教程 - 使用协议扩展对 syslog 消息进行负载平衡
Citrix ADC 设备上可用的系统日志协议仅适用于 Citrix ADC 设备上生成的消息。它不会对来自外部节点的消息进行负载平衡。为了平衡这些消息，您需要使用协议扩展功能，并使用 Lua 5.2 编程语言编写 syslog 消息解析逻辑。
用于解析系统日志消息的代码
代码只定义了 TCP 客户端数据回调函数-client .on_data ()。对于服务器数据，它不添加回调函数，服务器到客户端采用快速本机路径。代码基于尾随字符标识消息边界。如果 TCP 数据包包含多个 syslog 消息，那么我们根据尾随字符拆分数据包，并平衡每个消息的负载。
--[[
Syslog event handler for TCP client data
ctxt - TCP client side App processing context.
data - TCP Data stream received.
--]]
function client.on_data(ctxt, payload)
local message = nil
local data_len
local data = payload.data
local trailing_character = "\n"
::split_message::
-- Get the offset of trailing character
local new_line_character_offset = data:find(trailing_character)
-- If trailing character is not found, then wait for more data.
if (not new_line_character_offset) then
goto need_more_data
end
-- Get the length of the current message
data_len = data:len()
-- Check whether we have more than one message
-- by comparing trailing character offset and
-- current data length
if (data_len > new_line_character_offset) then
-- If we have more than one message, then split
-- the data into two parts such that first part
-- will contain message upto trailing character
-- offset and second part will contain
-- remaining message.
message, data = data:split(new_line_character_offset)
else
message = data
data = nil
end
-- Send the data to the backend server.
ns.send(ctxt.output, "EOM", {data = message})
goto done
::need_more_data::
-- Wait for more data
ctxt:hold(data)
data = nil
goto done
::done::
-- If we have more data to parse,
-- then do parsing again.
if (data) then
goto split_message
end
end
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教程 - 使用协议扩展对 syslog 消息进行负载平衡
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