fix(otel-nestjs-instrumentation): force RPC span kind when interceptor starts fallback transaction

libs/otel-nestjs-instrumentation/src/internal/otel-instrumentation.ts

@@ -31,9 +31,15 @@
 	 *
 	 * @param transactionName - The name for the span
 	 * @param context - The NestJS execution context
-	 * @returns Object containing trace ID, span ID, and optional finalizer function
+	 * @param effectiveType When provided, overrides automatic type detection
+	 *   (e.g., 'rpc' from interceptor fallback)
+	 * @returns Trace ID or undefined if tracer is unavailable
 	 */
-	create(transactionName: string, context: ExecutionContext) {
+	create(
+		transactionName: string,
+		context: ExecutionContext,
+		effectiveType?: 'http' | 'rpc',
+	) {
 		// Create a new span since none exists
 		const tracer = otel.trace.getTracer(tracerName);
 		if (!tracer) return undefined;
@@ -54,11 +60,13 @@
 			// Use default context if extraction fails
 		}
 
-		// Determine span kind and attributes based on context type
+		// Determine span kind and attributes based on effective type
 		let spanKind = otel.SpanKind.INTERNAL; // default for unknown contexts
 		const attributes: Record<string, string> = {};
 
-		if (context.getType() === 'http') {
+		effectiveType ??= context.getType() as 'http' | 'rpc';
+
+		if (effectiveType === 'http') {
 			spanKind = otel.SpanKind.SERVER;
 			try {
 				const request = context.switchToHttp().getRequest<{
@@ -74,10 +82,10 @@
 			} catch {
 				// Ignore request extraction errors
 			}
-		} else if (context.getType() === 'rpc') {
+		} else if (effectiveType === 'rpc') {
 			spanKind = otel.SpanKind.SERVER;
 			try {
-				attributes['rpc.method'] = context.getHandler()?.name || 'Call';
+				attributes['rpc.method'] = context.getHandler()?.name ?? 'Call';
 			} catch {
 				// Ignore RPC context extraction errors
 			}

libs/otel-nestjs-instrumentation/src/otel.interceptor.ts

@@ -106,7 +106,14 @@ export class OtelInterceptor implements NestInterceptor {
 	 * @returns Observable that completes when the request is finished
 	 */
 	intercept(context: ExecutionContext, next: CallHandler) {
-		startOtelInstrumentationIfAbsent(context, this.context, this.emitter);
+		// If no guard ran (e.g. gRPC/microservice), force RPC since HTTP spans
+		// would have been started by the guard already.
+		startOtelInstrumentationIfAbsent(
+			context,
+			this.context,
+			this.emitter,
+			'rpc',
+		);
 		const span = otel.trace.getActiveSpan();
 		if (!span) return next.handle();
 		const traceId = span.spanContext().traceId;

libs/otel-nestjs-instrumentation/src/start-otel-instrumentation-if-absent.ts

@@ -11,11 +11,14 @@ import {
  * @param context ExecutionContext to use
  * @param internalContext The async local storage context
  * @param emitter Event emitter for monitoring
+ * @param effectiveType When provided, overrides automatic type detection
+ *   (e.g., 'rpc' when called from interceptor as fallback for non-HTTP transports)
  */
 export function startOtelInstrumentationIfAbsent(
 	context: ExecutionContext,
 	internalContext: InternalContext,
 	emitter: EventEmitter,
+	effectiveType?: 'http' | 'rpc',
 ): void {
 	// If a span is already active, don't create another one
 	const existingTraceId = otelInstrumentation.getCurrentTransactionId();
@@ -25,7 +28,11 @@ export function startOtelInstrumentationIfAbsent(
 	const transactionName = getTransactionName(context);
 
 	try {
-		traceId = otelInstrumentation.create(transactionName, context);
+		traceId = otelInstrumentation.create(
+			transactionName,
+			context,
+			effectiveType,
+		);
 	} catch (error) {
 		emitter.emit('spanStartFailed', error);
 		return;

libs/otel-nestjs-instrumentation/test/internal/otel-instrumentation.spec.ts

@@ -258,7 +258,7 @@ describe('OtelInstrumentation', () => {
 				{
 					kind: mockOtelApi.SpanKind.SERVER,
 					attributes: {
-						'rpc.method': 'Call', // Fallback when no name
+						'rpc.method': '', // Empty string preserved by ?? (not null/undefined)
 						'nestjs.controller': 'RpcController',
 						'nestjs.handler': 'unknown', // Falls back to 'unknown' when name is empty
 					},

libs/otel-nestjs-instrumentation/test/otel-context-guard.spec.ts

@@ -100,6 +100,7 @@ describe('OtelContextGuard', () => {
 			expect(mockOtelInstrumentation.create).toHaveBeenCalledWith(
 				expect.any(String),
 				mockExecutionContext,
+				undefined,
 			);
 		});
 
@@ -182,6 +183,7 @@ describe('OtelContextGuard', () => {
 			expect(mockOtelInstrumentation.create).toHaveBeenCalledWith(
 				expect.stringContaining('TestController.testMethod'),
 				mockContext,
+				undefined,
 			);
 		});
 
@@ -200,6 +202,7 @@ describe('OtelContextGuard', () => {
 			expect(mockOtelInstrumentation.create).toHaveBeenCalledWith(
 				expect.stringContaining('TestController.processMessage'),
 				mockContext,
+				undefined,
 			);
 		});
 
@@ -216,6 +219,7 @@ describe('OtelContextGuard', () => {
 			expect(mockOtelInstrumentation.create).toHaveBeenCalledWith(
 				expect.stringContaining('TestController.testMethod'),
 				mockContext,
+				undefined,
 			);
 		});
 

libs/otel-nestjs-instrumentation/test/otel-interceptor.spec.ts

@@ -458,6 +458,7 @@ describe('OtelInterceptor', () => {
 			expect(mockOtelInstrumentation.create).toHaveBeenCalledWith(
 				expect.stringContaining('TestController'),
 				mockExecutionContext,
+				'rpc', // interceptor fallback forces RPC type
 			);
 			expect(mockEmitter.emit).toHaveBeenCalledWith(
 				'spanStarted',