handle defaulting response for v2

Author: xinghengwang

lib/index.js

@@ -238,6 +238,33 @@ function mapResponseHeaders(event, context, result) {
   return headers;
 }
 
+// in V2
+// https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-develop-integrations-lambda.html
+// if there is no statusCode but valid JSON, API gateway will interpret
+// the response.
+function translateLambdaResultIfNeeded(result, isV1) {
+  if (isV1) {
+    return result || {};
+  }
+
+  if (result && result.statusCode) {
+    return result;
+  }
+
+  if (!result.statusCode && (typeof result === 'object' || typeof result === 'string')) {
+    return {
+      "isBase64Encoded": false,
+      "statusCode": 200,
+      "body": JSON.stringify(result),
+      "headers": {
+        "content-type": "application/json"
+      }
+    }
+  }
+
+  return result || {};
+}
+
 function constructBaseLogData(
   event,
   context,
@@ -292,7 +319,7 @@ function constructBaseLogData(
       event.requestContext.http.sourceIp;
   }
 
-  logData.request.headers = event.headers || {};
+  logData.request.headers = Object.assign({}, event.headers || {});
   logData.metadata = options.getMetadata(event, context);
 
   if (options.logBody && event.body) {
@@ -312,7 +339,8 @@ function constructBaseLogData(
     "created request: \n" + JSON.stringify(logData.request)
   );
 
-  var safeRes = result || {};
+  var safeRes = translateLambdaResultIfNeeded(result, isV1);
+
   logData.response.time = Math.max(
     new Date(logData.request.time).getTime(),
     Date.now()