API Gateway: Not defaulting to Lambda_Proxy integration type

[mstig]

Bug Report

API Gateway no longer deploys with the default integration request set to Lambda_Proxy.

Description

Documentation states that the default Integration Request type is Lambda_Proxy, however this is not happening with recent versions of Serverless. No integration type is declared in the serverless yml file, however the default behavior is different depending on the Serverless version used.

With Serverless 1.32, the api deploys properly and uses the defaults per documentation, with 1.44 (intermediate versions have not been tested, first noticed this issue working/not working with 1.32 and 1.44) and higher.

Adding " integration: lambda_proxy " to the serverless.yml file causes the api gateway to set the type to Lambda_Proxy, but still retains the "Headers: X-Amz-Invocation-Type" setting that is being attached from the newer versions, and the API does not work.

1. What did you do?
   Deployed Lambda Functions with http events tied to API Gateway

2. What happened?

The Integration Request was not properly applied, and does not use the Lambda_Proxy setting that is listed as the default within the serverless documentation.

Adding "integration: lambda_proxy" adjusts the type setting, but retains a header that still causes errors when using the api.

1. What should've happened?

The integration type should've been set to LAMBDA_PROXY with no headers.

1. What's the content of your serverless.yml file?
   functions:
   fnName:
   handler: api/handler.function
   memorySize: 256
   events:
   • http:
     path: invoice/upload/v2.0
     method: post
     async: true
     authorizer:
     arn: ${self:custom.authorizeFunction.${self:provider.stage}}
     resultTtlInSeconds: 0
     type: request
     integration: lambda_proxy # This was only added after the fact, does not fix the issue
     cors:
     origin: ${self:custom.corsOrigin.${self:provider.stage}}
     headers:
     - Content-Type
     - X-Amz-Date
     - Authorization
     - authorization
     - X-Api-Key
     - X-Amz-Security-Token
     - X-Amz-User-Agent
     - cache-control
     allowCredentials: false