mysql读写分离[高可用]

顾名思义, 在mysql负载均衡中有多种方式, 本人愚钝,只了解驱动中间件和mysql_proxy两种方式, 对于驱动,利用的是ReplicationDriver,具体请看远哥的这篇文章: MySQL读写分离又一好办法 使用 com.mysql.jdbc.ReplicationDriver

本次我要实现利用的方式是: mysql_proxy

下面进入主题

mysql_proxy:192.168.99.55

master:192.168.99.61

slave:192.168.99.62

1.安装mysql_proxy

tar -zxvf mysql-proxy-0.8.4-linux-rhel5-x86-64bit.tar.gz -C /usr/local

cd /usr/local

mv mysql-proxy-0.8.4-linux-rhel5-x86-64bit mysql-proxy

下面是需要的依赖

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

2.添加代理用户

useradd -r mysql-proxy

3.sysv服务脚本mysql_proxy

这个脚本放置的位置是：/etc/init.d

记得授权，chmod +x /etc/init.d/mysql_proxy

这个脚本是用来做快捷启动的。

#!/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

4.为服务脚本提供配置文件mysql_proxy

这个脚本放在的位置是:/etc/sysconfig(我是根据上面服务脚本的位置放的, 喜欢放在别处的地方可以自行修改)。

# 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=192.168.99.61:3306 
--proxy-read-only-backend-addresses=192.168.99.62:3306 --proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua"

5.创建admin.lua

这个脚本放置的位置是:/usr/local/mysql-proxy/share/doc/mysql-proxy

--[[ $%BEGINLICENSE%$
 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.修改rw-splitting.lua

修改的是min_idle_connections和max_idle_connections的值,都等于1

local commands    = require("proxy.commands")
local tokenizer   = require("proxy.tokenizer")
local lb          = require("proxy.balance")
local auto_config = require("proxy.auto-config")

--- config
--
-- connection pool
if not proxy.global.config.rwsplit then
	proxy.global.config.rwsplit = {
		min_idle_connections = 1,
		max_idle_connections = 1,

		is_debug = false
	}
end

7.测试mysql_proxy

7.1启动mysql_proxy

service mysql_proxy start

7.2端口进程状态

进程

ps aux | grep mysql-proxy


root     14230  0.0  0.0 103244   836 pts/0    S+   11:25   0:00 grep mysql-proxy
496      28239  0.0  0.0  45772  2104 ?        S    Dec04   0:03 /usr/local/mysql-proxy/libexec/mysql-proxy --daemon --log-level=info --log-use-syslog --plugins=proxy --plugins=admin --proxy-backend-addresses=192.168.75.61:3306 --proxy-read-only-backend-addresses=192.168.75.62:3306 --proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua --pid-file=/var/run/mysql-proxy.pid --proxy-address= --user=mysql-proxy --admin-username=admin --admin-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua --admin-password=admin

端口

netstat -tlnp | grep mysql-proxy


tcp        0      0 0.0.0.0:4041                0.0.0.0:*                   LISTEN      28239/mysql-proxy   
tcp        0      0 0.0.0.0:3306                0.0.0.0:*                   LISTEN      28239/mysql-proxy   

看到上面, 端口有4041与3306, 这两个端口都是关键所在,下面将进行解题。

7.3登录mysql_proxy

随便找一台有mysql客户端的机器登录到mysql_proxy192.168.99.55(也可以在99.55上面安装mysql客户端, 我是在别的机器连得), 这个登录使用的账号密码还记得把?它就是脚本中指定的账号密码,admin:admin

mysql -u admin -p -h 192.168.99.55 --port=4041

必须指定端口, 不然跑的是3306

7.4查询状态

7.4.1 select * from help

+------------------------+------------------------------------+
| command                | description                        |
+------------------------+------------------------------------+
| SELECT * FROM help     | shows this help                    |
| SELECT * FROM backends | lists the backends and their state |
+------------------------+------------------------------------+
2 rows in set (0.00 sec)

7.4.2 SELECT * FROM backends

+-------------+--------------------+-------+------+------+-------------------+
| backend_ndx | address            | state | type | uuid | connected_clients |
+-------------+--------------------+-------+------+------+-------------------+
|           1 | 192.168.99.61:3306 | down    | rw   | NULL |                 0 |
|           2 | 192.168.99.62:3306 | down    | ro   | NULL |                 0 |
+-------------+--------------------+-------+------+------+-------------------+
2 rows in set (0.00 sec)

看到上面的信息, master99.61的type是rw(支持读写),slave99.62的type是ro(只读)

7.5抓包分析

在master上:

tcpdump -i eth0 -nn -XX ip dst 192.168.99.61 and tcp dst port 3306

在slave上:

tcpdump -i eth0 -nn -XX ip dst 192.168.99.62 and tcp dst port 3306

7.5.1主从分析

为了更明显操作结果, 停止主从

登录mysql_proxy

mysql -u admin -p -h 192.168.75.55 --port=3306

这次登录的是3306, 上面登录的是4041,请大家不要混淆。

至于3306与4041有什么不一样， 下面我解析一下， 4041就是查询读写分离的状态的， 3306无疑就是提供给外部的接口。

现在往test表插入一条数据

insert into test.testtest values(80,'80');

下面查询, 是查询不到的, 因为主从已经断开, 查的是往62跑, 写是写进61了, 只要把主从配置回来一切正常。

上面的抓包就是没操作一下都会有记录, 这次很明显看出来读写分析所跑的机器。

进行写时, master抓到的包是:

14:25:28.835455 IP 192.168.99.55.45648 > 192.168.99.61.3306: Flags [P.], seq 2082548409:2082548453, ack 3795613073, win 173, options [nop,nop,TS val 2915927263 ecr 2948974813], length 44
        0x0000:  0050 5689 cba6 0050 5689 9616 0800 4508  .PV....PV.....E.
        0x0010:  0060 994f 4000 4006 897b c0a8 4b37 c0a8  .`.O@.@..{..K7..
        0x0020:  4b3d b250 0cea 7c21 2ab9 e23c 7591 8018  K=.P..|!*..<u...
        0x0030:  00ad eed3 0000 0101 080a adcd 84df afc5  ................
        0x0040:  c8dd 2800 0000 0369 6e73 6572 7420 696e  ..(....insert.in
        0x0050:  746f 2074 6573 742e 7465 7374 7465 7374  to.test.testtest
        0x0060:  2076 616c 7565 7328 322c 2732 2729       .values(2,'2')
14:25:28.836543 IP 192.168.99.55.45648 > 192.168.99.61.3306: Flags [.], ack 12, win 173, options [nop,nop,TS val 2915927264 ecr 2949040785], length 0
        0x0000:  0050 5689 cba6 0050 5689 9616 0800 4508  .PV....PV.....E.
        0x0010:  0034 9950 4000 4006 89a6 c0a8 4b37 c0a8  .4.P@.@.....K7..
        0x0020:  4b3d b250 0cea 7c21 2ae5 e23c 759c 8010  K=.P..|!*..<u...
        0x0030:  00ad f329 0000 0101 080a adcd 84e0 afc6  ...)............

slave此时的状态是:

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes

进行读时, slave的状态是:

15:00:36.252068 IP 192.168.99.55.40191 > 192.168.99.62.3306: Flags [P.], seq 853416170:853416202, ack 2118301929, win 184, options [nop,nop,TS val 2915944710 ecr 2911691799], length 32
        0x0000:  0050 5689 a328 0050 5689 9616 0800 4508  .PV..(.PV.....E.
        0x0010:  0054 7caa 4000 4006 a62b c0a8 4b37 c0a8  .T|.@.@..+..K7..
        0x0020:  4b3e 9cff 0cea 32de 18ea 7e42 b8e9 8018  K>....2...~B....
        0x0030:  00b8 0093 0000 0101 080a adcd c906 ad8c  ................
        0x0040:  e417 1c00 0000 0373 656c 6563 7420 2a20  .......select.*.
        0x0050:  6672 6f6d 2074 6573 742e 7465 7374 7465  from.test.testte
        0x0060:  7374                                     st
15:00:36.253339 IP 192.168.99.55.40191 > 192.168.99.62.3306: Flags [.], ack 144, win 223, options [nop,nop,TS val 2915944712 ecr 2912255989], length 0
        0x0000:  0050 5689 a328 0050 5689 9616 0800 4508  .PV..(.PV.....E.
        0x0010:  0034 7cab 4000 4006 a64a c0a8 4b37 c0a8  .4|.@.@..J..K7..
        0x0020:  4b3e 9cff 0cea 32de 190a 7e42 b978 8010  K>....2...~B.x..
        0x0030:  00df 8c29 0000 0101 080a adcd c908 ad95  ...)............
        0x0040:  7ff5                                     ..

最终拓扑