determine aws event version when version not specified.

Author: xinghengwang

lib/index.js

@@ -304,7 +304,7 @@ function constructBaseLogData(
       event.requestContext.http.method;
   }
 
-  logData.request.apiVerion = options.getApiVersion(event, context);
+  logData.request.apiVersion = options.getApiVersion(event, context);
 
   if (isV1) {
     logData.request.ipAddress =
@@ -364,6 +364,20 @@ function constructBaseLogData(
   return logData;
 }
 
+function determineIsEventVersionV1(event) {
+  if (event.version === '1.0') {
+    return true;
+  }
+  // per aws event spec https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-develop-integrations-lambda.html
+  // events suppose to have version specified.
+  // For some reason, the version is not specified in some cases.
+  // so we use heuristic below.
+  if (event.httpMethod) {
+    return true;
+  }
+
+  return false;
+}
 
 function logEvent(event, context, err, result, options, moesifController) {
   // v1 has httpMethod, v2 has requestContext
@@ -382,7 +396,7 @@ function logEvent(event, context, err, result, options, moesifController) {
     return Promise.resolve();
   }
 
-  const isV1 = event.version === '1.0';
+  const isV1 = determineIsEventVersionV1(event);
 
   var logData = constructBaseLogData(
     event,