OCPBUGS-27210: Restore HTTP/2 tests in test/extended/router

test/extended/router/http2.go

@@ -38,22 +38,39 @@ const (
 	http2ClientTimeout = 1 * time.Minute
 )
 
+// makeHTTPClient creates a new HTTP client, configurable for timeout
+// duration and optional HTTP/2 support.
+//
+// When useHTTP2Transport is true, the function enables HTTP/2 support
+// via http2.ConfigureTransport, modifying the http.Transport to
+// support HTTP/2 with a fallback to HTTP/1.1. If useHTTP2Transport is
+// false, the client defaults to HTTP/1.1. The protocol selection
+// between HTTP/2 and HTTP/1.1 occurs during the TLS handshake through
+// ALPN, defaulting to HTTP/1.1 if HTTP/2 is not mutually agreed upon.
+//
+// This client is also configured with TLS settings that skip
+// certificate verification (InsecureSkipVerify).
+//
+// The function returns a pointer to the configured http.Client.
 func makeHTTPClient(useHTTP2Transport bool, timeout time.Duration) *http.Client {
 	tlsConfig := tls.Config{
 		InsecureSkipVerify: true,
 	}
 
+	transport := &http.Transport{
+		TLSClientConfig: &tlsConfig,
+	}
+
 	c := &http.Client{
-		Timeout: timeout,
-		Transport: &http.Transport{
-			TLSClientConfig: &tlsConfig,
-		},
+		Timeout:   timeout,
+		Transport: transport,
 	}
 
+	// If HTTP/2 is to be used, configure it to allow falling back
+	// to HTTP/1.1
 	if useHTTP2Transport {
-		c.Transport = &http2.Transport{
-			TLSClientConfig: &tlsConfig,
-		}
+		// Explicitly allow HTTP/2.
+		http2.ConfigureTransport(transport)
 	}
 
 	return c
@@ -408,6 +425,18 @@ var _ = g.Describe("[sig-network-edge][Conformance][Area:Networking][Feature:Rou
 				backendProto:      "HTTP/2.0",
 				statusCode:        http.StatusOK,
 				useHTTP2Transport: true,
+			}, {
+				route:             "http2-default-cert-edge",
+				statusCode:        http.StatusOK,
+				frontendProto:     "HTTP/1.1",
+				backendProto:      "HTTP/1.1",
+				useHTTP2Transport: true,
+			}, {
+				route:             "http2-default-cert-reencrypt",
+				statusCode:        http.StatusOK,
+				frontendProto:     "HTTP/1.1",
+				backendProto:      "HTTP/2.0", // reencrypt always has backend ALPN enabled
+				useHTTP2Transport: true,
 			}, {
 				route:             "http2-custom-cert-edge",
 				frontendProto:     "HTTP/1.1",