Set Lambda faas.invoked_region from the backfilled region in the response hook

Author: andreiborza

packages/server-utils/src/integrations/tracing-channel/aws-sdk/services/lambda.ts

@@ -25,9 +25,6 @@ export class LambdaServiceExtension implements ServiceExtension {
           [ATTR_FAAS_INVOKED_NAME]: functionName,
           [ATTR_FAAS_INVOKED_PROVIDER]: 'aws',
         };
-        if (request.region) {
-          spanAttributes[ATTR_FAAS_INVOKED_REGION] = request.region;
-        }
         spanName = `${functionName} ${INVOKE_COMMAND}`;
         break;
     }
@@ -47,6 +44,11 @@ export class LambdaServiceExtension implements ServiceExtension {
   public responseHook(response: NormalizedResponse, span: Span): void {
     if (response.request.commandName === INVOKE_COMMAND) {
       span.setAttribute(ATTR_FAAS_EXECUTION, response.requestId);
+      // Region resolves asynchronously after `requestPreSpanHook`, so it's backfilled onto the
+      // normalized request and read here (same timing as `cloud.region`).
+      if (response.request.region) {
+        span.setAttribute(ATTR_FAAS_INVOKED_REGION, response.request.region);
+      }
     }
   }
 }