如何使用Nginx和Lua处理POST请求的JSON主体? [英] How can I manipulate the JSON body of a POST request using Nginx and Lua?

问题描述

我正在做一个概念验证，以演示如何在堆栈中实现 3scale .在一个示例中，我想执行一些POST request 正文操作，以创建一个API外观，该外观将旧API格式映射为新的内部API格式.例如.更改类似

I am doing a proof of concept to demonstrate how we might implement 3scale in our stack. In one example I want to do some POST request body manipulation to create an API façade that maps what might be a legacy API format to a new internal one. Eg. change something like

{ "foo" : "bar" , "deprecated" : true }

进入

{ "FOO" : "bar" }

content_by_lua 的 Lua模块文档，适当的方法说

The Lua module docs for content_by_lua, which seems like the appropriate method say

请勿在同一位置使用此指令和其他内容处理程序指令.例如，该指令和 proxy_pass 指令不得用于相同的位置.

Do not use this directive and other content handler directives in the same location. For example, this directive and the proxy_pass directive should not be used in the same location.

我的理解是content_by_lua是类似于proxy_pass的内容处理程序，每个位置只能使用其中一个.

My understanding is that the content_by_lua is a content handler like proxy_pass, only one of which can be used per location.

我认为无法删除 proxy_pass ，因为这是代理工作方式的基础，因此可以使用 content_by_lua 来将请求捕获到一个单独的位置 strong>，然后转到实现 proxy_pass 的位置，或者是否有其他方法，例如 strong> rewrite_by_lua 哪个更合适?

I don't think there's any way to remove proxy_pass as that's the basis of how the proxying works, so is it possible capture the request in a separate location, use content_by_lua, then pass to the location implementing proxy_pass or is there a different method like rewrite_by_lua which is more appropriate?

如果对其他人有帮助，我添加了以下函数(我的Lua的第一位)，该函数删除了3scale要求授权的user_key参数，但如果在以下位置转发，则对我们的API无效:

If it helps anyone else, I added the following function (my first bit of Lua) which removes the user_key parameter which 3scale requires for authorization but is invalid for our API if forwarded on:

function remove_user_key()
  ngx.req.read_body()
  -- log the original body so we can compare to the new one later
  local oldbody = ngx.req.get_body_data()
  log(oldbody)
  -- grab the POST parameters as a table
  local params = ngx.req.get_post_args()

  -- build up the new JSON string
  local newbody = "{"

   for k,v in pairs(params) do
     -- add all the params we want to keep
     if k ~= "user_key" then
        log("adding"..k.." as "..v)
        newbody = newbody..'"'..k..'":"'..v..'",'
     else 
        log("not adding user_key")
     end
   end
  --remove the last trailing comma before closing this off
  newbody = string.sub(newbody, 0, #newbody-1)
  newbody = newbody.."}"

  ngx.req.set_body_data(newbody)
  log(newbody)
end

if ngx.req.get_method() == "POST" then
  remove_user_key()
end

推荐答案

我建议您使用access_by_lua
在nginx.conf

I will suggest you to use access_by_lua
in nginx.conf

location / {
                #host and port to fastcgi server
                default_type text/html;
                set $URL "http://$http_host$request_uri";
                access_by_lua_file /home/lua/cache.lua;
                proxy_pass http://$target;
                -------
                ---------

在cache.lua文件中，您可以执行以下操作:

in cache.lua file you can do something like :

if ngx.req.get_method() == "POST" then
    -- check if request method is POST 
    -- implement your logic 
    return
end

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