HAproxy Lua：如果Lua脚本验证失败，则返回请求

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

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，该脚本本质上将根据验证结果对Validation API进行套接字调用
从验证API，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
直接来自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，我了解到有许多可用的默认功能
与Lua-Haproxy集成。

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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，我知道core.register_service基本上是从
Lua脚本。但是，有问题的是，我们必须从LUA脚本发送响应，并且它不会将请求重定向到BACKEND。
当前，我正在使用core.register_action中断请求，但是无法使用此函数返回请求。这是
我的代码如下所示：

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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：

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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，任何帮助都将受到赞赏。另外，我知道从Lua脚本进行的SOCKET调用是阻塞调用，这与HAProxy的keep-alive连接的默认性质相反。如果您已经使用过，请随时提出其他实用程序来实现此功能。

好吧，我已经找到了这个问题的答案：
我创建了2个用于成功和失败请求的后端，并根据响应返回了2个不同的字符串。在" failure_backend"中，我调用了另一个服务，该服务本质上是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：

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#---------------------------------------------------------------------
# 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：

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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)