ProxySQL实现读写分离

环境：

192.168.205.37: as ProxySQL server 
192.168.205.47: as Master server 
192.168.205.57: as Slave server

版本：

OS: centos 7 1810 with mini install 
mariadb-server 5.5.60
proxysql-1.4.15-1-centos7.x86_64.rpm

目地：

proxysql可以实现读写分离，它主要读取数据库的read_only变量来判断那些是主从服务器，当创建读写组时它会跟据状态自动将节点划分到相应的组中，如写组10和读组20，并跟据建立好的规则和对应的组名，从而实现读写的分离操作，proxysql是基于一个轻量级的数据库，所有的设置都要在数据库中进行更改，步聚有点繁琐。

步骤：

1. 使用如下的脚本安将两个数据库

   [root@master data]#cat maridb_yum.sh 
   #!/bin/bash
   ID=`ip a show dev eth0 | sed -r '3!d;s@(.*inet)(.*)(/.*)@\2@' | cut -d. -f4`
   rpm -q mariadb-server ||yum install -y mariadb-server
   [ -d /data/mysql ] || mkdir -p /data/mysql
   [ -d /data/logs ] || mkdir -p /data/logs
   chown mysql:mysql /data/{mysql,logs}
   sed -i 's@datadir=/var/lib/mysql@datadir=/data/mysql@' /etc/my.cnf
   grep "log-bin" /etc/my.cnf || sed -i '/\[mysqld\]/a log-bin=/data/logs/bin' /etc/my.cnf
   grep "innodb_file_per_table" /etc/my.cnf || sed -i '/\[mysqld\]/a innodb_file_per_table = on' /etc/my.cnf
   grep "skip_name_resolve" /etc/my.cnf || sed -i '/\[mysqld\]/a skip_name_resolve = on' /etc/my.cnf
   grep "server-id" /etc/my.cnf || sed -i "/\[mysqld\]/a server-id=$ID" /etc/my.cnf
   service mariadb restart

2. 修改从节点57的数据库为read-only

   [root@slave data]#vi /etc/my.cnf
   [mysqld]
   read-only              

3. 记录主节点的复制位置并创建复制账号

   MariaDB [(none)]> show master logs;
   +------------+-----------+
   | Log_name   | File_size |
   +------------+-----------+
   | bin.000001 |       245 |
   +------------+-----------+
   1 row in set (0.00 sec)
   [root@master data]#mysql -e "grant replication slave on *.* to repluser@'192.168.205.%' identified by 'centos'" 

4. 修改slave的change master to,并启动i/o线程

   MariaDB [(none)]> CHANGE MASTER TO
       ->   MASTER_HOST='192.168.205.47',
       ->   MASTER_USER='repluser',
       ->   MASTER_PASSWORD='centos',
       ->   MASTER_PORT=3306,
       ->   MASTER_LOG_FILE='bin.000001',
       ->   MASTER_LOG_POS=245;
   Query OK, 0 rows affected (0.00 sec)
   
   MariaDB [(none)]> start slave;
   Query OK, 0 rows affected (0.00 sec)
   
   MariaDB [(none)]> show slave status\G
   *************************** 1. row ***************************
                  Slave_IO_State: Waiting for master to send event
                     Master_Host: 192.168.205.47
                     Master_User: repluser
                     Master_Port: 3306
                   Connect_Retry: 60
                 Master_Log_File: bin.000001
             Read_Master_Log_Pos: 401
                  Relay_Log_File: mariadb-relay-bin.000002
                   Relay_Log_Pos: 679
           Relay_Master_Log_File: bin.000001
                Slave_IO_Running: Yes
               Slave_SQL_Running: Yes

5. 导入库测试，并在从节点上查看数据库成功

   [root@master ~]#mysql < hellodb_innodb.sql 
   MariaDB [(none)]> show databases;
   +--------------------+
   | Database           |
   +--------------------+
   | information_schema |
   | hellodb            |
   | mysql              |
   | performance_schema |
   | test               |
   +--------------------+
   5 rows in set (0.00 sec)

   安装ProxySQL

6. 创建yum源，通过yum安装proxySQL

   cat <<EOF | tee /etc/yum.repos.d/proxysql.repo
   [proxysql_repo]
   name= ProxySQL YUM repository
   #baseurl=https://repo.proxysql.com/ProxySQL/proxysql-2.0.x/centos/\$releasever
   baseurl=https://repo.proxysql.com/ProxySQL/proxysql-1.4.x/centos/\$releasever
   gpgcheck=1
   gpgkey=https://repo.proxysql.com/ProxySQL/repo_pub_key
   EOF
   [root@Proxy ~]#yum install proxysql    

7. 安装一下mariadb client用来连接ProxySQL使用

   [root@Proxy ~]#yum install mariadb

8. 查看一下装了那些文件呢？好像不多呀

   [root@Proxy ~]#rpm -ql proxysql
   /etc/init.d/proxysql
   /etc/proxysql.cnf
   /usr/bin/proxysql
   /usr/share/proxysql/tools/proxysql_galera_checker.sh
   /usr/share/proxysql/tools/proxysql_galera_writer.pl

9. 启用一下服务，他会监听6032用来管理的，6033是用来用户连接的端口

   [root@Proxy ~]#service proxysql start
   Starting ProxySQL: 2019-08-12 17:00:02 [INFO] Using config file /etc/proxysql.cnf
   DONE!
   [root@Proxy ~]#ss -ntl
   State       Recv-Q Send-Q                    Local Address:Port                                   Peer Address:Port              
   LISTEN      0      128                                   *:6032                                              *:*                  
   LISTEN      0      128                                   *:6033                                              *:*                  
   LISTEN      0      128                                   *:6033                                              *:*                  
   LISTEN      0      128                                   *:6033                                              *:*                  
   LISTEN      0      128                                   *:6033                                              *:*                  
   [root@Proxy ~]#

10. 改一下我们熟悉的连接端口吧

    [root@Proxy ~]#vi /etc/proxysql.cnf
      interfaces="0.0.0.0:3306"  

11. 发现没有改过来？我们还用SQL命令来改吧

    [root@Proxy ~]#service proxysql restart
    Shutting down ProxySQL: DONE!
    Starting ProxySQL: 2019-08-12 17:03:54 [INFO] Using config file /etc/proxysql.cnf
    DONE!
    [root@Proxy ~]#ss -ntl                                   
    State       Recv-Q Send-Q                    Local Address:Port                                   Peer Address:Port              
    LISTEN      0      128                                   *:6032                                              *:*                  
    LISTEN      0      128                                   *:6033                                              *:*                  
    LISTEN      0      128                                   *:6033                                              *:*                  
    LISTEN      0      128                                   *:6033                                              *:*                  
    LISTEN      0      128                                   *:6033                                              *:*          

12. 我们使用默认的帐号来连接proxysqL,可以看到它里面一些系统库文件

    [root@Proxy ~]#mysql -uadmin -padmin -P6032 -h227.0.0.1 
    MySQL [(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)

13. show tables; 默认的是show main库的表与show tables from main;一样

    MySQL [(none)]> show tables;
    +--------------------------------------------+
    | 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)

14. 查看一

    MySQL [(none)]> select * from sqlite_master where name='mysql_servers'\G
    *************************** 1. row ***************************
        type: table
        name: mysql_servers
    tbl_name: mysql_servers
    rootpage: 2
         sql: CREATE TABLE mysql_servers (hostgroup_id INT CHECK (hostgroup_id>=0) NOT NULL DEFAULT 0 , hostname VARCHAR NOT NULL , port INT NOT NULL DEFAULT 3306 , status VARCHAR CHECK (UPPER(status) IN ('ONLINE','SHUNNED','OFFLINE_SOFT', 'OFFLINE_HARD')) NOT NULL DEFAULT 'ONLINE' , weight INT CHECK (weight >= 0) NOT NULL DEFAULT 1 , compression INT CHECK (compression >=0 AND compression <= 102400) NOT NULL DEFAULT 0 , max_connections INT CHECK (max_connections >=0) NOT NULL DEFAULT 1000 , max_replication_lag INT CHECK (max_replication_lag >= 0 AND max_replication_lag <= 126144000) NOT NULL DEFAULT 0 , use_ssl INT CHECK (use_ssl IN(0,1)) NOT NULL DEFAULT 0 , max_latency_ms INT UNSIGNED CHECK (max_latency_ms>=0) NOT NULL DEFAULT 0 , comment VARCHAR NOT NULL DEFAULT '' , PRIMARY KEY (hostgroup_id, hostname, port) )
    1 row in set (0.00 sec)

15. 修改主一下节点的记录，不管主还是从有几个节点主机添加几个，全部插入到数据库中监控

    MySQL [(none)]> insert into mysql_servers(hostgroup_id,hostname,port) values(10,'192.168.205.47',3306);
    Query OK, 1 row affected (0.00 sec)
    MySQL [(none)]> insert into mysql_servers(hostgroup_id,hostname,port) values(10,'192.168.205.57',3306);  
    Query OK, 1 row affected (0.00 sec

16. 可以看一两个节点已经插入到数据库中

    MySQL [(none)]> select * from mysql_servers;
    +--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
    | hostgroup_id | hostname       | port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
    +--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
    | 10           | 192.168.205.47 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
    | 10           | 192.168.205.57 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
    +--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
    2 rows in set (0.00 sec)

17. 加载配置，使其生效

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

18. 保存到磁盘里

    MySQL [(none)]> save mysql servers to disk;
    Query OK, 0 rows affected (0.01 sec)

19. 由于proxysql是查看主和从的数据的read_only来判读谁是主谁是从的，所以建立一账号用来连接到主和从服务器上，我们要在主节点上建立这个帐号，它会复制到从节点上

    MariaDB [(none)]> show variables like 'read_only';
    +---------------+-------+
    | Variable_name | Value |
    +---------------+-------+
    | read_only     | OFF   |
    +---------------+-------+
    1 row in set (0.00 sec)
    MariaDB [(none)]> show variables like 'read_only';
    +---------------+-------+
    | Variable_name | Value |
    +---------------+-------+
    | read_only     | ON    |
    +---------------+-------+
    1 row in set (0.00 sec)
    MariaDB [(none)]> grant replication client on *.* to monitor@'192.168.205.%' identified by 'centos';
    Query OK, 0 rows affected (0.00 sec

20. 授权proxy用这个创建的账号连接数据库，设置监控账号和口令

    MySQL [(none)]> set mysql-monitor_username='monitor';
    Query OK, 1 row affected (0.00 sec)
    MySQL [(none)]> set mysql-monitor_password='centos'; 
    Query OK, 1 row affected (0.00 sec)

21. 存盘并生效

    MySQL [(none)]> load mysql variables to runtime;                
    Query OK, 0 rows affected (0.00 sec)
    
    MySQL [(none)]> save mysql variables to disk;                   
    Query OK, 97 rows affected (0.00 sec)

22. 查看一下相关的日志，以前出错的原因是因为默认没使用monitor密码是monitor进行连接(在proxysql.cnf中可以看到)，所以会出错，当你添加完帐号就成功了,

    [root@Proxy ~]#vi /etc/proxysql.cnf
      monitor_username="monitor"
      monitor_password="monitor"
    
    MySQL [(none)]> select * from mysql_server_connect_log;
    +----------------+------+------------------+-------------------------+-------------------------------------------------------------------------+
    | hostname       | port | time_start_us    | connect_success_time_us | connect_error                                                           |
    +----------------+------+------------------+-------------------------+-------------------------------------------------------------------------+
    | 192.168.205.47 | 3306 | 1565603995322153 | 0                       | Access denied for user 'monitor'@'192.168.205.37' (using password: YES) |
    | 192.168.205.47 | 3306 | 1565604055779260 | 0                       | Access denied for user 'monitor'@'192.168.205.37' (using password: YES) |
    | 192.168.205.57 | 3306 | 1565604159035893 | 3871                    | NULL                                                                    |
    | 192.168.205.47 | 3306 | 1565604159905593 | 3563                    | NULL                                                                    |
    +----------------+------+------------------+-------------------------+-------------------------------------------------------------------------+
    22 rows in set (0.00 sec)

23. 查看ping的结果

    MySQL [(none)]> select * from mysql_server_ping_log;
    +----------------+------+------------------+----------------------+-------------------------------------------------------------------------+
    | hostname       | port | time_start_us    | ping_success_time_us | ping_error                                                              |
    +----------------+------+------------------+----------------------+-------------------------------------------------------------------------+
    | 192.168.205.57 | 3306 | 1565604094739272 | 0                    | Access denied for user 'monitor'@'192.168.205.37' (using password: YES) |
    | 192.168.205.47 | 3306 | 1565604094919486 | 0                    | Access denied for user 'monitor'@'192.168.205.37' (using password: YES) |
    | 192.168.205.57 | 3306 | 1565604099107658 | 745                  | NULL                                                                    |
    | 192.168.205.47 | 3306 | 1565604099295895 | 358                  | NULL                                                                    |
    +----------------+------+------------------+----------------------+-------------------------------------------------------------------------+
    122 rows in set (0.00 sec)

24. 查看read_only的值为空，因为没有分组

    MySQL [(none)]> select * from mysql_server_read_only_log;
    Empty set (0.00 sec)

25. 查看复制结果为空

    MySQL [(none)]> select * from mysql_server_replication_lag_log;
    Empty set (0.00 sec)

26. 需要修改的是main库中的mysql_replication_hostgroups表，该表有3个字段：writer_hostgroup, reader_hostgroup，comment, 指定写组的id为10，读组的id为20

    MySQL [(none)]> insert into mysql_replication_hostgroups values(10,20,"test");
    Query OK, 1 row affected (0.00 sec)

27. 保存生效

    MySQL [(none)]> load mysql servers to runtime;                                
    Query OK, 0 rows affected (0.00 sec)
    
    MySQL [(none)]> save mysql servers to disk;                                   
    Query OK, 0 rows affected (0.02 sec)

28. proxySQL会跟据刚才连接帐号判断read_only并自动的把两个服务器加到这个表中了

    MySQL [(none)]>  select hostgroup_id,hostname,port,status,weight from mysql_servers;
    +--------------+----------------+------+--------+--------+
    | hostgroup_id | hostname       | port | status | weight |
    +--------------+----------------+------+--------+--------+
    | 20           | 192.168.205.57 | 3306 | ONLINE | 1      |
    | 10           | 192.168.205.47 | 3306 | ONLINE | 1      |
    +--------------+----------------+------+--------+--------+
    2 rows in set (0.00 sec)
    MySQL [(none)]> select * from mysql_server_read_only_log;

29. 查看read_only的值已经有记录

    +----------------+------+------------------+-----------------+-----------+-------+
    | hostname       | port | time_start_us    | success_time_us | read_only | error |
    +----------------+------+------------------+-----------------+-----------+-------+
    | 192.168.205.57 | 3306 | 1565605365323639 | 565             | 1         | NULL  |
    | 192.168.205.47 | 3306 | 1565605365353823 | 1595            | 0         | NULL  |
    | 192.168.205.57 | 3306 | 1565605366824223 | 1275            | 1         | NULL  |
    | 192.168.205.47 | 3306 | 1565605366844952 | 1607            | 0         | NULL  |
    +----------------+------+------------------+-----------------+-----------+-------+
    280 rows in set (0.02 sec)

30. 此时proxysql还是不知道那些sql语句算读，那些为写，我们要定义好，让它来区别并发送到不同的服务器上。在主节点创建一个可以访问的帐号

    MariaDB [(none)]> grant all on *.* to sqluser@'192.168.205.%' identified by 'centos'; 
    Query OK, 0 rows affected (0.00 sec)

31. 在proxysql上定义连接时使用这个帐号去写，也就是使用10组，也就是主服务器上写

    MySQL [(none)]>  insert into mysql_users(username,password,default_hostgroup) values('sqluser','centos',10);
    Query OK, 1 row affected (0.00 sec)

32. 保存生效

    MySQL [(none)]> load mysql users to runtime;
    Query OK, 0 rows affected (0.00 sec)
    
    MySQL [(none)]> save mysql users to disk;
    Query OK, 0 rows affected (0.01 sec)

33. 现在我们使用刚才的帐号连接一下数据库(注意现在连接测试的是proxysql)，他会默认只会发送到主服务器，因为没有定义从服务器。

    [root@Proxy ~]#mysql -usqluser -pcentos -P6033 -h227.0.0.1 -e 'select @@server_id'
    +-------------+
    | @@server_id |
    +-------------+
    |          47 |
    +-------------+
    [root@Proxy ~]#mysql -usqluser -pcentos -P6033 -h227.0.0.1 -e 'create database testdb'
    [root@Proxy ~]#mysql -usqluser -pcentos testdb -P6033 -h227.0.0.1 -e 'create table t(id int)'

34. 在主服务器和从服务器上查看一下刚才创建的库和表，同步过去了

    MariaDB [(none)]> show databases;
    +--------------------+
    | Database           |
    +--------------------+
    | information_schema |
    | hellodb            |
    | mysql              |
    | performance_schema |
    | test               |
    | testdb             |
    +--------------------+
    6 rows in set (0.00 sec)
    MariaDB [(none)]> select * from testdb.t;
    Empty set (0.00 sec)

35. 目前proxysql还是不知道什么是读，什么是写，所以所有的操作都会发送到10组中，也就是主服务器上，那么现在我们来建SQL语句规则

    #select.* for updata为写向10组里发，而其它的select开头的向20组里发，也就是读，那么没定义的呢？默认会往10上发，
    MySQL [(none)]> insert into mysql_query_rules
        -> (rule_id,active,match_digest,destination_hostgroup,apply)VALUES
        -> (1,1,'^SELECT.*FOR UPDATE$',10,1),(2,1,'^SELECT',20,1);  
    Query OK, 2 rows affected (0.00 sec)
    
    #查看一下你添加的规则
    MySQL [(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$ | 10                    | 1     |
    | 2       | 1      | ^SELECT              | 20                    | 1     |
    +---------+--------+----------------------+-----------------------+-------+
    2 rows in set (0.00 sec)

36. 保存生效

    MySQL [(none)]> load mysql query rules to runtime;
    Query OK, 0 rows affected (0.00 sec)
    
    MySQL [(none)]> save mysql query rules to disk;    
    Query OK, 0 rows affected (0.01 sec)

37. 接着再次测试我们上面运行的命令,select语句就会往20上的从服务器57上发了

    [root@Proxy ~]#mysql -usqluser -pcentos -P6033 -h227.0.0.1 -e 'select @@server_id'           
    +-------------+
    | @@server_id |
    +-------------+
    |          57 |
    +-------------+

38. 如果是以一个事务来执行呢，我们发现会发送到主节点上，因为begin开始的即不是select updata开头也是select开头，所以发送到了默认节点

    [root@Proxy ~]#mysql -usqluser -pcentos -P6033 -h227.0.0.1 -e 'begin;select @@server_id;commit'       
    +-------------+
    | @@server_id |
    +-------------+
    |          47 |
    +-------------+

39. 如果是从建表操作是发送到主节点上，然后主节点再复制到从节点

    [root@Proxy ~]#mysql -usqluser -pcentos testdb -P6033 -h227.0.0.1 -e 'create table t1(id int)'
    在主节点上看这个表，发现已经建成
    Database changed
    MariaDB [testdb]> show tables;
    +------------------+
    | Tables_in_testdb |
    +------------------+
    | t                |
    | t1               |
    +------------------+
    2 rows in set (0.00 sec)
    在从节点上看也复制过去了
    MariaDB [testdb]> show tables;
    +------------------+
    | Tables_in_testdb |
    +------------------+
    | t                |
    | t1               |
    +------------------+
    2 rows in set (0.00 sec)

40. 我们可以使用proxsql查看是否调度成功

    MySQL [(none)]> select hostgroup hg,sum_time,count_star,digest_text from stats_mysql_query_digest order by sum_time desc; 
    +----+----------+------------+----------------------------------+
    | hg | sum_time | count_star | digest_text                      |
    +----+----------+------------+----------------------------------+
    | 10 | 18692    | 1          | create table t(id int)           |
    | 10 | 5704     | 1          | create table t1(id int)          |
    | 10 | 2002     | 2          | select @@server_id               |
    | 20 | 1546     | 1          | select @@server_id               |
    | 10 | 819      | 1          | begin                            |
    | 10 | 717      | 1          | create database testdb           |
    | 10 | 240      | 1          | commit                           |
    | 10 | 0        | 2          | select @@version_comment limit ? |
    | 10 | 0        | 4          | select @@version_comment limit ? |
    +----+----------+------------+----------------------------------+