mysql-proxy 简介
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。
架构示意图
___ master_mysql(10.10.10.3) | | mysql-proxy(10.10.10.2) | |___ | slave_mysql(10.10.10.4)
(一)mysql主从同步
1、mysql-master设置
(1)
server-id = 1 //master端ID号 binlog-ignore-db = //设置不同步的sql库 binlog-do-db= //设置同步的数据
(2)设置完上面以后重启mysql
(3)添加用户访问主库,并且只有备份权限
mysql > grant replication slave on *.* to 'rsync'@'10.10.%' identified by '1q2w3e4rys' with grant option; mysql > flush privileges;
(4)锁表,主库数据继续写入
mysql > flush tables with read lock;
(5)记录 master file与position的值,slave库配置同步时候要使用
(6)导出mysql主库数据
mysqldump -uuser -p databases > databases.sql
注:这里有个问题,当主库数据上G,较大时需要做如下操作
--max_allowed_packet=XXX //客户端/服务器之间通信的缓存区的最大大小; --net_buffer_length=XXX //TCP/IP和套接字通信缓冲区大小,创建长度达net_buffer_length的行;
注意：max_allowed_packet和net_buffer_length不能比目标数据库的配置数值大,否则可能出错。
首先确定目标库的参数值
mysql>show variables like 'max_allowed_packet'; mysql>show variables like 'net_buffer_length';
根据参数值书写mysqldump命令,如:
mysql > mysqldump -uuser -p? 数据库名 -e --max_allowed_packet=1048576 --net_buffer_length=16384 > databases.sql
(7)master库同步到slave服务器上
# scp databases.sql root@host:/path
2、mysql-slave设置
(1)
server-id = 2
(2)登录mysql创建sql数据库
mysql > CREATE DATABASE `?sql_db?` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
(3)导入master库数据到slave库中
mysql -uuser -p? sql_db < databases.sql
(4)登录mysql停止slave
mysql > stop slave;
(5)配置从库同步
mysql > change master to master_host=’10.10.10.2’,master_user=’rsync’,master_password=’1q2w3e4rys’,master_port=3306,master_log_file=’mysql-bin.000047’,master_log_pos=107;
(6)启动同步功能
mysql > start slave;
(7)解除主库锁表
unlock tables;
(8)查看slave同步状态
mysql > show slave status\G //多执行几遍,查看数据写入后的状态
注：查看上面的Slave_IO_Running: Yes 和Slave_SQL_Running: Yes 2个都为yes则证明主从同步正常,如果有任一个显示NO,则证明同步有问题.可以查看数据库日志文件,里面基本上会显示出错误之处,根据错误一步一步排查,基本上都可以解决的.
(二)mysql-proxy读写分离
1、安装mysql-proxy
(1)
# wget http://ftp.ntu.edu.tw/pub/MySQL/Downloads/MySQL-Proxy/mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz # tar xf mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz -C /usr/local # cd /usr/local # ln -sv mysql-proxy-0.8.5-linux-el6-x86-64bit mysql-proxy
2、设置mysql-proxy属主属组
(1)
# groupadd mysql-proxy # useradd -g mysql-proxy -s /sbin//nologin -M mysql-proxy
3、配置mysql-proxy
(1)为mysql-proxy提供SysV服务脚本,脚本如下:
#!/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(2)将上述内容保存为/etc/rc.d/init.d/mysql-proxy,给予执行权限,而后加入到服务列表。
# chmod +x /etc/rc.d/init.d/mysql-proxy # chkconfig --add mysql-proxy
(3)为服务脚本提供配置文件/etc/sysconfig/mysql-proxy,内容如下所示：
# 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="" PROXY_USER="mysql-proxy" PROXY_OPTIONS="--daemon --log-level=info --log-use-syslog --plugins=proxy --plugins=admin --proxy-backend-addresses=10.10.10.3:3306 --proxy-read-only-backend-addresses=10.10.10.4:3306 --proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua"
(4)mysql-proxy配置选项注解
--help --help-admin --help-proxy --help-all ———— 以上四个选项均用于获取帮助信息； --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； --proxy-read-only-backend-addresses=host:port ———— 后端只读mysql服务器的地址和端口； --proxy-lua-script=file_name ———— 完成mysql代理功能的Lua脚本； --daemon ———— 以守护进程模式启动mysql-proxy； --keepalive ———— 在mysql-proxy崩溃时尝试重启之； --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； --plugins=plugin,.. ———— 在mysql-proxy启动时加载的插件； --user=user_name ———— 运行mysql-proxy进程的用户； --defaults-file=/path/to/conf_file_name ———— 默认使用的配置文件路径；其配置段使用[mysql-proxy]标识； --proxy-skip-profiling ———— 禁用profile； --pid-file=/path/to/pid_file_name ———— 进程文件名；
(5)复制如下内容建立admin.lua文件,将其保存至/usr/local/mysql-proxy/share/doc/mysql-proxy/目录中.
--[[ $%BEGINLICENSE%$
Copyright (c) 2007, 2012, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; version 2 of the
License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
02110-1301 USA
$%ENDLICENSE%$ --]]
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(6)测试
#mysql -uadmin -padmin -h110.10.10.2 --port=4041 mysql > SELECT * FROM backends;
+-------------+-------------------+-------+------+------+-------------------+ | backend_ndx | address | state | type | uuid | connected_clients | +-------------+-------------------+-------+------+------+-------------------+ | 1 | 10.10.10.3:3306 | up | rw | NULL | 0 | | 2 | 10.10.10.4:3306 | up | ro | NULL | 0 | +-------------+-------------------+-------+------+------+-------------------+ 2 rows in set (0.00 sec)
