Unable to execute Lambda in Async mode via API Gateway POST request - amazon-web-services

Question

Why currently there no way to execute AWS Lambda in asynchronous mode via Gateway API without involving intermediary Lambda just for calling invoke() method?
Even if i add integration like this:
r = client.put_integration(
restApiId=rest_api_id,
resourceId=resource_id,
httpMethod='POST',
type='AWS',
integrationHttpMethod='POST',
uri=uri,
requestParameters={
'integration.request.header.X-Amz-Invocation-Type': "'Event'",
'integration.request.header.Invocation-Type': "'Event'"
}
)
It still executed synchronously...
Are there some platform limitation or so?

Answer 1

I have an example Swagger document which you can switch invocation type to Lambda function. I guess you already got how to map the header to trigger the different invocation types, but I think you might forget to deploy the API.
Swagger
{
"swagger": "2.0",
"info": {
"version": "2016-02-11T22:00:31Z",
"title": "LambdaAsync"
},
"host": "<placeholder>",
"basePath": "<placeholder>",
"schemes": [
"https"
],
"paths": {
"/": {
"get": {
"produces": [
"application/json"
],
"parameters": [
{
"name": "X-Amz-Invocation-Type",
"in": "header",
"required": false,
"type": "string"
}
],
"responses": {
"200": {
"description": "200 response",
"schema": {
"$ref": "#/definitions/Empty"
}
}
},
"x-amazon-apigateway-integration": {
"passthroughBehavior": "when_no_match",
"httpMethod": "POST",
"uri": "arn:aws:apigateway:us-east-1:lambda:path/2015-03-31/functions/arn:aws:lambda:us-east-1:<account>:function:<function_name>/invocations?Qualifier=$LATEST",
"responses": {
"default": {
"statusCode": "200"
}
},
"requestParameters": {
"integration.request.header.X-Amz-Invocation-Type": "method.request.header.X-Amz-Invocation-Type"
},
"type": "aws"
}
}
}
},
"definitions": {
"Empty": {
"type": "object",
"title": "Empty Schema"
}
}
}