weight,max_connections,max_replication_lag,comment) values(2000,'192.168.1.223',3306,1,1000,10,'read group');
Query OK, 1 row affected (0.00 sec)

mysql> insert into mysql_servers(hostgroup_id,hostname,port,weight,max_connections,max_replication_lag,comment) values(2000,'192.168.1.224',3306,1,1000,10,'read group');
Query OK, 1 row affected (0.00 sec)

mysql> select * from mysql_servers;
+--------------+---------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-------------+
| hostgroup_id | hostname      | port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment     |
+--------------+---------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-------------+
| 1000         | 192.168.1.222 | 3306 | ONLINE | 1      | 0           | 1000            | 10                  | 0       | 0              | write group |
| 2000         | 192.168.1.223 | 3306 | ONLINE | 1      | 0           | 1000            | 10                  | 0       | 0              | read group  |
| 2000         | 192.168.1.224 | 3306 | ONLINE | 1      | 0           | 1000            | 10                  | 0       | 0              | read group  |
+--------------+---------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-------------+
3 rows in set (0.00 sec)
hostgroup_id:一个角色一个id,该表的主键是hostgroup_id+hostname+port
hostname:db实例IP
port:db实例端口
weight:权重,如果有多个相同角色的实例,会优先选择权重高的
status:状态
    -ONLINE 正常
    -SHUNNED 临时被剔除
    -OFFLINE_SOFT 软离线状态,不再接受新的连接,已建立的连接会等待
    -OFFLINE_HARD 离线,不接收新连接, 已建立的连接也会强制断开(宕机或者网络不可用)
max_connections:最大连接数
max_replication_lag:允许的最大延迟

6. 添加服务账号

mysql> INSERT INTO mysql_users(username,password,default_hostgroup) VALUES ('proxysql','proxysql',1000);
Query OK, 1 row affected (0.01 sec)

mysql> select * from mysql_users;
+----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+
| username | password | active | use_ssl | default_hostgroup | default_schema | schema_locked | transaction_persistent | fast_forward | backend | frontend | max_connections |
+----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+
| proxysql | proxysql | 1      | 0       | 1000              | NULL           | 0             | 1                      | 0            | 1       | 1        | 10000           |
+----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+
1 row in set (0.01 sec)

7. 设置监控账号

mysql> set mysql-monitor_username='monitor';
Query OK, 1 row affected (0.00 sec)

mysql> set mysql-monitor_password='monitor';
Query OK, 1 row affected (0.00 sec)

8. 添加规则

读写分离规则

mysql> insert into mysql_query_rules(rule_id,active,match_digest,destination_hostgroup,apply)values(1,1,'^SELECT.*FOR UPDATE$',1000,1);
Query OK, 1 row affected (0.00 sec)

mysql> insert into mysql_query_rules(rule_id,active,match_digest,destination_hostgroup,apply)values(2,1,'^SELECT',2000,1);
Query OK, 1 row affected (0.00 sec)

mysql> 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$ | 1000                  | 1     |
| 2       | 1      | ^SELECT              | 2000                  | 1     |
+---------+--------+----------------------+-----------------------+-------+
2 rows in set (0.00 sec)

9. 完善配置

我们的mysql集群是基于MHA的,master挂掉之后,slave会提升为新的master,这个时候我们希望proxysql的规则自动变更,在mysql_servers中增加一条记录,将新的master的hostname和port添加到写的hostgroup中。
proxysql是支撑这种配置的,根据mysql_replication_hostgroups中的数据,proxysql通过检测到各server的read_only值来自动为server设置hostgroup_id
mysql> insert into  mysql_replication_hostgroups (writer_hostgroup,reader_hostgroup,comment) values(1000,2000,'Reading and Writing Separation');
Query OK, 1 row affected (0.00 sec)

mysql> select * from runtime_mysql_replication_hostgroups;
+------------------+------------------+--------------------------------+
| writer_hostgroup | reader_hostgroup | comment                        |
+------------------+------------------+--------------------------------+
| 1000             | 2000             | Reading and Writing Separation |
+------------------+------------------+--------------------------------+
1 row in set (0.01 sec)

10. 将配置加载到运行时

mysql> load mysql users to runtime;
Query OK, 0 rows affected (0.00 sec)

mysql> load mysql servers to runtime;
Query OK, 0 rows affected (0.00 sec)

mysql> load mysql query rules to runtime;
Query OK, 0 rows affected (0.00 sec)

mysql> load mysql variables to runtime;
Query OK, 0 rows affected (0.00 sec)

mysql> load admin variables to runtime;
Query OK, 0 rows affected (0.00 sec)

11. 将配置保存到硬盘

mysql> save mysql users to disk;
Query OK, 0 rows affected (0.15 sec)

mysql> save mysql servers to disk;
Query OK, 0 rows affected (0.33 sec)

mysql> save mysql query rules to disk;
Query OK, 0 rows affected (0.36 sec)

mysql> save mysql variables to disk;
Query OK, 96 rows affected (0.09 sec)

mysql> save admin variables to disk;
Query OK, 32 rows affected (0.09 sec)

到此读写分离的相关配置就大功告成了!之后我们的应用可以通过配置中配置proxysql用户连接proxysql服务操作我们的mysql集群。

mysql -uproxysql -pproxysql -h 127.0.0.1 -P 6033

注:本文转自https://www.jianshu.com/p/121e3196cf29

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