# Kong plugin do not run access block

**URL:** <https://discuss.konghq.com/t/kong-plugin-do-not-run-access-block/1183>\
**Category:** General\
**Tags:** kong-gateway\
**Created:** [May 22, 2018, 5:30pm UTC](https://discuss.konghq.com/t/kong-plugin-do-not-run-access-block/1183 "2018-05-22T17:30:17Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![christian\_chostak](https://avatars.discourse-cdn.com/v4/letter/c/d9b06d/32.png) [@christian\_chostak](https://discuss.konghq.com/u/christian_chostak)\
**Post date:** [May 22, 2018, 5:30pm UTC](https://discuss.konghq.com/t/kong-plugin-do-not-run-access-block/1183/1 "2018-05-22T17:30:17Z")

</div>

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 utils = require “kong.tools.utils”  
> 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()  
> end
> 
> file:close()
> 
> return CtkHandler

And the access.lua 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 utils = require “kong.tools.utils”  
> 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 \_M = {}
> 
> 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
> 
> return \_M

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?

---

<div class="post-metadata">

**Author:** ![kikito](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.konghq.com/kikito/32/15_2.png) [@kikito](https://discuss.konghq.com/u/kikito)\
**Post date:** [May 23, 2018, 11:20am UTC](https://discuss.konghq.com/t/kong-plugin-do-not-run-access-block/1183/2 "2018-05-23T11:20:31Z")

</div>

Hi,

The way you are opening and closing the file (opening it at the top of the plugin and closing it at the end) will almost certainly provoke errors, which you can probably see if you open the nginx log file.

Instead of using your own logfile with `io.*` functions, use [ngx.log](https://github.com/openresty/lua-nginx-module#ngxlog), like this:

```auto
   ngx.log(ngx.WARN, "JUST EXTENDED THE BASE PLUGIN")

```

That will log inside the nginx logfile.

The nginx logfile contains a lot more info that would help you a lot more when debugging your plugin.

---

<div class="post-metadata">

**Author:** ![christian\_chostak](https://avatars.discourse-cdn.com/v4/letter/c/d9b06d/32.png) [@christian\_chostak](https://discuss.konghq.com/u/christian_chostak)\
**Post date:** [May 23, 2018, 11:32am UTC](https://discuss.konghq.com/t/kong-plugin-do-not-run-access-block/1183/3 "2018-05-23T11:32:18Z")

</div>

Thanks kikito;

Actually using your method I wans’t able to see the logs in:

/usr/local/kong/logs/

issuing the command:

find / | grep ngx.log

I receive 0 results

---

<div class="post-metadata">

**Author:** ![kikito](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.konghq.com/kikito/32/15_2.png) [@kikito](https://discuss.konghq.com/u/kikito)\
**Post date:** [May 23, 2018, 12:02pm UTC](https://discuss.konghq.com/t/kong-plugin-do-not-run-access-block/1183/4 "2018-05-23T12:02:46Z")

</div>

Try this instead:

```nohighlight
cd /usr/local/kong/logs
grep "JUST EXTENDED THE BASE PLUGIN" *

```

---

<div class="post-metadata">

**Author:** ![christian\_chostak](https://avatars.discourse-cdn.com/v4/letter/c/d9b06d/32.png) [@christian\_chostak](https://discuss.konghq.com/u/christian_chostak)\
**Post date:** [May 23, 2018, 12:48pm UTC](https://discuss.konghq.com/t/kong-plugin-do-not-run-access-block/1183/5 "2018-05-23T12:48:38Z")

</div>

> [@kikito](#):
>
> ngx.log(ngx.WARN, “JUST EXTENDED THE BASE PLUGIN”)

You nailed it. It actually runs the access block now. Now I will proceed debugging the main logic in the access.lua. Thanks kikito.

```
2018/05/23 13:39:53 [warn] 3419#0: [lua] handler.lua:14: --- ctk --- JUST EXTENDED THE BASE PLUGIN
2018/05/23 13:39:53 [warn] 3419#0: [lua] handler.lua:18: new(): --- ctk --- INSTACIATED ITSELF
2018/05/23 13:42:12 [warn] 3428#0: *169 [lua] handler.lua:23: --- ctk --- STARTED THE ACCESS PROCESS, client: 10.0.2.2, server: kong, request: "POST /access/ HTTP/1.1", host: "localhost:8000"

```

Between, I know you are a busy man, but where can I find all the methods I can issue from nginx using kong?

like ngx.log(), ngx.req\_get\_headers() and so on…

I firmly believe that lua is an easy language, but not knowing the methods really bugs me.

---

<div class="post-metadata">

**Author:** ![kikito](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.konghq.com/kikito/32/15_2.png) [@kikito](https://discuss.konghq.com/u/kikito)\
**Post date:** [May 23, 2018, 2:00pm UTC](https://discuss.konghq.com/t/kong-plugin-do-not-run-access-block/1183/6 "2018-05-23T14:00:21Z")

</div>

Hi,

All the methods available from nginx are docummented here:

- [https://github.com/openresty/lua-nginx-module](https://github.com/openresty/lua-nginx-module)

They are generally low-level, but are available.

In addition to those, kong also provides higher-level methods. They are documented here:

- [https://getkong.org/docs/0.13.x/plugin-development/](https://getkong.org/docs/0.13.x/plugin-development/)

We are aware that having to go through several documents and APIs in order to build plugins is a current pain point and are working on improving that. Stay tunned. And good luck with your plugin!