Feature to add Nginx variables related to tracing context (#416)

* truezz

* try2

* working

* oka

* dfs

* Nginx tracing context variables added

* changes

* chamgess

* merge with main

* before merge

* Feature to include tracing info as nginx variables

* Improved code quality, added Readme

* Improved code quality2

* code quality improvement 3

Author: aryanishan1001

instrumentation/otel-webserver-module/README.md

@@ -182,8 +182,9 @@ Currently, Nginx Webserver module monitores some fixed set of modules, which get
 |*NginxModulePropagatorType*                   | w3c                 | OPTIONAL: Specify the Propagator used by the instrumentation (W3C and B3 propagators available). e.g.```NginxModulePropagatorType                  b3;```|
 |*NginxModuleOperationName*                   |                 | OPTIONAL: Specify the operation name (span name) for any specific endpoint.  e.g.```NginxModuleOperationName                  My_Backend;```|
 
+#### Other Configurations
 
-
+- Nginx variables related to traceing info - $opentelemetry_trace_id , $opentelemetry_span_id $opentelemetry_context_traceparent , $opentelemetry_context_b3
 
 ### Build and Installation
 #### Prerequisites

instrumentation/otel-webserver-module/include/core/sdkwrapper/ISdkWrapper.h

@@ -38,6 +38,8 @@ class ISdkWrapper {
 		const SpanKind& kind,
 		const OtelKeyValueMap& attributes,
 		const std::unordered_map<std::string, std::string>& carrier = {}) = 0;
+	
+	virtual std::string ReturnCurrentSpanId() = 0;
 
 	virtual void PopulatePropagationHeaders(
 		std::unordered_map<std::string, std::string>& carrier) = 0;

instrumentation/otel-webserver-module/include/core/sdkwrapper/SdkWrapper.h

@@ -41,6 +41,8 @@ class SdkWrapper : public ISdkWrapper{
 	void PopulatePropagationHeaders(
 		std::unordered_map<std::string, std::string>& carrier) override;
 
+	std::string ReturnCurrentSpanId() override;
+
 private:
 	trace::SpanKind GetTraceSpanKind(const SpanKind& kind);
 

instrumentation/otel-webserver-module/src/core/api/RequestProcessingEngine.cpp

@@ -86,7 +86,7 @@ OTEL_SDK_STATUS_CODE RequestProcessingEngine::startRequest(
     }
 
     auto span = m_sdkWrapper->CreateSpan(spanName, sdkwrapper::SpanKind::SERVER, keyValueMap, payload->get_http_headers());
-
+    
     LOG4CXX_TRACE(mLogger, "Span started for context: [" << wscontext
         <<"] SpanName: " << spanName << ", RequestProtocol: " << payload->get_request_protocol()
         <<" SpanId: " << span.get());
@@ -200,10 +200,12 @@ OTEL_SDK_STATUS_CODE RequestProcessingEngine::startInteraction(
     // TODO : confirm and update name later
     std::string spanName = payload->moduleName + "_" + payload->phaseName;
     keyValueMap["interactionType"] = "EXIT_CALL";
+    std::string parentSpanId = m_sdkWrapper->ReturnCurrentSpanId();
     auto interactionSpan = m_sdkWrapper->CreateSpan(spanName, SpanKind::CLIENT, keyValueMap);
     LOG4CXX_TRACE(mLogger, "Client Span started with SpanName: " << spanName
         << " Span Id: " << interactionSpan.get());
     m_sdkWrapper->PopulatePropagationHeaders(propagationHeaders);
+    propagationHeaders["Parent_Span_Id"] = parentSpanId;
 
     // Add the interaction to the request context.
     requestContext->addInteraction(interactionSpan);

instrumentation/otel-webserver-module/src/core/api/opentelemetry_ngx_api.cpp

@@ -179,7 +179,7 @@ OTEL_SDK_STATUS_CODE startModuleInteraction(OTEL_SDK_HANDLE_REQ req_handle_key,
                 propagationHeaders[*ix].name = temp_key;
                 char *temp_value= (char*)malloc(itr->second.size() + 1); 
                 std::strcpy(temp_value, itr->second.c_str());
-                 propagationHeaders[*ix].value = temp_value;
+                propagationHeaders[*ix].value = temp_value;
                 ++(*ix);
             }
         }

instrumentation/otel-webserver-module/src/core/sdkwrapper/ScopedSpan.cpp

@@ -30,7 +30,9 @@ ScopedSpan::ScopedSpan(
 {
 	trace::StartSpanOptions options{};
 	options.kind = kind;
+
 	mSpan = sdkHelperFactory->GetTracer()->StartSpan(name, attributes, options);
+
 	mScope.reset(new trace::Scope(mSpan));
 	mSpanKind = kind;
 }

instrumentation/otel-webserver-module/src/core/sdkwrapper/SdkWrapper.cpp

@@ -66,26 +66,37 @@ std::shared_ptr<IScopedSpan> SdkWrapper::CreateSpan(
 			mLogger));
 	}
 }
-
+std::string SdkWrapper::ReturnCurrentSpanId(){
+	
+	auto context = context::RuntimeContext::GetCurrent();
+	auto currentSpan = trace::GetSpan(context);
+	trace::SpanContext spanContext = currentSpan->GetContext();
+	trace::SpanId spanId = spanContext.span_id();
+	constexpr int len = 2 * trace::SpanId::kSize;
+	char* data = new char[len];
+	spanId.ToLowerBase16(nostd::span<char, len>{data, len});
+	std::string currentSpanId(data, len);
+	delete[] data;
+	return currentSpanId;
+}
 void SdkWrapper::PopulatePropagationHeaders(
 	std::unordered_map<std::string, std::string>& carrier) {
 
   // TODO : This is inefficient change as we are copying otel carrier data
   // into unordered map and sending it back to agent.
   // Ideally agent should keep otelCarrier data structure on its side.
-  auto otelCarrier = OtelCarrier();
+  	auto otelCarrier = OtelCarrier();
 	auto context = context::RuntimeContext::GetCurrent();
 	for (auto &propagators : mSdkHelperFactory->GetPropagators()) {
 		propagators->Inject(otelCarrier, context);
 	}
-
-  // copy all relevant kv pairs into carrier
-  for (int i = 0; i < CARRIER_HEADER_LEN; i++) {
-	auto carrier_header = otelCarrier.Get(CARRIER_HEADER_NAME[i]).data();
-	if(carrier_header != ""){
-	  	carrier[CARRIER_HEADER_NAME[i]] = otelCarrier.Get(CARRIER_HEADER_NAME[i]).data();
+	// copy all relevant kv pairs into carrier
+	for (int i = 0; i < CARRIER_HEADER_LEN; i++) {
+		auto carrier_header = otelCarrier.Get(CARRIER_HEADER_NAME[i]).data();
+		if(carrier_header != ""){
+			carrier[CARRIER_HEADER_NAME[i]] = otelCarrier.Get(CARRIER_HEADER_NAME[i]).data();
+		}
 	}
-  }
 }
 
 trace::SpanKind SdkWrapper::GetTraceSpanKind(const SpanKind& kind)