address feedback

pkg/deprecated_header.go

@@ -67,14 +67,7 @@ const (
 	// different user-agent.  So we augment the probes with this header.
 	//
 	// Deprecated: use knative.dev/networking/pkg/http/header.UserAgentKey
-	KubeletProbeHeaderName = header.UserAgentKey
-
-	// KubeletProbeKey is the name of the header supplied by kubelet
-	// probes.  Istio with mTLS rewrites probes, but their probes pass a
-	// different user-agent.  So we augment the probes with this header.
-	//
-	// Deprecated: use knative.dev/networking/pkg/http/header.UserAgentKey
-	KubeletProbeKey = header.UserAgentKey
+	KubeletProbeHeaderName = header.KubeletProbeKey
 
 	// UserAgentKey is the constant for header "User-Agent".
 	//

pkg/http/header/header.go

@@ -55,11 +55,14 @@ const (
 	// at the Queue proxy level back to be a host header.
 	OriginalHostKey = "K-Original-Host"
 
-	// KubeletProbeKey is the name of the header supplied by kubelet
-	// probes.  Istio with mTLS rewrites probes, but their probes pass a
-	// different user-agent.  So we augment the probes with this header.
+	// KubeletProbeKey is the name of the header supplied by kubelet probes.
+	// Prior to this deprecation, Istio with mTLS rewrote probes and their probes passed a
+	// different user-agent.  Therefore, this header was added to augment the probes.
 	//
-	// Deprecated: use knative.dev/networking/pkg/http/header.UserAgentKey
+	// Deprecated: this custom request header is no longer necessary since Istio now propagates the
+	// original request header `User-Agent` sent by the kubelet (e.g., User-Agent: kube-probe/1.29).
+	// For updated usage, please utilize knative.dev/networking/pkg/http/header.UserAgentKey and
+	// knative.dev/networking/pkg/http/header.KubeProbeUAPrefix
 	KubeletProbeKey = "K-Kubelet-Probe"
 
 	// RouteTagKey is the name of the header entry which has a tag name as value.
@@ -128,7 +131,8 @@ func IsProbe(r *http.Request) bool {
 
 // IsKubeletProbe returns true if the request is a Kubernetes probe.
 func IsKubeletProbe(r *http.Request) bool {
-	return strings.HasPrefix(r.Header.Get("User-Agent"), KubeProbeUAPrefix)
+	return strings.HasPrefix(r.Header.Get("User-Agent"), KubeProbeUAPrefix) ||
+		r.Header.Get(KubeletProbeKey) != ""
 }
 
 // RewriteHostIn removes the `Host` header from the inbound (server) request

pkg/http/header/header_test.go

@@ -38,6 +38,10 @@ func TestIsKubeletProbe(t *testing.T) {
 	if IsKubeletProbe(req) {
 		t.Error("Not a kubelet probe but counted as such")
 	}
+	req.Header.Set(KubeletProbeKey, "no matter")
+	if !IsKubeletProbe(req) {
+		t.Error("kubelet probe but not counted as such")
+	}
 }
 
 func TestKnativeProbeHeader(t *testing.T) {