使用mysql-proxy-0.8.5实现MySQL读写分离

实验环境：RHEL6.6-x86-64
mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz
mysql-5.6.14-linux-glibc2.5-x86_64.tar.gz

为了减轻数据库负载，可以考虑使用读写分离来实现。目前实现读写分离的方式大约有两种：

基于程序代码实现

在程序代码中根据select、insert语句进行路由分类。读写分别由不同Server响应。

基于中间代理层实现

代理位于客户端与服务端之间，代理层接收客户端请求后，判断读写请求转发至不同Server。 mysql-proxy便是其中一种。它可以监视，分析，改变它们的会话。他有多种用途，负载均衡， 查询分析，查询过滤和修改等。




MySQL主从搭建，请参考我的另一篇文章，这里不再赘述。

安装mysql-proxy

# useradd -r mysql-proxy
# tar xf mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz -C /usr/local/
# cd /usr/local/
# ln -s mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit mysql-proxy

vim /etc/profile.d/mysql-proxy.sh
export PATH=$PATH:/usr/local/mysql-proxy/bin

为/etc/init.d/mysql-proxy提供参数

# vim /etc/sysconfig/mysql-proxy
ADMIN_USER="admin"
ADMIN_PASSWORD="admin"
ADMIN_ADDRESS=""
PROXY_ADDRESS="0.0.0.0:3306"
PROXY_USER="mysql-proxy"
PROXY_PID=/var/run/mysql-proxy.pid
PROXY_OPTIONS="--daemon"
ADMIN_LUA_SCRIPT="/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua"
RW_SPLITTING_LUA_SCRIPT=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua
PROXY_OPTIONS="--daemon --log-level=info --log-file="/var/log/mysql-proxy.log" --plugins=proxy --plugins=admin --proxy-backend-addresses=192.168.1.5:3306 --proxy-read-only-backend-addresses=192.168.1.6:3306 --proxy-lua-script=$RW_SPLITTING_LUA_SCRIPT --pid-file=$PROXY_PID --proxy-address=$PROXY_ADDRESS --user=$PROXY_USER --admin-username=$ADMIN_USER --admin-lua-script=$ADMIN_LUA_SCRIPT --admin-password=$ADMIN_PASSWORD"

为mysql-proxy提供sysv风格脚本

vim /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"
# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 0

# Source mysql-proxy configuration.
if [ -f /etc/sysconfig/network ]; then
. /etc/sysconfig/network
fi
# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 0
# 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 $PROXY_OPTIONS
RETVAL=$?
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

为管理提供lua脚本

vim /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

# chmod +x /etc/init.d/mysql-proxy
# service mysql-proxy start

连接至管理
# mysql -uadmin -h192.168.1.7 --port=4041 -p
查看状态可看到state是unknown

mysql> SELECT * FROM backends;
+-------------+------------------+---------+------+------+-------------------+
| backend_ndx | address          | state   | type | uuid | connected_clients |
+-------------+------------------+---------+------+------+-------------------+
|           1 | 192.168.1.5:3306 | unknown | rw   | NULL |                 0 |
|           2 | 192.168.1.6:3306 | unknown | ro   | NULL |                 0 |
+-------------+------------------+---------+------+------+-------------------+

连接至mysql-proxy
# mysql -uroot -p -h192.168.1.7
插入、查询各执行几次

再连接至管理查看状态,可看到状态是up。

mysql> SELECT * FROM backends;
+-------------+------------------+-------+------+------+-------------------+
| backend_ndx | address          | state | type | uuid | connected_clients |
+-------------+------------------+-------+------+------+-------------------+
|           1 | 192.168.1.5:3306 | up    | rw   | NULL |                 0 |
|           2 | 192.168.1.6:3306 | up    | ro   | NULL |                 0 |
+-------------+------------------+-------+------+------+-------------------+

读写分离实现完成。

本文出自 “在路上” 博客，请务必保留此出处http://mingxiao.blog.51cto.com/8124243/1651726