Unable to read requestContext data from event in fiber

[Shahab96]

I'm currently using fiber for my app and have a handler which will be given data passed through by a custom auth lambda. I am unable to access the lambda event from within my handler however. I'm currently using ProxyWithContextV2 to run my app, but I can't seem to find a way to extract the event data from within the handler.

func init() {
	log.Printf("Cold start.")

	app = fiber.New()

	app.Post("/auth/login", routes.Login)
	app.Post("/auth/register", routes.Register)
	app.Post("/auth/logout", routes.Logout)
	fiberLambda = fiberadapter.New(app)
}

func handler(ctx context.Context, req events.APIGatewayV2HTTPRequest) (events.APIGatewayV2HTTPResponse, error) {
	return fiberLambda.ProxyWithContextV2(ctx, req)
}

func main() {
	if os.Getenv("AWS_EXECUTION_ENV") == "AWS_Lambda_go1.x" {
		lambda.Start(handler)
	} else {
		app.Listen(":3000")
	}
}

func Logout(c *fiber.Ctx) error {
  // Need to get the event.requestContext.authorizer here
}

[kasperbe]

I am currently running in to the same problem using the negroni adapter.

I have come to the conclusion that there's a problem with ProxyWithContext.
It seems the requestContext is not added to the request.

If you're willing to give up the request context you can use fiberLambda.Proxy, however this is not a real solution.

To bypass this for now we can add the requestContext to the context manully:

    return fiberLambda.ProxyWithContext(context.WithValue(ctx, requestContext, req.RequestContext), req)

And in your handler, access the requestContext using:

    reqCtx := req.Context().Value(RequestContext)

@sapessi (Sorry for the direct tag) is this inteded, and if not, I could provide a fix to add the requestContext on the ProxyWithContext.
What do you think? :)

[esoteloferry]

Hi @Shahab96 , I am using same setup Fiber+HTTP(v2) gateway + aws-lambda-go-api-proxy v0.14.0.

I implemented a Post /auth/login endpoint as dummy endpoing and I am struggling with next error

{
  "statusCode": 404,
  "headers": {
    "Content-Type": "text/plain; charset=utf-8"
  },
  "multiValueHeaders": null,
  "body": "Cannot GET /",
  "cookies": []
}

All requests are pointing to GET / , I wonder if you had this issue? or you can share more details of your setup?

[seanamos]

I know this is old, but unless I'm blind, I can't see how this is supposed to work.

ProxyWithContext(V2) calls EventToRequestWithContext which creates an http.Request with the context set.
This http.Request gets passed to proxyInternal(V2), which then passes it to adapter.
All good so far.

Now this is where it seems to fall apart:
adapter constructs a fasthttp.Request from the http.Request, and a fasthttp.RequestCtx. However, the context stored in the http.Request is never used in adapter, it's never forwarded in any way to Fiber, so it is lost!

You can see this here:

aws-lambda-go-api-proxy/fiber/adapter.go

Lines 103 to 166 in 55b7779

	func (f *FiberLambda) adaptor(w http.ResponseWriter, r *http.Request) {
	// New fasthttp request
	req := fasthttp.AcquireRequest()
	defer fasthttp.ReleaseRequest(req)
	// Convert net/http -> fasthttp request
	body, err := io.ReadAll(r.Body)
	if err != nil {
	http.Error(w, utils.StatusMessage(fiber.StatusInternalServerError), fiber.StatusInternalServerError)
	return
	}
	req.Header.SetContentLength(len(body))
	_, _ = req.BodyWriter().Write(body)
	req.Header.SetMethod(r.Method)
	req.SetRequestURI(r.RequestURI)
	req.SetHost(r.Host)
	for key, val := range r.Header {
	for _, v := range val {
	switch key {
	case fiber.HeaderHost,
	fiber.HeaderContentType,
	fiber.HeaderUserAgent,
	fiber.HeaderContentLength,
	fiber.HeaderConnection:
	req.Header.Set(key, v)
	default:
	req.Header.Add(key, v)
	}
	}
	}
	// We need to make sure the net.ResolveTCPAddr call works as it expects a port
	addrWithPort := r.RemoteAddr
	if !strings.Contains(r.RemoteAddr, ":") {
	addrWithPort = r.RemoteAddr + ":80" // assuming a default port
	}
	remoteAddr, err := net.ResolveTCPAddr("tcp", addrWithPort)
	if err != nil {
	fmt.Printf("could not resolve TCP address for addr %s\n", r.RemoteAddr)
	log.Println(err)
	http.Error(w, utils.StatusMessage(fiber.StatusInternalServerError), fiber.StatusInternalServerError)
	return
	}
	// New fasthttp Ctx
	var fctx fasthttp.RequestCtx
	fctx.Init(req, remoteAddr, nil)
	// Pass RequestCtx to Fiber router
	f.app.Handler()(&fctx)
	// Set response headers
	fctx.Response.Header.VisitAll(func(k, v []byte) {
	w.Header().Add(utils.UnsafeString(k), utils.UnsafeString(v))
	})
	// Set response statuscode
	w.WriteHeader(fctx.Response.StatusCode())
	// Set response body
	_, _ = w.Write(fctx.Response.Body())
	}

At no point in that function is the context stored in the http.Request passed to Fiber.