Read header added by Queue-proxy in Activator

[bonavadeur]

Hi all, I am working with Knative Serving. I modified the Queue-Proxy successfully to add some extra headers into HTTP packet response from Application Pod back to Activator. The extra-headers I added into HTTP response from queue-proxy can be captured in Wireshark. Now, how can I read this header in Activator side? Where is the codes in Activator that receive HTTP response from queue-proxy back to Activator?

Thanks for helps ❤️

[skonto]

Hi @bonavadeur, we proxy the request here. You could use something like the following:

diff --git a/pkg/activator/handler/handler.go b/pkg/activator/handler/handler.go
index 74acbb7ed..6a9fea58d 100644
--- a/pkg/activator/handler/handler.go
+++ b/pkg/activator/handler/handler.go
@@ -19,6 +19,7 @@ package handler
 import (
 	"context"
 	"errors"
+	"fmt"
 	"net/http"
 	"net/http/httputil"
 	"strconv"
@@ -140,10 +141,18 @@ func (a *activationHandler) proxyRequest(revID types.NamespacedName, w http.Resp
 	proxy.ErrorHandler = func(w http.ResponseWriter, req *http.Request, err error) {
 		pkghandler.Error(a.logger.With(zap.String(logkey.Key, revID.String())))(w, req, err)
 	}
+	proxy.ModifyResponse = UpdateResponse
 
 	proxy.ServeHTTP(w, r)
 }
 
+func UpdateResponse(r *http.Response) error {
+	for k, v := range r.Header {
+		fmt.Println(k, "value is", v)
+	}
+	return nil
+}
+
 // useSecurePort replaces the default port with HTTPS port (8112).
 // TODO: endpointsToDests() should support HTTPS instead of this overwrite but it needs metadata request to be encrypted.
 // This code should be removed when https://github.com/knative/serving/issues/12821 was solved.

This prints:

Content-Length value is [20]
Content-Type value is [text/plain; charset=utf-8]
Date value is [Tue, 26 Nov 2024 11:18:57 GMT]