Kong plugin do not run access block - api

Question

I'm developing a plugin to Kong API Gateway. I created a service pointing it to another service in the local network and basically every request to my service is redirected to the other one, so far so good.
What the plugin has to do is grab the field Authorization Bearer in the header, and pass to the upstream service as part of the URI. E.g.
Request is received on:
localhost/service
In its header, it have a Authorization Bearer that contains a JWT
The plugin has to receive it, take the JWT and parse it to URI to the upstream service:
productionServer/service/9a8udoadzlkndid813gru1gr <-JWT took from header
My attempt till now:
local singletons = require "kong.singletons"
local BasePlugin = require "kong.plugins.base_plugin"
local responses = require "kong.tools.responses"
local constants = require "kong.constants"
local multipart = require "multipart"
local cjson = require "cjson"
local url = require "socket.url"
local access = require "kong.plugins.ctk.access"
local CtkHandler = BasePlugin:extend()
CtkHandler.PRIORITY = 3505
CtkHandler.VERSION = "0.1.0"
file = io.open("/usr/local/kong/logs/ctk.lua", "a+")
io.input(file)
file:write("--- JUST EXTENDED THE BASE PLUGIN ---")
function CtkHandler:new()
CtkHandler.super.new(self, "ctk")
file = io.open("/usr/local/kong/logs/ctk.lua", "a+")
io.input(file)
file:write("--- INSTACIATED ITSELF ---")
end
function CtkHandler:access(conf)
CtkHandler.super.access(self)
file = io.open("/usr/local/kong/logs/ctk.lua", "a+")
io.input(file)
file:write("--- STARTED THE ACCESS PART ---")
do_authentication()
access.execute(conf)
end
file:close()
return CtkHandler
The idea, is that after every request, the access block at the end be executed, then, he will redirect to my access file
local singletons = require "kong.singletons"
local BasePlugin = require "kong.plugins.base_plugin"
local responses = require "kong.tools.responses"
local constants = require "kong.constants"
local multipart = require "multipart"
local cjson = require "cjson"
local url = require "socket.url"
local basic_serializer = require "kong.plugins.log-serializers.basic"
local string_format = string.format
local ngx_set_header = ngx.req.set_header
local get_method = ngx.req.get_method
local req_set_uri_args = ngx.req.set_uri_args
local req_get_uri_args = ngx.req.get_uri_args
local req_set_header = ngx.req.set_header
local req_get_headers = ngx.req.get_headers
local req_clear_header = ngx.req.clear_header
local req_set_method = ngx.req.set_method
local ngx_decode_args = ngx.decode_args
local ngx_re_gmatch = ngx.re.gmatch
local string_format = string.format
local cjson_encode = cjson.encode
local ipairs = ipairs
local request = ngx.request
local function retrieve_token(request, conf)
file = io.open("/usr/local/kong/logs/ctk.lua", "a+")
io.input(file)
file:write("--- RUNNING RETRIEVE TOKEN ---")
local uri_parameters = request.get_uri_args()
for _, v in ipairs(conf.uri_param_names) do
if uri_parameters[v] then
return uri_parameters[v]
end
end
local ngx_var = ngx.var
for _, v in ipairs(conf.cookie_names) do
local jwt_cookie = ngx_var["cookie_" .. v]
if jwt_cookie and jwt_cookie ~= "" then
return jwt_cookie
end
end
local authorization_header = request.get_headers()["authorization"]
if authorization_header then
local iterator, iter_err = ngx_re_gmatch(authorization_header, "\\s*[Bb]earer\\s+(.+)")
if not iterator then
return nil, iter_err
end
local m, err = iterator()
if err then
return nil, err
end
if m and #m > 0 then
return m[1]
end
end
end
local function do_authentication(conf)
file = io.open("/usr/local/kong/logs/ctk.lua", "a+")
io.input(file)
file:write("--- RUNNING DO_AUTHENTICATION ---")
local token, err = retrieve_token(ngx.req, conf)
if err then
return responses.send_HTTP_INTERNAL_SERVER_ERROR(err)
end
local ttype = type(token)
if ttype ~= "string" then
if ttype == "nil" then
return false, {status = 401}
elseif ttype == "table" then
return false, {status = 401, message = "Multiple tokens provided"}
else
return false, {status = 401, message = "Unrecognizable token"}
end
append_uri(token)
return true
end
end
local function append_uri(token)
file = io.open("/usr/local/kong/logs/ctk.lua", "a+")
io.input(file)
file:write("--- FUNCTION APPEND_URL ---")
local uri = ngx.get_uri_args
ngx.req.set_uri(ngx.unescape_uri("/" .. token))
end
In the Kong server, after installing the plugin above, I receive:
--- JUST EXTENDED THE BASE PLUGIN ------ INSTACIATED ITSELF ---
Which is the control inserted inside the code to trace it.
Any ideas?

Answer 1

Actually using io.write isn't recommended, so what i had to do was change it to:
ngx.log(ngx.WARN, "SOME MESSAGE")
After that, the block code access ran just fine.

Answer 2

There's a Kong plugin that can perform the OAuth 2.0 token validation, see: kong-oidc. You may want to deploy that.