How to Pass Multiple URLs to AllowOrigins in CloudFormation Template - amazon-web-services

Question

I am using a CloudFormation template in YML format.
Depending on the environment, I need to be able to use different URLs for the Allowed Origins attribute of my CorsConfiguration. Ideally, I would like to use a Parameter defined like this:
AllowedOrigins:
Description: Allowed Origins
Type: String
AllowedPattern: '.+'
I have tried to pass in a delimited string (i.e. "http://localhost:4200,http://localhost:4201"), and split the values like this:
OnboardingHttpApi:
Type: AWS::Serverless::HttpApi
Properties:
CorsConfiguration:
AllowOrigins: !Split [ ",", !Ref AllowedOrigins ]
The response in CloudFormation is:
Warnings found during import: CORS Scheme is malformed, ignoring. (Service: AmazonApiGatewayV2; Status Code: 400; Error Code: BadRequestException; Request ID: 21072c02-70c3-473d-9629-784005226bd4; Proxy: null) (Service: null; Status Code: 404; Error Code: BadRequestException; Request ID: null; Proxy: null)

Answer 1

This is the answer I got from AWS Support:
The Split function is for splitting strings into a list, but it is not for referencing an attribute. It is designed to be used with the Select function or other functions. So it is not a stand-alone function to be used for referencing. For this, you can use the CommaDelimitedList parameter type. You can use the CommaDelimitedList parameter type to specify multiple string values in a single parameter. Once you pass the CommaDelimitedList parameter value, you can reference it later on your template. Here is a CloudFormation template that works:
AWSTemplateFormatVersion: 2010-09-09
Transform: 'AWS::Serverless-2016-10-31'
Parameters:
AllowedOriginsURLs:
Type: CommaDelimitedList
Default: 'https://example.com,https://example2.com'
Description: Please enter your URLs
Resources:
HttpApi:
Type: 'AWS::Serverless::HttpApi'
Properties:
StageName: my-stage-name
Tags:
Tag: MyTag
StageVariables:
StageVar: Value
CorsConfiguration:
AllowOrigins: !Ref AllowedOriginsURLs
AllowHeaders: [ x-apigateway-header ]
AllowMethods: [ GET ]
MaxAge: 600
AllowCredentials: true
The AllowedOriginsURLs parameter is of type CommaDelimitedList, with the default being 'http://localhost:4200,http://localhost:4201'. You can change this parameter on startup, then you can reference AllowedOriginsURLs on AllowOrigins.