CentOS 7.2下MySQL读写分离配置

MySQL读写分离配置

环境：CentOS7.2 MySQL5.7

场景描述：
数据库Master主服务器：192.168.206.100
数据库Slave从服务器：192.168.206.200
 MySQL-Proxy调度服务器：192.168.206.210

以下操作，均是在192.168.206.210即MySQL-Proxy调度服务器 上进行的。

1.检查系统所需软件包

安装之前需要配置EPEL YUM源
wget https://mirrors.ustc.edu.cn/epel//7/x86_64/Packages/e/epel-release-7-11.noarch.rpm
rpm -ivh epel-release-7-11.noarch.rpm
yum clean all
yum update

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

2.编译安装lua

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

lua可通过以下方式获得
 从http://www.lua.org/download.html下载源码包

从rpm.pbone.net搜索相关的rpm包
download.Fedora.RedHat.com/pub/fedora/epel/5/i386/lua-5.1.4-4.el5.i386.rpm
 download.fedora.redhat.com/pub/fedora/epel/5/x86_64/lua-5.1.4-4.el5.x86_64.rpm

这里我们建议采用源码包进行安装
cd /opt/install
wget http://www.lua.org/ftp/lua-5.1.4.tar.gz
tar zvfx lua-5.1.4.tar.gz
cd lua-5.1.4
make linux
make install
mkdir /usr/lib/pkgconfig/
cp /opt/install/lua-5.1.4/etc/lua.pc /usr/lib/pkgconfig/
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/lib/pkgconfig

注意的问题

编译的时候，遇到的问题是，缺少依赖包** readline**, 然后readline又依赖ncurses,所以要先安装着两个软件
yum install -y readline-devel ncurses-devel

3.安装配置MySQL-Proxy

下载mysql-proxy

下载：http://dev.mysql.com/downloads/mysql-proxy/
wget https://downloads.mysql.com/archives/get/file/mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz
tar zxvf mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz
mv zxvf mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit /usr/local/mysql-proxy

** 配置mysql-proxy，创建主配置文件**
cd /usr/local/mysql-proxy
mkdir lua #创建脚本存放目录
mkdir logs #创建日志目录
cp share/doc/mysql-proxy/rw-splitting.lua  ./lua #复制读写分离配置文件
vi /etc/mysql-proxy.cnf  #创建配置文件
[mysql-proxy]
user=root #运行mysql-proxy用户
admin-username=proxyuser #主从mysql共有的用户
admin-password=123456 #用户的密码
proxy-address=192.168.206.210:4040 #mysql-proxy运行ip和端口，不加端口，默认4040
proxy-read-only-backend-addresses=192.168.206.200 #指定后端从slave读取数据
proxy-backend-addresses=192.168.206.100 #指定后端主master写入数据
proxy-lua-script=/usr/local/mysql-proxy/lua/rw-splitting.lua #指定读写分离配置文件位置
admin-lua-script=/usr/local/mysql-proxy/lua/admin.lua #指定管理脚本
log-file=/var/log/mysql-proxy.log #日志位置
log-level=info #定义log日志级别
daemon=true#以守护进程方式运行
keepalive=true #mysql-proxy崩溃时，尝试重启

这里就有一个坑了

配置文件里面的注释要全部删掉，不然可能会引起一些字符不能识别的错误。
 这还不是最坑的，最坑的是：即使删掉注释，去除多余的空白字符，仍然可能会报如下错误：
2018-09-21 06:39:40: (critical) Key file contains key “daemon” which has a value that cannot be interpreted.

或者：
2018-09-21 06:52:22: (critical) Key file contains key “keepalive” which has a value that cannot be interpreted.

出现以上问题的原因是daemon=true，keepalive=true现在不这样写了，要改为：
daemon=1
keepalive=1

给配置文件执行权限
chmod 660 /etc/mysql-porxy.cnf

配置admin.lua 文件

在/etc/mysql-proxy.cnf 配置文件中，还差/usr/local/mysql-proxy/lua/admin.lua 的管理文件，实际现在还没有创建的。所以，现在需要编辑创建admin.lua文件。mysql-proxy-0.8.5的这个版本，我找到了下面的admin.lua脚本，对这个版本才是有效的：
vim  /usr/local/mysql-proxy/lua/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

** 修改读写分离配置文件**
vim /usr/local/mysql-proxy/lua/rw-splitting.luaif not proxy.global.config.rwsplit
 proxy.global.config.rwsplit = {
  min_idle_connections = 1, #默认超过4个连接数时，才开始读写分离，改为1
  max_idle_connections = 1, #默认8，改为1
  is_debug = false
 }
end

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

netstat -tupln | grep 4000 #已经启动killall -9 mysql-proxy #关闭mysql-proxy