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 }
into
{ "FOO" : "bar" }
The Lua module docs for content_by_lua, which seems like the appropriate method say
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.
My understanding is that the content_by_lua is a content handler like proxy_pass, only one of which can be used per location.
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?
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
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; ------- ---------
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