我们正在尝试使用HAProxy + Lua构建传入请求验证平台。 我们的用例是创建一个LUA脚本，它基本上会根据响应对Validation API进行套接字调用 从Validation API我们想要将请求重定向到后端API，如果验证失败，我们想要返回 来自LUA脚本的请求。例如，对于200响应，我们希望将请求重定向到后端api，而对于404，我们希望 返回请求。从文档中，我了解到有各种默认函数可用 与Lua-Haproxy整合。
core.register_action() --> I'm using this. Take TXN as input
core.register_converters() --> Essentially used for string manipulations.
core.register_fetches() --> Takes TXN as input and returns string; Mainly used for representing dynamic backend profiles in haproxy config
core.register_init() --> Used for initialization
core.register_service() --> You have to return the response mandatorily while using this function, which doesn't satisfy our requirements
core.register_task() --> For using normal functions. No mandatory input class. TXN is required to fetch header details from request
我已经尝试了上面列表中的所有函数，我知道core.register_service基本上是从 Lua脚本。但是，问题是，我们必须从LUA脚本发送响应，它不会将请求重定向到BACKEND。 目前，我使用core.register_action来中断请求，但我无法使用此函数返回请求。这里的 我的代码是什么样的：
local http_socket = require("socket.http")
local pretty_print = require("pl.pretty")
function add_http_request_header(txn, name, value)
local headerName = name
local headerValue = value
txn.http:req_add_header(headerName, headerValue)
end
function call_validation_api()
local request, code, header = http_socket.request {
method = "GET", -- Validation API Method
url = "http://www.google.com/" -- Validation API URL
}
-- Using core.log; Print in some cases is a blocking operation http://www.arpalert.org/haproxy-lua.html#h203
core.Info( "Validation API Response Code: " .. code )
pretty_print.dump( header )
return code
end
function failure_response(txn)
local response = "Validation Failed"
core.Info(response)
txn.res:send(response)
-- txn:close()
end
core.register_action("validation_action", { "http-req", "http-res" }, function(txn)
local validation_api_code = call_validation_api()
if validation_api_code == 200 then
core.Info("Validation Successful")
add_http_request_header(txn, "test-header", "abcdefg")
pretty_print.dump( txn.http:req_get_headers() )
else
failure_response(txn) --->>> **HERE I WANT TO RETURN THE RESPONSE**
end
end)
以下是配置文件条目：
frontend http-in
bind :8000
mode http
http-request lua.validation_action
#Capturing header of the incoming request
capture request header test-header len 64
#use_backend %[lua.fetch_req_params]
default_backend app
backend app
balance roundrobin
server app1 127.0.0.1:9999 check
在实现此功能方面，我们非常感谢您提供帮助。另外，我知道来自Lua脚本的SOCKET调用是一个阻塞调用，这与HAProxy保持连接的默认性质相反。如果您已经使用过它，请随时建议任何其他实用程序来实现此功能。
答案 0 :(得分：8)
好的，我已经找到了这个问题的答案： 我为请求的成功和失败创建了2个后端，并根据响应返回2个不同的字符串。在“failure_backend”中，我调用了一个不同的服务，它本质上是一个core.register_service，可以返回响应。我正在粘贴配置文件和lua脚本的代码
HAProxy conf文件：
#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global
# to have these messages end up in /var/log/haproxy.log you will
# need to:
#
# 1) configure syslog to accept network log events. This is done
# by adding the '-r' option to the SYSLOGD_OPTIONS in
# /etc/sysconfig/syslog
#
# 2) configure local2 events to go to the /var/log/haproxy.log
# file. A line like the following can be added to
# /etc/sysconfig/syslog
#
# local2.* /var/log/haproxy.log
#
log 127.0.0.1 local2
maxconn 4000
user haproxy
group haproxy
daemon
#lua file load
lua-load /home/aman/coding/haproxy/http_header.lua
# turn on stats unix socket
stats socket /var/lib/haproxy/stats
#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
mode http
log global
option httplog
option dontlognull
retries 3
timeout http-request 90s
timeout queue 1m
timeout connect 10s
timeout client 1m
timeout server 1m
timeout http-keep-alive 10s
timeout check 10s
maxconn 3000
#---------------------------------------------------------------------
# main frontend which proxys to the backends
#---------------------------------------------------------------------
frontend http-in
bind :8000
mode http
use_backend %[lua.validation_fetch]
default_backend failure_backend
#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend success_backend
balance roundrobin
server app1 172.23.12.94:9999 check
backend failure_backend
http-request use-service lua.failure_service
# For displaying HAProxy statistics.
frontend stats
bind :8888
default_backend stats
backend stats
stats enable
stats hide-version
stats realm Haproxy Statistics
stats uri /haproxy/stats
stats auth aman:rjil@123
Lua脚本：
local http_socket = require("socket.http")
local pretty_print = require("pl.pretty")
function add_http_request_header(txn, name, value)
local headerName = name
local headerValue = value
txn.http:req_add_header(headerName, headerValue)
end
function call_validation_api()
local request, code, header = http_socket.request {
method = "GET", -- Validation API Method
url = "http://www.google.com/" -- Validation API URL
}
-- Using core.log; Print in some cases is a blocking operation http://www.arpalert.org/haproxy-lua.html#h203
core.Info( "Validation API Response Code: " .. code )
pretty_print.dump( header )
return code
end
function failure_response(txn)
local response = "Validation Failed"
core.Info(response)
return "failure_backend"
end
-- Decides back-end based on Success and Failure received from validation API
core.register_fetches("validation_fetch", function(txn)
local validation_api_code = call_validation_api()
if validation_api_code == 200 then
core.Info("Validation Successful")
add_http_request_header(txn, "test_header", "abcdefg")
pretty_print.dump( txn.http:req_get_headers() )
return "success_backend"
else
failure_response(txn)
end
end)
-- Failure service
core.register_service("failure_service", "http", function(applet)
local response = "Validation Failed"
core.Info(response)
applet:set_status(400)
applet:add_header("content-length", string.len(response))
applet:add_header("content-type", "text/plain")
applet:start_response()
applet:send(response)
end)