validation - HAproxy+Lua : Return requests if validation fails from Lua script

Question

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，该脚本基本上将对验证 API 进行套接字调用，并基于响应
从验证 API 中，我们希望将请求重定向到后端 API，如果验证失败，我们希望返回
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，对于 404，我们希望
返回请求。从文档中，我了解到有各种默认功能可用
与 Lua-Haproxy 集成。

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功能，我明白 core.register_service 基本上是从
Lua 脚本。然而，有问题的是，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，我正在使用 core.register_action 来中断请求，但我无法使用此函数返回请求。这是
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

非常感谢在实现此功能方面的任何帮助。另外，我知道来自 Lua 脚本的 SOCKET 调用是一个阻塞调用，这与 HAProxy 的保持事件连接的默认性质相反。如果您已经使用过它，请随时提出任何其他实用程序来实现此功能。

Answer 1

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，并根据响应返回了 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 并且可以返回响应。我正在粘贴配置文件和 lua 脚本的代码

HAProxy 配置文件:

#---------------------------------------------------------------------
# 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)