Invalid node type panic when implementing plugin for KrakenD

#php editor Baicao today introduces to you a common problem in the development of KrakenD plug-ins: "Invalid node type panic when implementing plug-ins for KrakenD". KrakenD is a fast, high-performance API gateway that provides rich functionality and a flexible plug-in system. However, when developing a KrakenD plug-in, you sometimes encounter the problem of invalid node types, which may cause the plug-in to fail to function properly. In this article, we will explore the causes of this problem and solutions to help developers overcome this panic.

Question content

I am developing a plugin without redirection. I'm using krakend-ce 2.2.1 (using golang 1.19) and I'm panicking:

gw_krakend_1  | [krakend] 2023/03/15 - 21:09:06.675 ? debug no_redirect_plugin: request received https://127.0.0.1:8443/abc
gw_krakend_1  | [krakend] 2023/03/15 - 21:09:06.689 ? debug no_redirect_plugin: redirect detected https://127.0.0.1:8443/abc
gw_krakend_1  | [krakend] 2023/03/15 - 21:09:06.689 ? debug status code 302
gw_krakend_1  | 2023/03/15 21:09:06 http: panic serving [::1]:54778: invalid node type
gw_krakend_1  | goroutine 84 [running]:
gw_krakend_1  | net/http.(*conn).serve.func1()
gw_krakend_1  |         /usr/local/go/src/net/http/server.go:1854 +0xbf
gw_krakend_1  | panic({0x28cbb60, 0x34b5810})
gw_krakend_1  |         /usr/local/go/src/runtime/panic.go:890 +0x263
gw_krakend_1  | github.com/gin-gonic/gin.(*node).findcaseinsensitivepathrec(0x0?, {0xc0016ac2ec?, 0x0?}, {0xc0010fe800?, 0xc0016ac2ed?, 0xc000ced928?}, {0x0, 0x0, 0x0, 0x0}, ...)
gw_krakend_1  |         /go/pkg/mod/github.com/gin-gonic/[email protected]/tree.go:862 +0xa9d
gw_krakend_1  | github.com/gin-gonic/gin.(*node).findcaseinsensitivepath(0xc0016ac2ec?, {0xc0016ac2ec, 0x5}, 0x30?)
gw_krakend_1  |         /go/pkg/mod/github.com/gin-gonic/[email protected]/tree.go:669 +0x9c
gw_krakend_1  | github.com/gin-gonic/gin.redirectfixedpath(0xc000664300, 0xc0016ac2ec?, 0x60?)
gw_krakend_1  |         /go/pkg/mod/github.com/gin-gonic/[email protected]/gin.go:684 +0x5b
gw_krakend_1  | github.com/gin-gonic/gin.(*engine).handlehttprequest(0xc000602b60, 0xc000664300)

Looks similar to it https://github.com/gin-gonic/gin/issues/2959, but the version of gin has been upgraded on the previous version of krakend. It would be weird if they were really capital letters, it works perfectly without the plugin. I also trimmed the last / (it was added at some point for some reason)

BTW, I'm using the same version of krakend to compile the plugin.

package main

import (
    "context"
    "errors"
    "fmt"
    "io"
    "net/http"
    "net/url"
    "strings"
)

func main() {}

var clientregisterer = registerer("no_redirect_plugin")

type registerer string

type logger interface {
    debug(v ...interface{})
    info(v ...interface{})
    warning(v ...interface{})
    error(v ...interface{})
    critical(v ...interface{})
    fatal(v ...interface{})
}

var logger logger = nil

func (registerer) registerlogger(v interface{}) {
    l, ok := v.(logger)
    if !ok {
        return
    }
    logger = l
    logger.info(fmt.sprintf("[plugin: %s] logger loaded", clientregisterer))
}

func (r registerer) registerclients(f func(
    name string,
    handler func(context.context, map[string]interface{}) (http.handler, error),
)) {
    f(string(r), r.registerclients)
}

func (r registerer) registerclients(_ context.context, extra map[string]interface{}) (http.handler, error) {
    name, ok := extra["name"].(string)
    if !ok {
        return nil, errors.new("wrong config")
    }

    if name != string(r) {
        return nil, fmt.errorf("unknown register %s", name)
    }

    httpclient := &http.client{
        checkredirect: func(req *http.request, via []*http.request) error {

            // trim the last "/" character from the url if it exists
            urlstr := strings.trimright(req.url.string(), "/")
            req.url, _ = url.parse(urlstr)

            logger.debug("no_redirect_plugin: redirect detected", req.url.string())
            return http.erruselastresponse
        },
    }

    return http.handlerfunc(func(w http.responsewriter, req *http.request) {

        // trim the last "/" character from the url if it exists
        urlstr := strings.trimright(req.url.string(), "/")
        req.url, _ = url.parse(urlstr)

        logger.debug("no_redirect_plugin: request received", req.url.string())
        resp, err := httpclient.do(req)
        if err != nil {
            logger.debug("error while proxying request", err.error())
            http.error(w, err.error(), http.statusinternalservererror)
            return
        }

        defer resp.body.close()

        for k, hs := range resp.header {
            for _, h := range hs {
                w.header().add(k, h)
            }
        }

        w.writeheader(resp.statuscode)
        logger.debug("status code", resp.statuscode)
        if resp.body == nil {
            return
        }

        _, err = io.copy(w, resp.body)
        if err != nil {
            logger.debug("error while proxying request 2", err.error())
            http.error(w, err.error(), http.statusinternalservererror)
            return
        }

    }), nil
}

My endpoint is defined as follows:

{
     "endpoint": "/",
     "input_headers":[
       "*"
     ],
     "input_query_strings":[
       "*"
     ],
     "method": "GET",
     "output_encoding": "no-op",
     "extra_config": {},
     "backend": [{
       "url_pattern": "",
       "encoding": "no-op",
       "sd": "static",
       "method": "GET",
       "extra_config": {
         "plugin/http-client": {
           "name": "no_redirect_plugin"
         }
       },
       "host": [
         "{{ env "HOST" }}"
       ],
       "disable_host_sanitize": false
   }]
},{
     "endpoint": "/{level1}",
     "input_headers":[
       "*"
     ],
     "input_query_strings":[
       "*"
     ],
     "method": "GET",
     "output_encoding": "no-op",
     "extra_config": {
     },
     "backend": [{
       "url_pattern": "/{level1}",
       "encoding": "no-op",
       "sd": "static",
       "method": "GET",
       "extra_config": {
         "plugin/http-client": {
           "name": "no_redirect_plugin"
         }
       },
       "host": [
         "{{ env "HOST" }}"
       ],
       "disable_host_sanitize": false
   }]
},{
     "endpoint": "/{level1}/{level2}",
     "input_headers":[
       "*"
     ],
     "input_query_strings":[
       "*"
     ],
     "method": "GET",
     "output_encoding": "no-op",
     "extra_config": {
     },
     "backend": [{
       "url_pattern": "/{level1}/{level2}",
       "encoding": "no-op",
       "sd": "static",
       "method": "GET",
       "extra_config": {
         "plugin/http-client": {
           "name": "no_redirect_plugin"
         }
       },
       "host": [
         "{{ env "HOST" }}"
       ],
       "disable_host_sanitize": false
   }]
}

EDIT: My browser still shows /abc/ instead of /abc, which could create possible collisions between routes (as seen here: https://github.com/krakendio/krakend-ce/issues /386) Anyway I don't know where to add the slash (I thought I trimmed it permanently...seems like I didn't)

edit2: I found this https://www.krakend.io/docs/service-settings/router-options/ and used "disable_redirect_fixed_path": true and "disable_redirect_trailing_slash": true, it doesn't panic anymore... Now I have another problem: infinite redirects (just 10 just kidding) when my boulder tries to redirect to /a/ or anything with a trailing slash This is done in the plugin because krakend used to handle redirects in its own way...

I guess the main problem here is routing conflict, when /{level1} and /{level1}/{level2} match /abc/ at the same time

idea?

Solution

Very good, in order to solve this problem, I tried to use this to create a wildcard no_redirect plug-in https://www.php.cn/link/ba530cdf0a884348613f2aaa3a5ba5e8 configuration, but even with copilot&gpt4 I failed, I dare say you can implement this. So I solved the problem with another way: I put the gateway in front of my boulder and every time the request failed I added the route... because we didn't have a logged route (*sobs). It works just fine for files that require a redirect-free plugin. A great solution but it has worked so far and not as long as I thought

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