MySQL-Proxy是一个处于你的client端和MySQL server端之间的简单程序，它可以监测、分析或改变它们的通信。它使用灵活，没有限制，常见的用途包括：负载平衡，故障、查询分析，查询过滤和修改等等。
MySQL-Proxy就是这么一个中间层代理，简单的说，MySQL-Proxy就是一个连接池，负责将前台应用的连接请求转发给后台的数据库，并且通过使用lua脚本，可以实现复杂的连接控制和过滤，从而实现读写分离和负载平衡。对于应用来说，MySQL-Proxy是完全透明的，应用则只需要连接到MySQL-Proxy的监听端口即可。当然，这样proxy机器可能成为单点失效，但完全可以使用多个proxy机器做为冗余，在应用服务器的连接池配置中配置到多个proxy的连接参数即可。
MySQL-Proxy更强大的一项功能是实现“读写分离”，基本原理是让主数据库处理事务性查询，让从库处理SELECT查询。数据库复制被用来把事务性查询导致的变更同步到集群中的从库。
mysql-proxy 命令
--help-all ———— 用于获取全部帮助信息
--proxy-address=host:port ———— 代理服务监听的地址和端口
--admin-address=host:port ———— 管理模块监听的地址和端口
--proxy-backend-addresses=host:port ———— 后端mysql服务器的地址和端口（主服务器）
--proxy-read-only-backend-addresses=host:port ———— 后端只读mysql服务器的地址和端口（从服务器）
--proxy-lua-script=file ———— 完成mysql代理功能的Lua脚本
--daemon ———— 以守护进程模式启动mysql-proxy
--defaults-file=/path/to/conf_file_name ———— 默认使用的配置文件路径
--log-file=/path/to/log_file_name ———— 日志文件名称
--log-level=level ———— 日志级别
--log-use-syslog ———— 基于syslog记录日志
--user=user_name ———— 运行mysql-proxy进程的用户
本文以下内容是在上一篇博客（mysql主从复制）基础上完成。
http://www.cnblogs.com/Eivll0m/p/3776496.html
1.环境及系统软件版本介绍：
系统版本：CentOS 6.3_x86_64
Mysql版本：mysql-5.6.17
mysql-proxy版本：mysql-proxy-0.8.4（下载地址：http://cdn.mysql.com/Downloads/MySQL-Proxy/mysql-proxy-0.8.4-linux-glibc2.3-x86-64bit.tar.gz）
2.部署mysql-proxy，以下操作未经特殊说明，均表示在mysql-prxoy（172.16.10.60）服务器上进行。
2.1检查是否安装了lua包，mysql-proxy需要用到lua脚本，以下表示已经安装过。
# rpm -q lua
lua-5.1.4-4.1.el6.x86_64
2.2创建代理用户
# useradd -r mysql-proxy
2.3下载通用的压缩包mysql-proxy-0.8.4-linux-glibc2.3-x86-64bit.tar.gz（直接解压使用）
# wget http://cdn.mysql.com/Downloads/MySQL-Proxy/mysql-proxy-0.8.4-linux-glibc2.3-x86-64bit.tar.gz
# tar xf mysql-proxy-0.8.4-linux-glibc2.3-x86-64bit.tar.gz -C /usr/local
# cd /usr/local/
# ln -sv mysql-proxy-0.8.4-linux-glibc2.3-x86-64bit mysql-proxy
2.4设置mysql-proxy相关文件权限
chown -R root:mysql-proxy /usr/local/mysql-proxy/*
2.5更新环境变量
# vi /etc/profile.d/mysql-proxy.sh
export PATH=$PATH:/usr/local/mysql-proxy/bin
# . /etc/profile
2.6启动mysql-proxy
# mysql-proxy --daemon --log-level=debug --log-file=/var/log/mysql-proxy.log --plugins="proxy" --proxy-backend-addresses="172.16.10.72:3306" --proxy-read-only-backend-addresses="172.16.10.61:3306"
2.7检查mysql-proxy是否正常启动
通过命令netstat -antpl|grep mysql-prxoy或tail /var/log/mysql-proxy.log进行查看
2.8在master服务器(172.16.10.72)上创建测试账号
mysql> GRANT ALL ON *.* TO proxy@'172.16.10.%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.22 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.03 sec)'
2.9在slave服务器（172.16.10.61）上测试是否能通过代理端口4040 端口连接到 mysql-proxy（以下表示测试成功）
root@mysql_slave ~]# mysql -uproxy -p -h172.16.10.60 -P 4040
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 456
Server version: 5.6.17-log Source distribution
Copyright (c) 2000, 2014, 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>
2.10配置读写分离，mysql-proxy 的安装目录中有一个名为rw-splitting.lua的 脚本，通过它可以实现读写分离，路径是/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua。
# ls /usr/local/mysql-proxy/share/doc/mysql-proxy/|grep rw-splitting.lua
rw-splitting.lua
杀掉当前mysql-proxy进程，然后把lua脚本加入到启动选项里面重新启动mysql-proxy，实现读写分离
# mysql-proxy --daemon --log-level=debug --log-file=/var/log/mysql-proxy.log --plugins="proxy" --proxy-backend-addresses="172.16.10.72:3306" --proxy-read-only-backend-addresses="172.16.10.61:3306" --proxy-lua-script=" /usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua"
查看日志
# tail /var/log/mysql-proxy.log
2014-06-13 16:23:04: (message) added read/write backend: 172.16.10.72:3306
2014-06-13 16:23:04: (message) added read-only backend: 172.16.10.61:3306
2014-06-13 16:40:11: (message) Initiating shutdown, requested from signal handler
2014-06-13 16:40:11: (message) shutting down normally, exit code is: 0
2014-06-13 16:40:17: (debug) chassis-path.c.122: adjusting relative path ( /usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua) to base_dir (/usr/local/mysql-proxy-0.8.4-linux-glibc2.3-x86-64bit). New path: /usr/local/mysql-proxy-0.8.4-linux-glibc2.3-x86-64bit/ /usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua
2014-06-13 16:40:17: (critical) plugin proxy 0.8.4 started
2014-06-13 16:40:17: (debug) max open file-descriptors = 1024
2014-06-13 16:40:17: (message) proxy listening on port :4040
2014-06-13 16:40:17: (message) added read/write backend: 172.16.10.72:3306
2014-06-13 16:40:17: (message) added read-only backend: 172.16.10.61:3306
2.11为mysql-proxy 提供一个管理接口，方便以后随时查看后端mysql 服务器的状态和访问类型，实现管理功能
# vi /usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua
function set_error(errmsg)
proxy.response = {
type = proxy.MYSQLD_PACKET_ERR,
errmsg = errmsg or "error"
}
end
function read_query(packet)
if packet:byte() ~= proxy.COM_QUERY then
set_error("[admin] we only handle text-based queries (COM_QUERY)")
return proxy.PROXY_SEND_RESULT
end
local query = packet:sub(2)
local rows = { }
local fields = { }
if query:lower() == "select * from backends" then
fields = {
{ name = "backend_ndx",
type = proxy.MYSQL_TYPE_LONG },
{ name = "address",
type = proxy.MYSQL_TYPE_STRING },
{ name = "state",
type = proxy.MYSQL_TYPE_STRING },
{ name = "type",
type = proxy.MYSQL_TYPE_STRING },
{ name = "uuid",
type = proxy.MYSQL_TYPE_STRING },
{ name = "connected_clients",
type = proxy.MYSQL_TYPE_LONG },
}
for i = 1, #proxy.global.backends do
local states = {
"unknown",
"up",
"down"
}
local types = {
"unknown",
"rw",
"ro"
}
local b = proxy.global.backends[i]
rows[#rows + 1] = {
i,
b.dst.name, -- configured backend address
states[b.state + 1], -- the C-id is pushed down starting at 0
types[b.type + 1], -- the C-id is pushed down starting at 0
b.uuid, -- the MySQL Server's UUID if it is managed
b.connected_clients -- currently connected clients
}
end
elseif query:lower() == "select * from help" then
fields = {
{ name = "command",
type = proxy.MYSQL_TYPE_STRING },
{ name = "description",
type = proxy.MYSQL_TYPE_STRING },
}
rows[#rows + 1] = { "SELECT * FROM help", "shows this help" }
rows[#rows + 1] = { "SELECT * FROM backends", "lists the backends and their state" }
else
set_error("use 'SELECT * FROM help' to see the supported commands")
return proxy.PROXY_SEND_RESULT
end
proxy.response = {
type = proxy.MYSQLD_PACKET_OK,
resultset = {
fields = fields,
rows = rows
}
}
return proxy.PROXY_SEND_RESULT
end
2.12重新启动mysql-proxy
注，这次启动要添加以下启动选项 ，因为我们添加了额外的插件，把新加功能添加进来,选项如下。
--plugins=admin 在mysql-proxy启动时加载的插件；
--admin-username="admin" 运行mysql-proxy进程管理的用户；
--admin-password="admin" 密码
--admin-lua-script="/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua" 插件使用的配置文件路径；
# killall mysql-proxy
# mysql-proxy --daemon --log-level=debug --log-file=/var/log/mysql-proxy.log --plugins="proxy" --proxy-backend-addresses="172.16.10.72:3306" --proxy-read-only-backend-addresses="172.16.10.61:3306" --proxy-lua-script=" /usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua" --plugins=admin --admin-username="admin" --admin-password="admin" --admin-lua-script="/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua"
查看mysql-proxy是否启
# netstat -antpl|grep mysql
tcp 0 0 0.0.0.0:4040 0.0.0.0:* LISTEN 9511/mysql-proxy
tcp 0 0 0.0.0.0:4041 0.0.0.0:* LISTEN 9511/mysql-proxy #4041为新生成的管理端口
2.13在slave服务器（172.16.10.61）上进行测试，使用管理端口4041 登陆，密码是admin。（测试成功！）
Bye
[root@mysql_slave ~]# mysql -uadmin -p -h172.16.10.60 -P 4041
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.0.99-agent-admin
Copyright (c) 2000, 2014, 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>
2.14测试是否可以连接
root@mysql_slave ~]# mysql -uadmin -p -h172.16.10.60 -P 4041
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.0.99-agent-admin
Copyright (c) 2000, 2014, 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 backends;
+-------------+-------------------+---------+------+------+-------------------+
| backend_ndx | address | state | type | uuid | connected_clients |
+-------------+-------------------+---------+------+------+-------------------+
| 1 | 172.16.10.72:3306 | unknown | rw | NULL | 0 |
| 2 | 172.16.10.61:3306 | unknown | ro | NULL | 0 |
+-------------+-------------------+---------+------+------+-------------------+
2 rows in set (0.00 sec)
mysql>
由于此时没有进行任何操作，所以主从状态都是unknown。
2.15配置启动脚本，并修连接端口（连接mysql-proxy时，原来用的端口是4040，下面修改为3306）
# vi /etc/sysconfig/mysql-proxy
# Options for mysql-proxy
ADMIN_USER="admin"
ADMIN_PASSWORD="admin"
ADMIN_ADDRESS=""
ADMIN_LUA_SCRIPT="/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua"
PROXY_ADDRESS="0.0.0.0:3306"
PROXY_USER="mysql-proxy"
PROXY_OPTIONS="--daemon --log-level=info --log-file="/var/log/mysql-proxy.log" --plugins=proxy --plugins=admin --proxy-backend-addresses=172.16.10.72:3306 --proxy-read-only-backend-addresses=172.16.10.61:3306 --proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua"
添加sysV脚本
# vi /etc/init.d/mysql-proxy
#!/bin/bash
#
# mysql-proxy This script starts and stops the mysql-proxy daemon
#
# chkconfig: - 78 30
# processname: mysql-proxy
# description: mysql-proxy is a proxy daemon for mysql
# Source function library.
. /etc/rc.d/init.d/functions
prog="/usr/local/mysql-proxy/bin/mysql-proxy"
# Source networking configuration.
if [ -f /etc/sysconfig/network ]; then
. /etc/sysconfig/network
fi
# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 0
# Set default mysql-proxy configuration.
ADMIN_USER="admin"
ADMIN_PASSWD="admin"
ADMIN_LUA_SCRIPT="/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua"
PROXY_OPTIONS="--daemon"
PROXY_PID=/var/run/mysql-proxy.pid
PROXY_USER="mysql-proxy"
# Source mysql-proxy configuration.
if [ -f /etc/sysconfig/mysql-proxy ]; then
. /etc/sysconfig/mysql-proxy
fi
RETVAL=0
start() {
echo -n $"Starting $prog: "
daemon $prog $PROXY_OPTIONS --pid-file=$PROXY_PID --proxy-address="$PROXY_ADDRESS" --user=$PROXY_USER --admin-username="$ADMIN_USER" --admin-lua-script="$ADMIN_LUA_SCRIPT" --admin-password="$ADMIN_PASSWORD"
RETVAL=$?
echo
if [ $RETVAL -eq 0 ]; then
touch /var/lock/subsys/mysql-proxy
fi
}
stop() {
echo -n $"Stopping $prog: "
killproc -p $PROXY_PID -d 3 $prog
RETVAL=$?
echo
if [ $RETVAL -eq 0 ]; then
rm -f /var/lock/subsys/mysql-proxy
rm -f $PROXY_PID
fi
}
# See how we were called.
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
stop
start
;;
condrestart|try-restart)
if status -p $PROXY_PIDFILE $prog >&/dev/null; then
stop
start
fi
;;
status)
status -p $PROXY_PID $prog
;;
*)
echo "Usage: $0 {start|stop|restart|reload|status|condrestart|try-restart}"
RETVAL=1
;;
esac
exit $RETVAL
# chmod +x /etc/rc.d/init.d/mysql-proxy
# chkconfig --add mysql-proxy
# chkconfig mysql-proxy on
2.16重启mysql-proxy并查看端口（4040端口已消失）
# service mysql-proxy restart
# netstat -antpl|grep mysql
tcp 0 0 0.0.0.0:4041 0.0.0.0:* LISTEN 12427/mysql-proxy
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 12427/mysql-proxy
2.17测试读写分离
执行读写操作
[root@mysql_slave ~]# mysql -uproxy -p -h172.16.10.60 -e "show databases;"
Enter password:
+--------------------+
| Database |
+--------------------+
| information_schema |
| eivll0m |
| mysql |
| performance_schema |
| test |
+--------------------+
[root@mysql_slave ~]# mysql -uproxy -p -h172.16.10.60 -e "create database mydb1;"
Enter password:
mysql> select * from backends;
+-------------+-------------------+---------+------+------+-------------------+
| backend_ndx | address | state | type | uuid | connected_clients |
+-------------+-------------------+---------+------+------+-------------------+
| 1 | 172.16.10.72:3306 | up | rw | NULL | 0 |
| 2 | 172.16.10.61:3306 | unknown | ro | NULL | 0 |
+-------------+-------------------+---------+------+------+-------------------+
2 rows in set (0.00 sec)
由于master是支持读写的，所以只发现master状态变为了up是正常现象，要想观看到从的状态，可以执行多次查询。
# mysql -uproxy -p -h172.16.10.60 -e "select user,host from mysql.user"
Enter password:
+-------+--------------+
| user | host |
+-------+--------------+
| root | 127.0.0.1 |
| proxy | 172.16.10.% |
| root | ::1 |
| | localhost |
| root | localhost |
| | mysql\_slave |
| root | mysql\_slave |
+-------+--------------+
mysql> select * from backends;
+-------------+-------------------+-------+------+------+-------------------+
| backend_ndx | address | state | type | uuid | connected_clients |
+-------------+-------------------+-------+------+------+-------------------+
| 1 | 172.16.10.72:3306 | up | rw | NULL | 0 |
| 2 | 172.16.10.61:3306 | up | ro | NULL | 0 |
+-------------+-------------------+-------+------+------+-------------------+
2 rows in set (0.00 sec)
现在，主从状态全部变成了up状态。