【原创】MySQL Proxy - Administration Interface

【15.7.5.1. Using the Administration Interface】


       mysql-proxy 的 administration 接口可以通过任何 MySQL 客户端按照标准协议进行访问。你可以通过 administration 接口获取 proxy 服务器的整体信息 - 向 proxy 建立的标准连接是处于隔离状态的，其模拟了直接连接到后端 MySQL 服务器的情形。


       在 mysql-proxy 0.8.0 或者更早的版本中，一组最基本的接口已被添加到 proxy 中。在后续版本中，这种方式已被替换，你必须要使用的 administration 脚本以连接到 administration 接口。


       为了使用 administration 接口，需要通过 --admin-username 和 --admin-password 选项指定连接 admin 服务器所需的用户名和密码。同样必须通过 admin-lua-script 脚本选项指定提供访问 administration 服务所需接口的 Lua 脚本。


       例如，你可以使用下面的脚本创建一个访问 mysql-proxy 系统内部组件基本接口，由 Diego Medina 提供：

--[[


   Copyright 2008, 2010, 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 Street, Fifth Floor, Boston, MA 02110-1301 USA


--]]


-- admin.lua


--[[


    See http://www.chriscalender.com/?p=41
    (Thanks to Chris Calender)
    See http://datacharmer.blogspot.com/2009/01/mysql-proxy-is-back.html
    (Thanks Giuseppe Maxia)


--]]


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 = { }


    -- try to match the string up to the first non-alphanum
    local f_s, f_e, command = string.find(packet, "^%s*(%w+)", 2)
    local option


    if f_e then
            -- if that match, take the next sub-string as option
            f_s, f_e, option = string.find(packet, "^%s+(%w+)", f_e + 1)
    end


    -- we got our commands, execute it
    if command == "show" and option == "querycounter" then
            ---
            -- proxy.PROXY_SEND_RESULT requires
            --
            -- proxy.response.type to be either
            -- * proxy.MYSQLD_PACKET_OK or
            -- * proxy.MYSQLD_PACKET_ERR
            --
            -- for proxy.MYSQLD_PACKET_OK you need a resultset
            -- * fields
            -- * rows
            --
            -- for proxy.MYSQLD_PACKET_ERR
            -- * errmsg
            proxy.response.type = proxy.MYSQLD_PACKET_OK
            proxy.response.resultset = {
                    fields = {
                            { type = proxy.MYSQL_TYPE_LONG, name = "query_counter", },
                    },
                    rows = {
                            { proxy.global.query_counter }
                    }
            }


            -- we have our result, send it back
            return proxy.PROXY_SEND_RESULT
    elseif command == "show" and option == "myerror" then
            proxy.response.type = proxy.MYSQLD_PACKET_ERR
            proxy.response.errmsg = "my first error"


            return proxy.PROXY_SEND_RESULT
            
    elseif string.sub(packet, 2):lower() == 'select help' then
            return show_process_help()
    
    elseif string.sub(packet, 2):lower() == 'show proxy processlist' then
            return show_process_table()


    elseif query == "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 },
        }


        for i = 1, #proxy.global.backends do
            local b = proxy.global.backends[i]


            rows[#rows + 1] = {
                i, b.dst.name, b.state, b.type 
            }
        end
    else
        set_error()
        return proxy.PROXY_SEND_RESULT
    end


    proxy.response = {
        type = proxy.MYSQLD_PACKET_OK,
        resultset = {
            fields = fields,
            rows = rows
        }
    }
    return proxy.PROXY_SEND_RESULT
end




function make_dataset (header, dataset)
    proxy.response.type = proxy.MYSQLD_PACKET_OK


    proxy.response.resultset = {
        fields = {},
        rows = {}
    }
    for i,v in pairs (header) do
        table.insert(proxy.response.resultset.fields, {type = proxy.MYSQL_TYPE_STRING, name = v})
    end
    for i,v in pairs (dataset) do
        table.insert(proxy.response.resultset.rows, v )
    end
    return proxy.PROXY_SEND_RESULT
end


function show_process_table()
    local dataset = {}
    local header = { 'Id', 'IP Address', 'Time' }
    local rows = {}
    for t_i, t_v in pairs (proxy.global.process) do
        for s_i, s_v in pairs ( t_v ) do
            table.insert(rows, { t_i, s_v.ip, os.date('%c',s_v.ts) })
        end
    end
    return make_dataset(header,rows)
end


function show_process_help()
    local dataset = {}
    local header = { 'command',  'description' }
    local rows = {
        {'SELECT HELP',                 'This command.'},
        {'SHOW PROXY PROCESSLIST',      'Show all connections and their true IP Address.'},
    }
    return make_dataset(header,rows)
end


function dump_process_table()
    proxy.global.initialize_process_table()
    print('current contents of process table')
    for t_i, t_v in pairs (proxy.global.process) do
        print ('session id: ', t_i)
        for s_i, s_v in pairs ( t_v ) do
            print ( '\t', s_i, s_v.ip, s_v.ts )
        end
    end
    print ('---END PROCESS TABLE---')
end


--[[    Help


we use a simple string-match to split commands are word-boundaries


mysql> show querycounter


is split into
command = "show"
option  = "querycounter"


spaces are ignored, the case has to be as is.


mysql> show myerror


returns a error-packet


--]]

上述脚本需要配合下面的 proxy 脚本一起使用，名字为 reporter.lua ：

--[[


   Copyright 2008, 2010, 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 Street, Fifth Floor, Boston, MA 02110-1301 USA


--]]


-- reporter.lua


--[[


    See http://www.chriscalender.com/?p=41
    (Thanks to Chris Calender)
    See http://datacharmer.blogspot.com/2009/01/mysql-proxy-is-back.html
    (Thanks Giuseppe Maxia)


--]]


proxy.global.query_counter = proxy.global.query_counter or 0


function proxy.global.initialize_process_table()
    if proxy.global.process == nil then
        proxy.global.process = {}
    end
    if proxy.global.process[proxy.connection.server.thread_id] == nil then
        proxy.global.process[proxy.connection.server.thread_id] = {}
    end
end


function read_auth_result( auth )
    local state = auth.packet:byte()
    if state == proxy.MYSQLD_PACKET_OK then
        proxy.global.initialize_process_table()
        table.insert( proxy.global.process[proxy.connection.server.thread_id],
            { ip = proxy.connection.client.src.name, ts = os.time() } )
    end
end


function disconnect_client()
    local connection_id = proxy.connection.server.thread_id
    if connection_id then
        -- client has disconnected, set this to nil
        proxy.global.process[connection_id] = nil
    end
end




---
-- read_query() can return a resultset
--
-- You can use read_query() to return a result-set.
--
-- @param packet the mysql-packet sent by the client
--
-- @return
--   * nothing to pass on the packet as is,
--   * proxy.PROXY_SEND_QUERY to send the queries from the proxy.queries queue
--   * proxy.PROXY_SEND_RESULT to send your own result-set
--
function read_query( packet )
        -- a new query came in in this connection
        -- using proxy.global.* to make it available to the admin plugin
        proxy.global.query_counter = proxy.global.query_counter + 1


end

       为了使用上述脚本，首先需要将第一个脚本保存为文件（在下面的例子中文件名为 admin.lua ），第二个命名为 reporter.lua ，然后通过命令指定 mysql-proxy 执行的 admin 脚本和后端 MySQL 服务器：

shell> mysql-proxy --admin-lua-script=admin.lua --admin-password=password \ »
     --admin-username=root --proxy-backend-addresses=127.0.0.1:3306 -proxy-lua-script=reporter.lua

 
在另外一个窗口中，通过 proxy 连接 MySQL 服务器：

shell> mysql --user=root --password=password --port=4040
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1798669
Server version: 5.0.70-log Gentoo Linux mysql-5.0.70-r1


Type 'help;' or '\h' for help. Type '\c' to clear the buffer.


mysql>

在第三个窗口中，使用指定的用户名和密码连接 mysql-proxy 的 admin 服务：

shell> mysql --user=root --password=password --port=4041 --host=localhost
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.0.99-agent-admin


Type 'help;' or '\h' for help. Type '\c' to clear the buffer.


mysql>

为了监视 proxy 的状态信息，可以请求当前活动进行的列表信息：

mysql> show proxy processlist;
+---------+---------------------+--------------------------+
| Id      | IP Address          | Time                     |
+---------+---------------------+--------------------------+
| 1798669 | 192.168.0.112:52592 | Wed Jan 20 16:58:00 2010 | 
+---------+---------------------+--------------------------+
1 row in set (0.00 sec)


mysql>