ROX-26516: Introspection endpoint for runtime config (#1879)

Author: JoukoVirtanen

collector/lib/CollectorConfigInspector.cpp

@@ -0,0 +1,55 @@
+#include "CollectorConfigInspector.h"
+
+#include <Logging.h>
+#include <string>
+
+#include <google/protobuf/util/json_util.h>
+
+namespace collector {
+
+const std::string CollectorConfigInspector::kBaseRoute = "/state/config";
+
+CollectorConfigInspector::CollectorConfigInspector(const std::shared_ptr<CollectorConfig> config) : config_(config) {
+}
+
+std::string CollectorConfigInspector::configToJson(bool& isError) {
+  const auto& runtime_config = config_->GetRuntimeConfig();
+
+  if (!runtime_config.has_value()) {
+    return "{}";
+  }
+
+  std::string jsonString;
+  const auto& config = runtime_config.value();
+  google::protobuf::util::Status status = google::protobuf::util::MessageToJsonString(config, &jsonString);
+
+  if (!status.ok()) {
+    isError = true;
+    CLOG(WARNING) << "Failed to convert protobuf object to JSON: " << status.ToString();
+    return R"({"error": "Failed to convert protobuf object to JSON")";
+  }
+
+  return jsonString;
+}
+
+bool CollectorConfigInspector::handleGet(CivetServer* server, struct mg_connection* conn) {
+  const mg_request_info* req_info = mg_get_request_info(conn);
+
+  if (req_info == nullptr) {
+    return ServerError(conn, "unable to read request");
+  }
+
+  bool isError = false;
+  std::string jsonString = configToJson(isError);
+
+  if (isError) {
+    mg_printf(conn, "HTTP/1.1 500 Internal Server Error\r\nContent-Type: application/json\r\nConnection: close\r\n\r\n");
+  } else {
+    mg_printf(conn, "HTTP/1.1 200 OK\r\nContent-Type: application/json\r\nConnection: close\r\n\r\n");
+  }
+  mg_printf(conn, "%s\r\n", jsonString.c_str());
+
+  return true;
+}
+
+}  // namespace collector

collector/lib/CollectorConfigInspector.h

@@ -0,0 +1,29 @@
+#ifndef COLLECTOR_CONFIG_INSPECTOR_H
+#define COLLECTOR_CONFIG_INSPECTOR_H
+
+#include <memory>
+
+#include <json/writer.h>
+
+#include "CollectorConfig.h"
+#include "IntrospectionEndpoint.h"
+
+namespace collector {
+
+class CollectorConfigInspector : public IntrospectionEndpoint {
+ public:
+  static const std::string kBaseRoute;
+
+  CollectorConfigInspector(const std::shared_ptr<CollectorConfig> config);
+
+  // implementation of CivetHandler
+  bool handleGet(CivetServer* server, struct mg_connection* conn) override;
+
+ private:
+  const std::shared_ptr<CollectorConfig> config_;
+  std::string configToJson(bool& isError);
+};
+
+}  // namespace collector
+
+#endif

collector/lib/CollectorService.cpp

@@ -10,6 +10,7 @@ extern "C" {
 #include <memory>
 
 #include "CivetServer.h"
+#include "CollectorConfigInspector.h"
 #include "CollectorStatsExporter.h"
 #include "ConnTracker.h"
 #include "Containers.h"
@@ -63,6 +64,7 @@ void CollectorService::RunForever() {
 
   std::unique_ptr<ContainerInfoInspector> container_info_inspector;
   std::unique_ptr<NetworkStatusInspector> network_status_inspector;
+  std::unique_ptr<CollectorConfigInspector> collector_config_inspector;
 
   CLOG(INFO) << "Network scrape interval set to " << config_.ScrapeInterval() << " seconds";
 
@@ -111,6 +113,8 @@ void CollectorService::RunForever() {
     server.addHandler(container_info_inspector->kBaseRoute, container_info_inspector.get());
     network_status_inspector = std::make_unique<NetworkStatusInspector>(conn_tracker);
     server.addHandler(network_status_inspector->kBaseRoute, network_status_inspector.get());
+    collector_config_inspector = std::make_unique<CollectorConfigInspector>(std::make_shared<CollectorConfig>(config_));
+    server.addHandler(collector_config_inspector->kBaseRoute, collector_config_inspector.get());
   }
 
   system_inspector_.Init(config_, conn_tracker);

docs/troubleshooting.md

@@ -602,3 +602,8 @@ $ curl "http://<collector>:8080/state/network/connection?container=c6f030bc4b42&
   ]
 }
 ```
+
+### Config endpoint
+The runtime configuration can be obtained using
+$ curl "http://<collector>:8080/state/config"
+