fix: don't stary Otel when no configuration

cmd/relayproxy/api/server.go

@@ -119,10 +119,12 @@ func (s *Server) Start() {
 	}
 
 	// start the OpenTelemetry tracing service
-	err := s.otelService.Init(context.Background(), *s.config)
-	if err != nil {
-		s.zapLog.Error("error while initializing Otel", zap.Error(err))
-		// we can continue because otel is not mandatory to start the server
+	if s.config.OpenTelemetryOtlpEndpoint != "" {
+		err := s.otelService.Init(context.Background(), *s.config)
+		if err != nil {
+			s.zapLog.Error("error while initializing Otel", zap.Error(err))
+			// we can continue because otel is not mandatory to start the server
+		}
 	}
 
 	// starting the main application
@@ -135,7 +137,7 @@ func (s *Server) Start() {
 		zap.String("address", address),
 		zap.String("version", s.config.Version))
 
-	err = s.apiEcho.Start(address)
+	err := s.apiEcho.Start(address)
 	if err != nil && !errors.Is(err, http.ErrServerClosed) {
 		s.zapLog.Fatal("Error starting relay proxy", zap.Error(err))
 	}