serverless: custom response parameter mappings in HttpApi

Question

I am trying to send a custom Response header from my API, I tried using events.response.statusCodes but it is not working, looks like it was only implemented for http but not for httpApi event.

functions:
  myfunction:
    name: test
    handler: src/index.handler
    events:
      - httpApi:
          path: /graphql
          method: post
          response:
            statusCodes:
              200:
                headers:
                  Strict-Transport-Security: "'max-age=31536000'"
              500:
                headers:
                  Strict-Transport-Security: "'max-age=31536000'"

Answer 1

You are corrrect that it hasn't been implemented for httpApi. It is supported by HTTP API on AWS level though, so you can override manually properties of created AWS::ApiGatewayV2::Integration by using the following syntax:

resources:
  extensions:
    HttpApiIntegrationMain:
      Properties:
        ResponseParameters:
          200:
            ResponseParameters:
              - Source: "'max-age=31536000'"
                Destination: overwrite:header.Strict-Transport-Security
          500:
            ResponseParameters:
              - Source: "'max-age=31536000'"
                Destination: overwrite:header.Strict-Transport-Security

See CloudFormation docs for that resource for reference: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-apigatewayv2-integration.html#cfn-apigatewayv2-integration-responseparameters