ping-pong-stack-sns-alarms.yml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Cross Region SNS-Lambda Subscription

Parameters:
  OtherRegion:
    Type: String

Resources:
  # The AWS Console will not show this trigger, but it works
  SNSSubScription:
    Type: AWS::SNS::Subscription
    Properties:
      Endpoint: !Sub arn:aws:lambda:${OtherRegion}:${AWS::AccountId}:function:apigw-multiregion-lambda-backend-swap
      Protocol: lambda
      TopicArn: !ImportValue apigw-multiregion-lambda-backend:AlarmSNSArn

  # Just need to allow any SNS to invoke it
  LambdaInvokePermission:
    Type: "AWS::Lambda::Permission"
    Properties:
      FunctionName: !ImportValue apigw-multiregion-lambda-backend:KickerFunctionArn
      Action: "lambda:InvokeFunction"
      Principal: "sns.amazonaws.com"