mysql-proxy实现mysql读写分离的配置
例子1
1、安装mysql-proxy
此处下载安装包http://ftp.ntu.edu.tw/pub/MySQL/Downloads/MySQL-Proxy/
如果是编译安装依赖包有 libevent2 1.x lua 5.1.x glibc2 2.6.0 pkg-config libtool 1.5
这里使用glibc的二进制包解压即可mysql-proxy-0.8.3-linux-glibc2.3-x86-64bit.tar.gz
tar -zxvf mysql-proxy-0.8.3-linux-glibc2.3-x86-64bit.tar.gz
mv mysql-proxy-0.8.3-linux-glibc2.3-x86-64bit /usr/local/mysql-proxy
2、创建好mysql主从复制
master 192.168.216.133：3306
slave 192.168.216.132：3306
3、配置mysql-proxy
创建mysql-proxy配置文件，配置文件中的所有选择都不能加引号
vim /usr/local/mysql-proxy/mysql-proxy.conf
[mysql-proxy]
daemon=true #以后台守护进程方式启动
keepalive=true #当进程故障后自动重启
log-level=debug #设置日志级别为debug，可以在调试完成后改成info
log-file=/var/log/mysql-proxy.log #设置日志文件路径
basedir=/usr/local/mysql-proxy #设置mysql-proxy的家目录
proxy-address=192.168.216.132:4040 #指定mysql-proxy的监听地址
proxy-backend-addresses=192.168.216.133:3306 #设置后台主服务器
proxy-read-only-backend-addresses=192.168.216.132:3306 #设置后台从服务器
proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua #设置读写分离脚本路径
admin-address=192.168.216.132:4041 #设置mysql-proxy管理地址，需要家长admin插件
admin-username=admin #设置登录管理地址用户
admin-password=admin #设置管理用户密码
admin-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua #设置管理后台lua脚本路径，改脚本默认没有要自动定义
配置完mysql-proxy.conf后需要确保该文件的权限是600，并确保包含个lua脚本
通过配置文件启动mysql-proxy
/usr/local/mysql-proxy/bin/mysql-proxy --plugins=proxy --plugins=admin --defaults-file=mysql-proxy.conf
--plugins=proxy #指定proxy插件，该配置写入配置文件无法启动
--plugins=admin #指定admin插件
--defaults-file=mysql-proxy.conf #指定配置文件
4、启动测试
登录管理地址查看当前状态
mysql -uadmin -padmin -h192.168.216.132 -P4041
两个后端服务器当前状态为unknown是因为没有用户通过mysql-proxy连接到后端
mysql-proxy不对用户做身份验证，而是下身份验证交予后端服务器进行验证的，因此需要在后端服务器上对mysql-proxy开放权限
下面是自定义的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
5、遇到的问题
1、如果日志中提示 (debug) [network-mysqld.c:1134]: error on a connection (fd: -1 event: 0). closing client connection.
可以修改 rw-splitting.lua中的min_idle_connections = 4和max_idle_connections = 8的只，将其调大
2、如果遇到乱码需要调整后端mysql的设置的字符集
[mysqld]
skip-character-set-client-handshake
init-connect = 'SET NAMES utf8'
character_set_server = utf8
例子2
用MySQL-Proxy实现读写分离
实现读写分离的LUA脚本是简单明了的：
-- 读写分离
--
-- 发送所有的非事务性SELECT到一个从数据库
if is_in_transaction == 0 and
packet:byte() == proxy.COM_QUERY and
packet:sub(2, 7) == "SELECT" then
local max_conns = -1
local max_conns_ndx = 0
for i = 1, #proxy.servers do
local s = proxy.servers[i]
-- 选择一个拥有空闲连接的从数据库
if s.type == proxy.BACKEND_TYPE_RO and
s.idling_connections > 0 then
if max_conns == -1 or
s.connected_clients < max_conns then
max_conns = s.connected_clients
max_conns_ndx = i
end
end
end
-- 我们找到了一个拥有空闲连接的从数据库
if max_conns_ndx > 0 then
proxy.connection.backend_ndx = max_conns_ndx
end
else
-- 发送到主数据库
end
return proxy.PROXY_SEND_QUERY
Jan提醒说这个技巧还可以用来实现其他的数据分布策略，例如分片（Sharding）
