Add Techulus host response header

agent/internal/traefik/l4.go

@@ -49,7 +49,10 @@ func CompileRoutes(httpRoutes []TraefikRoute, tcpRoutes []TraefikTCPRoute, udpRo
 	}
 	var middlewareNames []string
 	if serverName != "" {
-		config.HTTP.Middlewares["forwarded_server"] = middleware{Headers: &headersMiddleware{CustomRequestHeaders: map[string]string{"X-Forwarded-Server": serverName}}}
+		config.HTTP.Middlewares["forwarded_server"] = middleware{Headers: &headersMiddleware{
+			CustomRequestHeaders:  map[string]string{"X-Forwarded-Server": serverName},
+			CustomResponseHeaders: map[string]string{"X-Techulus-Host": serverName},
+		}}
 		middlewareNames = []string{"forwarded_server@file"}
 	}
 	for _, route := range httpRoutes {

agent/internal/traefik/routes_test.go

@@ -84,6 +84,9 @@ func TestRoutesConfigRoundTripProducesConvergentHash(t *testing.T) {
 	if forwardedServer.Headers == nil || forwardedServer.Headers.CustomRequestHeaders["X-Forwarded-Server"] != "proxy-1" {
 		t.Fatalf("forwarded server middleware was not preserved: %#v", forwardedServer)
 	}
+	if forwardedServer.Headers.CustomResponseHeaders["X-Techulus-Host"] != "proxy-1" {
+		t.Fatalf("Techulus host response header was not preserved: %#v", forwardedServer)
+	}
 	tcpRouter := config.TCP.Routers[resourceName("tcp", "service-tcp", "tcp-route")]
 	if tcpRouter.TLS == nil || !tcpRouter.TLS.Passthrough {
 		t.Fatalf("TCP TLS passthrough was not preserved: %#v", tcpRouter)

agent/internal/traefik/types.go

@@ -69,7 +69,8 @@ type middleware struct {
 }
 
 type headersMiddleware struct {
-	CustomRequestHeaders map[string]string `yaml:"customRequestHeaders,omitempty"`
+	CustomRequestHeaders  map[string]string `yaml:"customRequestHeaders,omitempty"`
+	CustomResponseHeaders map[string]string `yaml:"customResponseHeaders,omitempty"`
 }
 
 type replacePathRegex struct {