我们首先看一下自己的环境：
MHA已经搭建：
master：172.16.16.35:3306 slave：172.16.16.35:3307 slave：172.16.16.34:3307
MHA manager在172.16.16.34，配置文件如下：
[root@localhost bin]# cat /etc/masterha/app1.cnf [server default] manager_log=/var/log/mha/app1/manager.log manager_workdir=/var/log/mha/app1.log master_binlog_dir=/home/mysql/db3306/log/ master_ip_failover_script=/usr/local/bin/master_ip_failover master_ip_online_change_script=/usr/local/bin/master_ip_online_change password=123456 ping_interval=1 remote_workdir=/tmp repl_password=123456 repl_user=root report_script=/usr/local/bin/send_report shutdown_script="" ssh_user=root user=root [server1] hostname=172.16.16.35 port=3306 [server2] candidate_master=1 check_repl_delay=0 hostname=172.16.16.34 port=3306 [server3] hostname=172.16.16.35 port=3307
下面我们基于这样一套MHA环境搭建读写分离。
1：安装ProxySQL软件，这个我们部署到172.16.16.34上
[root@localhost bin]# sudo yum install http://www.percona.com/downloads/percona-release/redhat/0.1-4/percona-release-0.1-4.noarch.rpm [root@localhost bin]# yum install proxysql
最后有以下提示：
Installed: proxysql.x86_64 0:1.3.7-1.1.el6 Complete!
也就是安装完成了。然后查一下具体的文件：
[root@localhost bin]# find / -name proxysql /var/lib/proxysql /var/run/proxysql /etc/rc.d/init.d/proxysql /usr/bin/proxysql
发现确实已经将ProxySQL安装成功了
2：启动配置ProxySQL
看一下配置文件：
[root@localhost bin]# cat /etc/proxysql-admin.cnf # proxysql admin interface credentials. export PROXYSQL_USERNAME="admin" export PROXYSQL_PASSWORD="admin" export PROXYSQL_HOSTNAME="localhost" export PROXYSQL_PORT="6032" # PXC admin credentials for connecting to pxc-cluster-node. export CLUSTER_USERNAME="admin" export CLUSTER_PASSWORD="admin" export CLUSTER_HOSTNAME="localhost" export CLUSTER_PORT="3306" # proxysql monitoring user. proxysql admin script will create this user in pxc to monitor pxc-nodes. export MONITOR_USERNAME="monitor" export MONITOR_PASSWORD="monit0r" # Application user to connect to pxc-node through proxysql export CLUSTER_APP_USERNAME="proxysql_user" export CLUSTER_APP_PASSWORD="passw0rd" # ProxySQL read/write hostgroup export WRITE_HOSTGROUP_ID="10" export READ_HOSTGROUP_ID="11" # ProxySQL read/write configuration mode. export MODE="singlewrite"
启动：
[root@localhost bin]# proxysql-admin --config-file=/etc/proxysql-admin.cnf --enable This script will assist with configuring ProxySQL (currently only Percona XtraDB cluster in combination with ProxySQL is supported) ProxySQL read/write configuration mode is singlewrite ProxySQL is not running; please start the proxysql service
现在来说ProxySQL 的路由已经启动，提示我们要启动proxysql service
[root@localhost bin]# service proxy proxy proxysql proxysql-admin proxysql_galera_checker proxysql_node_monitor [root@localhost bin]# service proxysql start Starting ProxySQL: DONE! [root@localhost bin]# mysql -uadmin -padmin -h127.0.0.1 -P6032 mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or g. Your MySQL connection id is 1 Server version: 5.7.14 (ProxySQL Admin Module) Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or 'h' for help. Type 'c' to clear the current input statement. mysql>
可以看到我们已经登录成功了，这里要说明的是 proxysql的默认配置文件是在：
[root@localhost bin]# find / -name proxysql.cnf
/etc/proxysql.cnf
接下来我们开始配置ProxySQL：
[root@localhost bin]# mysql -uadmin -padmin -h127.0.0.1 -P6032 mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or g. Your MySQL connection id is 2 Server version: 5.7.14 (ProxySQL Admin Module) Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or 'h' for help. Type 'c' to clear the current input statement. mysql> show databases; +-----+---------+-------------------------------+ | seq | name | file | +-----+---------+-------------------------------+ | 0 | main | | | 2 | disk | /var/lib/proxysql/proxysql.db | | 3 | stats | | | 4 | monitor | | +-----+---------+-------------------------------+ 4 rows in set (0.00 sec) mysql> use admin Database changed mysql> show tables; +--------------------------------------+ | tables | +--------------------------------------+ | global_variables | | mysql_collations | | mysql_query_rules | | mysql_replication_hostgroups | | mysql_servers | | mysql_users | | runtime_global_variables | | runtime_mysql_query_rules | | runtime_mysql_replication_hostgroups | | runtime_mysql_servers | | runtime_mysql_users | | runtime_scheduler | | scheduler | +--------------------------------------+ 13 rows in set (0.00 sec)
下面加入主从信息：
mysql> insert into mysql_servers(hostgroup_id,hostname,port,weight,max_connections,max_replication_lag,comment) values(100,'172.16.16.35',3306,1,1000,10,'test'); 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(101,'172.16.16.34',3306,1,1000,10,'test'); 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(101,'172.16.16.35',3307,1,1000,10,'test'); 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 | +--------------+--------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+ | 100 | 172.16.16.35 | 3306 | ONLINE | 1 | 0 | 1000 | 10 | 0 | 0 | test | | 101 | 172.16.16.34 | 3306 | ONLINE | 1 | 0 | 1000 | 10 | 0 | 0 | test | | 101 | 172.16.16.35 | 3307 | ONLINE | 1 | 0 | 1000 | 10 | 0 | 0 | test | +--------------+--------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+ 3 rows in set (0.00 sec)
然后添加读写映射（主要是MHA后端切换的时候保证ProxySQL也能够自动切换）：
mysql> insert into mysql_replication_hostgroups values(100,101,'masterha') ; Query OK, 1 row affected (0.00 sec) mysql> select * from mysql_replication_hostgroups; +------------------+------------------+----------+ | writer_hostgroup | reader_hostgroup | comment | +------------------+------------------+----------+ | 100 | 101 | masterha | +------------------+------------------+----------+ 1 row in set (0.00 sec)
为ProxySQL添加监控账号：
mysql> GRANT SUPER, REPLICATION CLIENT ON *.* TO 'proxysql'@'172.16.16.%' IDENTIFIED BY 'proxysql'; Query OK, 0 rows affected, 1 warning (0.09 sec) mysql> flush privileges; Query OK, 0 rows affected (0.10 sec)
配置监控账号（在proxySQL当中进行配置）：
mysql> set mysql-monitor_username='proxysql'; Query OK, 1 row affected (0.00 sec) mysql> set mysql-monitor_password='proxysql'; Query OK, 1 row affected (0.00 sec) mysql> load mysql variables to runtime; Query OK, 0 rows affected (0.00 sec) mysql> save mysql variables to disk; Query OK, 74 rows affected (0.02 sec)
PS:有时候runtime_mysql_servers的status不为ONLINE状态的话可以通过查看monitor.mysql_server_ping_log这个表来查看具体的报错信息。
mysql> select * from monitor.mysql_server_ping_log;
然后配置程序账号，简单点统一使用root：123456最高权限来配置：
mysql> insert into mysql_users(username,password,active,default_hostgroup,transaction_persistent) values('root','123456',1,100,1); Query OK, 1 row affected (0.00 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 | +----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+ | root | 123456 | 1 | 0 | 100 | NULL | 0 | 1 | 0 | 1 | 1 | 10000 | +----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+ 1 row in set (0.00 sec)
配置完成以后开始重新加载和保存我们的配置：
mysql> load mysql servers to runtime; Query OK, 0 rows affected (0.01 sec) mysql> save mysql servers to disk; Query OK, 0 rows affected (0.08 sec) mysql> load mysql users to runtime; Query OK, 0 rows affected (0.00 sec) mysql> save mysql users to disk; Query OK, 0 rows affected (0.03 sec)
接下来开始配置路由规则：
mysql> INSERT INTO mysql_query_rules(active,match_pattern,destination_hostgroup,apply) VALUES(1,'^SELECT.*FOR UPDATE$',100,1); Query OK, 1 row affected (0.01 sec) mysql> INSERT INTO mysql_query_rules(active,match_pattern,destination_hostgroup,apply) VALUES(1,'^SELECT',101,1); Query OK, 1 row affected (0.00 sec) mysql> LOAD MYSQL QUERY RULES TO RUNTIME; Query OK, 0 rows affected (0.00 sec) mysql> SAVE MYSQL QUERY RULES TO DISK; Query OK, 0 rows affected (0.04 sec)
至此配置已经完成了
3：测试读写分离
在172.16.16.35上链接proxySQL端口6033，并且做简单的select操作：
[root@localhost ~]# mysql -uroot -p123456 -h172.16.16.34 -P6033 mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or g. Your MySQL connection id is 22 Server version: 5.7.14 (ProxySQL) Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or 'h' for help. Type 'c' to clear the current input statement. mysql> select * from maxiangqian.test; +-----+------+ | id | name | +-----+------+ | 1 | qq | | 2 | qq | | 4 | aa | | 11 | a | | 111 | a | +-----+------+ 5 rows in set (0.04 sec)
然后在进行查询看一下：
mysql> select * from stats_mysql_query_digest;
可以看到已经完成了读写分离了。
mysql> select @@server_id; +-------------+ | @@server_id | +-------------+ | 353307 | +-------------+ 1 row in set (0.01 sec)
查看一下server ID已经路由到了172.16.16.35:3307这个从库上了。
测一下for update：
mysql> select * from maxiangqian.test for update; +-----+------+ | id | name | +-----+------+ | 1 | qq | | 2 | qq | | 4 | aa | | 11 | a | | 111 | a | +-----+------+ 5 rows in set (0.00 sec)
再查看
mysql> select * from stats_mysql_query_digest;
已经自动路由到了主库。
至此ProxySQL+MySQL MHA读写分离测试完成。。。未完待续
5：关于ProxySQL的思考以及简单的命令
ProxySQL通过以上方式是可以实现读写分离，但是这种方式真的就没有问题了吗，如果是一些比如查询订单状态的这种要求实时性非常高的SQL的话，似乎被路由到了从库就会出现BUG。我们可以选择在程序端控制这些参数，ProxySQL只作为一个负载均衡来使用，给ProxySQL创建多个账号，一个读写，一个只读。然后程序去实现读写分离。
ProxySQL是分三层来设计运行的，分别为RUNTIME ，MEMORY ，DISK ：
RUNTIME 代表的是ProxySQL当前生效的配置，包括 global_variables, mysql_servers, mysql_users, mysql_query_rules。无法直接修改这里的配置，必须要从下一层load进来。
MEMORY 是平时在mysql命令行修改的 main 里头配置，可以认为是SQLite数据库在内存的镜像
DISK / CONFIG FILE 持久存储的那份配置，一般在$(DATADIR)/proxysql.db，在重启的时候会从硬盘里加载。 /etc/proxysql.cnf文件只在第一次初始化的时候用到，完了后，如果要修改监听端口，还是需要在管理命令行里修改，再 save 到硬盘
常用命令：
LOAD MYSQL SERVERS TO RUNTIME -- 让修改的配置生效，也就是从MEMORY 把参数LOAD过来，等价于LOAD MYSQL USERS FROM MEMORY，这个语句的语法比较单间，FROM代表从上层LOAD过来，TO代表从本层到某一个层。比如前面我们设置了MySQL的监控账号，但是还是要执行LOAD和SAVE保存变量并且使变量生效。