一、使用mysql-proxy代理服务器上的mysql.sock连接
线上的mysql服务器只能使用本地的mysql.sock进行连接，非常不方便，于是想找一个中间代理来操作，之前使用过haproxy这种中间proxy，很好用。但haproxy上没有试过使用mysql.sock连接，当然mysql-proxy上的socker连接我也没有试过，但mysql-proxy毕竟是专门 的mysql proxy，我想应该会支持吧。也正好没出我所料，mysql-proxy可以支持后端直接mysql.sock文件连接。
MySQL-Proxy是一个在client端和MySQL Server间的中间层代理，它可以监测、分析或改变它们的通信。它使用灵活，没有限制，常见的用途包括：负载平衡，故障、查询分析，查询过滤和修改等等。
MySQL Proxy除了可以当做一个连接池外，还能通过使用lua脚本实现复杂的连接控制和过滤，从而实现读写分离和负载平衡。对于应用来说，MySQL Proxy是完全透明的，应用则只需要连接到MySQL Proxy的监听端口即可。另外MySQL Proxy还能实现读写分离，基本原理是让主数据库处理事务性查询，让从库处理SELECT查询。数据库复制被用来把事务性查询导致的变更同步到集群中的从库。
MySQL-Proxy官网的下载地址：MySQL :: Download MySQL Proxy (Archived Versions) 安装如下：
#找到对应的版本下载MySQL-Proxy，直接执行即可启用
root@h127:/opt/mysql-proxy# wget https://cdn.mysql.com/archives/mysql-proxy/mysql-proxy-0.8.5-linux-debian6.0-x86-64bit.tar.gz
root@h127:/opt/mysql-proxy# tar zxvf mysql-proxy-0.8.5-linux-debian6.0-x86-64bit.tar.gz
root@h127:/opt/mysql-proxy# mv mysql-proxy-0.8.5-linux-debian6.0-x86-64bit/* ./ ; cd bin
root@h127:/opt/mysql-proxy/bin# mysql-proxy --proxy-address=10.10.22.22:3307 --proxy-backend-addresses=path_to_mysql.sock --plugins=proxy
#在其它的服务器上即可进行连接
root@h191:/data$ mysql -h 10.10.22.22 -P 3307 -u read_user二、mysql-proxy的配置意义及配置示例
mysql-proxy下载下来之后，在share/doc/mysql-proxy目录中存放了各种lua文件代码示例，包括读写分享的rw-splitting.lua文件。而在另一个目录lib/mysql-proxy/plugins下存放着一些插件，比如admin,proxy插件。进入到mysql-proxy目录，执行bin/mysql-proxy --help-all可查看所有的设置选项。
root@h127:/opt/mysql-proxy$ bin/mysql-proxy --help-all
Usage:mysql-proxy [OPTION...] - MySQL Proxy
Help Options:-?, --help Show help options--help-all Show all help options--help-proxy Show options for the proxy-module
proxy-module-P, --proxy-address=<host:port> listening address:port of the proxy-server (default: :4040)-r, --proxy-read-only-backend-addresses=<host:port> address:port of the remote slave-server (default: not set)-b, --proxy-backend-addresses=<host:port> address:port of the remote backend-servers (default: 127.0.0.1:3306)--proxy-skip-profiling disables profiling of queries (default: enabled)--proxy-fix-bug-25371 fix bug #25371 (mysqld > 5.1.12) for older libmysql versions-s, --proxy-lua-script=<file> filename of the lua script (default: not set)--no-proxy don't start the proxy-module (default: enabled)--proxy-pool-no-change-user don't use CHANGE_USER to reset the connection coming from the pool (default: enabled)--proxy-connect-timeout connect timeout in seconds (default: 2.0 seconds)--proxy-read-timeout read timeout in seconds (default: 8 hours)--proxy-write-timeout write timeout in seconds (default: 8 hours)
Application Options:-V, --version Show version--defaults-file=<file> configuration file--verbose-shutdown Always log the exit code when shutting down--daemon Start in daemon-mode--user=<user> Run mysql-proxy as user--basedir=<absolute path> Base directory to prepend to relative paths in the config--pid-file=<file> PID file in case we are started as daemon--plugin-dir=<path> path to the plugins--plugins=<name> plugins to load--log-level=(error|warning|info|message|debug) log all messages of level ... or higher--log-file=<file> log all messages in a file--log-use-syslog log all messages to syslog--log-backtrace-on-crash try to invoke debugger on crash--keepalive try to restart the proxy if it crashed--max-open-files maximum number of open files (ulimit -n)--event-threads number of event-handling threads (default: 1)--lua-path=<...> set the LUA_PATH--lua-cpath=<...> set the LUA_CPATH较重要的选项功能描述如下：
[mysql-proxy] - 此为配置文件的第一行，不能少，如果少了就会报错：failed: Key file does not start with a group
--admin-address=host:port — 指定mysqo-proxy管理端口，缺省是4041
--proxy-address=host:port — 指定mysql-proxy服务端监听端口，缺省是4040
--proxy-read-only-backend-addresses=<host:port> - 读写分享只读后端
--proxy-backend-addresses=host:port — 后端MySQL服务器地址和端口，可设置多个。并且允许使用mysql.sock文件路径。
--proxy-skip-profiling — 关闭查询分析功能，缺省是打开的
--proxy-fix-bug-25371 — 修正 mysql的libmysql版本大于5.1.12的一个#25371号bug
--proxy-lua-script=file — 指定Lua脚本来控制mysql-proxy的运行
--daemon — mysql-proxy以守护进程方式运行
--pid-file=file — 设置mysql-proxy的存储PID文件的路径
--plugin-dir=<path> — 指定插件的路径
--plugins=<name> — 加载的插件，一般proxy即是代理功能；还有admin管理功能
--event-threads — 事件处理线程的个数
--log-file — 指定日志文件
--log-level — 指定日志级别
mysql-proxy配置文件示例
user@n171:/etc$ sudo cat mysql-proxy.conf
[mysql-proxy]
user=tiger
daemon=true
keepalive=true
plugins=proxy,admin
log-level=info
log-file=/opt/mysql-proxy/logs/mysql-proxy.log
proxy-address=10.10.22.11:3399
proxy-backend-addresses=/data/mysql.sock
admin-address=10.10.22.11:3388
admin-username=proxy_admin
admin-password=123456
#如果上面的plugins里加了admin,下面一定要加上amin-lua-script
admin-lua-script=/data/mysql-proxy/lib/mysql-proxy/lua/admin.luaSQL处理如下：
user@n171:/etc$ sudo cat mysql-proxy.conf
[mysql-proxy]
user=tiger
daemon=true
keepalive=true
plugins=proxy,admin
log-level=info
log-file=/opt/mysql-proxy/logs/mysql-proxy.log
proxy-address=10.10.22.11:3399
proxy-backend-addresses=/data/mysql.sock
admin-address=10.10.22.11:3388
admin-username=proxy_admin
admin-password=123456
#如果上面的plugins里加了admin,下面一定要加上amin-lua-script
admin-lua-script=/data/mysql-proxy/lib/mysql-proxy/lua/admin.luaroot@n171:/lua# mysql -h 10.10.22.11 -P 3308 -u proxy_admin -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
mysql> 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)mysql> SELECT * FROM backends;
+-------------+-----------------+-------+------+------+-------------------+
| backend_ndx | address | state | type | uuid | connected_clients |
+-------------+-----------------+-------+------+------+-------------------+
| 1 | /opt/mysql.sock | up | rw | NULL | 1 |
+-------------+-----------------+-------+------+------+-------------------+
1 row in set (0.00 sec)
