diff --git a/cpp/src/server/ServerConfig.h b/cpp/src/server/ServerConfig.h
index f337275a4688721b2209ef07593795d8b4bf18a0..412581bc1fb36ccc7cf3de6fabdc10d807a758cc 100644
--- a/cpp/src/server/ServerConfig.h
+++ b/cpp/src/server/ServerConfig.h
@@ -43,6 +43,9 @@ static const std::string CONFIG_METRIC_COLLECTOR = "collector";
 static const std::string CONFIG_PROMETHEUS = "prometheus_config";
 static const std::string CONFIG_METRIC_PROMETHEUS_PORT = "port";
 
+static const std::string CONFIG_ENGINE = "engine_config";
+static const std::string CONFIG_NPROBE = "nprobe";
+
 class ServerConfig {
  public:
     static ServerConfig &GetInstance();