How to use !Ref or Fn:GetAtt in lift models

[cmcnicholas]

Hi, I have opened a PR with support for queue subscriptions here: #344

But does anyone know how to use !Ref declarations with the lift models and/or CDK? I can't find any examples in this repo but essentially I would like to alter the code so it doesn't require an ARN but can depend on another serverless resource, e.g.

resources:
  Resources:
    MyTopic:
      Type: 'AWS::SNS::Topic'
      Properties:
        TopicName: SuperTopic

constructs:
  my-queue:
    type: queue
    worker:
      handler: worker.handler
    subscriptions:
      - topic: !Ref MyTopic # this doesn't work

is there examples out there of how this is achieved either within lift or separate plugins?

[cmcnicholas]

OK further to the above I have managed to get the following to work:

const fn = Fn.getAtt("MyTopic", "TopicArn");
const topic = Topic.fromTopicArn(this, "SomeId", fn.toString());
topic.addSubscription(new SqsSubscription(this.queue, { filterPolicy, rawMessageDelivery: true }));

if there a friendly way to serialise/deserialise Fn.getAtt("MyTopic", "TopicArn") into yaml? Examples show use of:

constructs:
  one-of-them-queues:
    type: queue
    worker:
      handler: worker.handler
    subscriptions:
      - topicRef:
          Fn::GetAtt:
            - MyTopic
            - TopicArn

for example, but what type am I expecting topicRef to be and/or how do I deserialise to an Fn so I can provide a serialised arn to fromTopicArn ?

[cmcnicholas]

Managed to resolve this, see solution in #344