部署mysql的读写分离

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1、读写分离原理：

读写分离就是在主服务器上修改，数据会同步到从服务器，从服务器只能提供读取数据，不能写入，实现备份的同时也实现了数据库性能的优化，以及提升了服务器安全。

安装环境：

linux环境	centos7.3
192.168.2.201	master主数据库
192.168.2.202	slave从数据库
192.168.2.203	mysql-proxy中间件

2、mysql的读写分离是在mysql主从复制的基础上的，所以我们先要搭建mysql的主从复制环境，之前的博客已经写到，这里不再多赘述。mysql的主从复制

下面我们在192.162.2.203机器上操作：

安装依赖：

yum install -y gcc* gcc-c++* autoconf* automake* zlib* libxml* ncurses-devel* libmcrypt* libtool* flex* pkgconfig* libevent* glib* readline-devel*

MySQL-Proxy的读写分离主要是通过rw-splitting.lua脚本实现的，因此需要安装lua。

wget http://www.lua.org/ftp/lua-5.3.4.tar.gz

tar xf lua-5.3.4.tar.gz

cd lua-5.3.4

vi src/Makefile

#替换成下面的配置内容，删除原有的
CFLAGS= -O2 -Wall -fPIC -Wextra -DLUA_COMPAT_5_2 $(SYSCFLAGS) $(MYCFLAGS)

make linux

make install

3、下载myqsl-proxy中间件安装包，解压设置属组权限。

wget https://downloads.mysql.com/archives/get/file/mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz

tar xf mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz -C /usr/local

cd /usr/local/

mv mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit /usr/local/mysql-proxy

useradd mysql-proxy

chown -R mysql-proxy.mysql-proxy mysql-proxy*

cd /usr/local/mysql-proxy

#创建存放lua的脚本和日志的两个目录
mkdir lua 
mkdir logs 


#复制读写分离配置文件
cd /usr/local/mysql-proxy/lua
cp share/doc/mysql-proxy/rw-splitting.lua .
#修改rw-splitting.lua配置内容
proxy.global.config.rwsplit = {
min_idle_connections = 1, //默认为4
max_idle_connections = 1, //默认为8
is_debug = false
}


#创建admin.lua脚本，不使用自带的admin-sql.lua脚本
vim admin.lua

#添加一下内容

--[[ $%BEGINLICENSE%$
 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

4、创建mysql-proxy启动时所需要的配置文件

vi /etc/mysql-proxy.cnf   #创建配置文件

[mysql-proxy]
user=root
admin-username=wyl
admin-password=1234
proxy-address=192.168.2.203:4040
proxy-read-only-backend-addresses=192.168.2.202:3306
proxy-backend-addresses=192.168.2.201:3306
proxy-lua-script=/usr/local/mysql-proxy/lua/rw-splitting.lua
admin-lua-script=/usr/local/mysql-proxy/lua/admin.lua
log-file=/usr/local/mysql-proxy/logs/mysql-proxy.log
log-level=info
daemon=true
keepalive=true
~

这里注意上述的配置在复制的时候注意每行后面一定不要有空格，否则会报如下的错误，尤其在复制他人博客的时候每行后面都有一个注释，就是这个地方会有空格出现。

 Key file contains key 'daemon' which has value that cannot be interpreted.

启动mysql-proxy

/usr/local/mysql-proxy/bin/mysql-proxy  --defaults-file=/etc/mysql-proxy.cnf --plugins=proxy --plugins=admin

启动后查看进程和端口：

5、创建用于读写分离的数据库连接用户
登陆主数据库服务器192.168.2.201，通过命令行登录管理MySQL服务器

[root@sqldb01 opt]# mysql -uroot -p1234

mysql> GRANT ALL ON *.* TO 'wyl'@'192.168.%.%' IDENTIFIED BY '1234';

mysql>flush privileges;

由于我们配置了主从复制功能，因此从数据库服务器192.168.2.202上已经同步了此操作。

6、在mysql-proxy的机器上进入后发现已经变成代理的mysql，version:5.0.99-agent-admin。

当输入如下指令进入数据库明令行时，可以对数据库增删改查操作。

mysql -uwyl -p1234  -h 192.168.2.203 -P4040

执行多次查询和插入询操作，如果出现下面图中的state都是up状态，则表示读写分离功能实现。