Server Plugin on Documentation does not work?

[Alberto Garcia Taravillo]

Hi,

I'm following documentation to include a dummy handler plugin, it gets loaded but seems the handler does not execute never
This is the main.go file:
examples/plugins/handler at main · krakend/examples · GitHub

My config:
{
   "version": 3,
   "plugin": {
      "pattern": ".so",
      "folder": "/etc/krakend/plugins"
   },
   "host": ["http://localhost:8080/"],
   "debug_endpoint": true,
   "endpoints": [
      {
         "endpoint": "/example",
         "backend": [
            {
               "url_pattern": "/__debug/"
            }
         ]
      }
   ],
   "extra_config": {
      "plugin/http-server": {
         "name": ["my-handler-plugin"],
         "my-handler-plugin": {
            "someOption": "some-value"
         }
      }
   }
}

And the logs shows the plugin is correctly loaded but if you pay attention the log message when the options are being read does not appear

2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND INFO: Starting KrakenD v2.8.0
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND INFO: Working directory is /etc/krakend
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND DEBUG: [SERVICE: Plugin Loader] Starting loading process
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND DEBUG: [SERVICE: Executor Plugin] plugin #0 (/etc/krakend/plugins/krakend-server-example.so): plugin: symbol ClientRegisterer not found in plugin krakend-server-example
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND DEBUG: [PLUGIN: my-handler-plugin] Example handler plugin loaded
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND INFO: [SERVICE: Handler Plugin] Total plugins loaded: 1
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND DEBUG: [SERVICE: Modifier Plugin] plugin #0 (/etc/krakend/plugins/krakend-server-example.so): plugin: symbol ModifierRegisterer not found in plugin krakend-server-example
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND DEBUG: [SERVICE: Plugin Loader] Loading process completed
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND INFO: Starting the KrakenD instance
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND DEBUG: [ENDPOINT: /test/:id] Building the proxy pipe
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND DEBUG: [BACKEND: /__health] Building the backend pipe
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND DEBUG: [ENDPOINT: /test/:id] Building the http handler
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND DEBUG: [ENDPOINT: /test/:id][JWTSigner] Signer disabled
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND INFO: [ENDPOINT: /test/:id][JWTValidator] Validator disabled for this endpoint
2025-04-10 16:46:42 2025/04/10 14:46:42 KRAKEND INFO: [SERVICE: Gin] Listening on port: 8080
2025-04-10 16:46:47 2025/04/10 14:46:47 KRAKEND DEBUG: [SERVICE: Telemetry] Registering usage stats for Cluster ID PYlBFoSGeuCKjqWCCBiZwD9b3H3oJBhuMooDDlpQBD0=
2025-04-10 16:46:42 Parsing configuration file: /etc/krakend/krakend.json
2025-04-10 16:46:49 [GIN] 2025/04/10 - 14:46:49 | 404 |       4.617µs |      172.18.0.1 | GET      "/example  "


The file .so it's on the folder.

the dockerfile used

FROM krakend/builder:2.8.0 AS krakend-server-example

COPY ./plugins/krakend-server-example /app/krakend-server-example

WORKDIR /app/krakend-server-example

RUN go mod tidy

RUN go build -buildmode=plugin -o krakend-server-example.so .

FROM devopsfaith/krakend:2.8.0

COPY --from=krakend-server-example /app/krakend-server-example/krakend-server-example.so /etc/krakend/plugins/krakend-server-example.so

Any suggestion? is something missing in the docs?

Thanks

[Daniel Ortiz]

Hi Alberto,

If you check the code, you will see the option is called "option". Will fix the generic example to avoid confusion.

Best regards.

[Alberto Garcia Taravillo]

Hi,

Thanks for you reply :)

Sorry the doc is ok, no need to update anything. I just copy/paste the extra config from the comment that seems to be deprecated, my bad. 

In any case....
Copy/paste all the files from the example: handler.go, krakend.json and then build with the dockerfile shown and the handler does not reach. The *.so file is placed into the folder. 
If there's an error in the options I assume the message fmt.Errorf("%s plugin disabled: config not found", pluginName) would appear but does not . 

I've added even a debug message at the start of the handler:

func (r registerer) registerHandlers(_ context.Context, extra map[string]interface{}, h http.Handler) (http.Handler, error) {

    logger.Debug("Handler executing...")

   

It's like handler does not execute.
Any reason for this behaviour? Something that helps to identify the root cause? 

2025-04-10 18:11:05 Parsing configuration file: /etc/krakend/krakend.json
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND INFO: Starting KrakenD v2.8.0
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND INFO: Working directory is /etc/krakend
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND DEBUG: [SERVICE: Plugin Loader] Starting loading process
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND DEBUG: [SERVICE: Executor Plugin] plugin #0 (/etc/krakend/plugins/krakend-server-example.so): plugin: symbol ClientRegisterer not found in plugin krakend-server-example
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND DEBUG: [PLUGIN: my-handler-plugin] Example handler plugin loaded
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND INFO: [SERVICE: Handler Plugin] Total plugins loaded: 1
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND DEBUG: [SERVICE: Modifier Plugin] plugin #0 (/etc/krakend/plugins/krakend-server-example.so): plugin: symbol ModifierRegisterer not found in plugin krakend-server-example
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND DEBUG: [SERVICE: Plugin Loader] Loading process completed
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND DEBUG: [SERVICE: Gin] Debug enabled
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND INFO: Starting the KrakenD instance
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND DEBUG: [ENDPOINT: /example] Building the proxy pipe
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND DEBUG: [BACKEND: /__debug/] Building the backend pipe
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND DEBUG: [ENDPOINT: /example] Building the http handler
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND DEBUG: [ENDPOINT: /example][JWTSigner] Signer disabled
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND INFO: [ENDPOINT: /example][JWTValidator] Validator disabled for this endpoint
2025-04-10 18:11:05 2025/04/10 16:11:05 KRAKEND INFO: [SERVICE: Gin] Listening on port: 8080
2025-04-10 18:11:10 2025/04/10 16:11:10 KRAKEND DEBUG: [ENDPOINT: /__debug/*] Method: GET
2025-04-10 18:11:10 2025/04/10 16:11:10 KRAKEND DEBUG: [ENDPOINT: /__debug/*] URL: /__debug/
2025-04-10 18:11:10 2025/04/10 16:11:10 KRAKEND DEBUG: [ENDPOINT: /__debug/*] Query: map[]
2025-04-10 18:11:10 2025/04/10 16:11:10 KRAKEND DEBUG: [ENDPOINT: /__debug/*] Params: [{param /}]
2025-04-10 18:11:10 2025/04/10 16:11:10 KRAKEND DEBUG: [ENDPOINT: /__debug/*] Headers: map[Accept-Encoding:[gzip] Content-Type:[application/json] User-Agent:[KrakenD Version 2.8.0] X-Forwarded-For:[172.18.0.1] X-Forwarded-Host:[localhost:8080]]
2025-04-10 18:11:10 2025/04/10 16:11:10 KRAKEND DEBUG: [ENDPOINT: /__debug/*] Body:
2025-04-10 18:11:10 [GIN] 2025/04/10 - 16:11:10 | 200 |     136.766µs |      172.18.0.1 | GET      "/__debug/"
2025-04-10 18:11:10 [GIN] 2025/04/10 - 16:11:10 | 200 |    1.415593ms |      172.18.0.1 | GET      "/example"
2025-04-10 18:11:10 2025/04/10 16:11:10 KRAKEND DEBUG: [SERVICE: Telemetry] Registering usage stats for Cluster ID Zjh/2gxYqjR+LNfnK40zwytAmZMxcbteUqhUuaOcR1E=

[David Hontecillas]

Also, the name of the plugin is "krakend-server-example", and in your config you are using "my-handler-plugin" . 

Try to change the config to match the name of the plugin.

[Alberto Garcia Taravillo]

My bad.
There was a lot of bad copy/paste