Add REST GET /config endpoint to fetch agent configuration

_codeql_detected_source_root

@@ -0,0 +1 @@
+.

src/mtconnect/sink/rest_sink/rest_service.cpp

@@ -19,6 +19,8 @@
 
 #include <regex>
 
+#include <nlohmann/json.hpp>
+
 #include "error.hpp"
 #include "mtconnect/configuration/config_options.hpp"
 #include "mtconnect/entity/xml_parser.hpp"
@@ -118,6 +120,7 @@ namespace mtconnect {
       createAssetRoutings();
       createProbeRoutings();
       createPutObservationRoutings();
+      createConfigRoutings();
       createFileRoutings();
       m_server->addCommands();
 
@@ -435,6 +438,77 @@ namespace mtconnect {
       session->writeResponse(std::move(response));
     }
 
+    void RestService::createConfigRoutings()
+    {
+      using namespace rest_sink;
+      using json = nlohmann::json;
+
+      auto handler = [this](SessionPtr session, const RequestPtr request) -> bool {
+        // Build JSON response with agent configuration
+        json config;
+
+        for (const auto& [key, value] : m_options)
+        {
+          // Handle different variant types
+          std::visit([&config, &key](auto&& arg) {
+            using T = std::decay_t<decltype(arg)>;
+            if constexpr (std::is_same_v<T, std::monostate>)
+            {
+              config[key] = nullptr;
+            }
+            else if constexpr (std::is_same_v<T, bool>)
+            {
+              config[key] = arg;
+            }
+            else if constexpr (std::is_same_v<T, int>)
+            {
+              config[key] = arg;
+            }
+            else if constexpr (std::is_same_v<T, double>)
+            {
+              config[key] = arg;
+            }
+            else if constexpr (std::is_same_v<T, std::string>)
+            {
+              config[key] = arg;
+            }
+            else if constexpr (std::is_same_v<T, Seconds>)
+            {
+              config[key] = arg.count();
+            }
+            else if constexpr (std::is_same_v<T, Milliseconds>)
+            {
+              config[key] = arg.count();
+            }
+            else if constexpr (std::is_same_v<T, StringList>)
+            {
+              config[key] = arg;
+            }
+            else
+            {
+              // If compilation fails here, a new type has been added to ConfigOption
+              // and needs to be handled above
+              []<bool flag = false>()
+              {
+                static_assert(flag, "Unhandled type in ConfigOption variant");
+              }();
+            }
+          }, value);
+        }
+
+        ResponsePtr response = make_unique<Response>(
+            rest_sink::status::ok, config.dump(), "application/json");
+        respond(session, std::move(response), request->m_requestId);
+        return true;
+      };
+
+      m_server
+          ->addRouting({boost::beast::http::verb::get, "/config", handler})
+          .document("Agent configuration request",
+                    "Returns the current agent configuration as JSON")
+          .command("config");
+    }
+
     void RestService::createFileRoutings()
     {
       using namespace rest_sink;

src/mtconnect/sink/rest_sink/rest_service.hpp

@@ -346,6 +346,8 @@ namespace mtconnect {
 
       void createAssetRoutings();
 
+      void createConfigRoutings();
+
       // Current Data Collection
       std::string fetchCurrentData(const printer::Printer *printer, const FilterSetOpt &filterSet,
                                    const std::optional<SequenceNumber_t> &at, bool pretty = false,

test_package/agent_test.cpp

@@ -29,6 +29,8 @@
 #include <stdexcept>
 #include <thread>
 
+#include <nlohmann/json.hpp>
+
 #include "agent_test_helper.hpp"
 #include "mtconnect/agent.hpp"
 #include "mtconnect/asset/file_asset.hpp"
@@ -2622,3 +2624,29 @@ TEST_F(AgentTest, should_initialize_observaton_to_initial_value_when_available)
     ASSERT_XML_PATH_EQUAL(doc, "//m:DeviceStream//m:PartCount", "0");
   }
 }
+
+TEST_F(AgentTest, should_return_agent_configuration)
+{
+  m_agentTestHelper->createAgent("/samples/test_config.xml", 8, 4, "2.6", 4, false);
+
+  // Test the /config endpoint
+  auto session = m_agentTestHelper->m_server->createSession(m_agentTestHelper->m_context);
+  auto request = make_unique<Request>("/config", boost::beast::http::verb::get);
+
+  auto routing = m_agentTestHelper->m_server->getRouting(request->m_path, request->m_verb);
+  ASSERT_TRUE(routing);
+
+  routing->m_handler(session, std::move(request));
+
+  // Verify response is JSON
+  ASSERT_EQ(session->m_mimeType, "application/json");
+  ASSERT_EQ(session->m_code, boost::beast::http::status::ok);
+
+  // Parse JSON response
+  auto json = nlohmann::json::parse(session->m_body);
+
+  // Verify key configuration values are present
+  ASSERT_TRUE(json.contains("Port"));
+  ASSERT_TRUE(json.contains("BufferSize"));
+  ASSERT_TRUE(json.contains("SchemaVersion"));
+}