Cloudformation: Reference created ACM Certificate in other region - aws-cloudformation

Question

Since https certificates for Cloudfront can only be created in us-east-1 and my entire stack is created in eu-west-1 I wanted to create a stack in us-east-1 that contains the ACM certificate, and then use that certificate in my stack(s) in eu-west-1.
The only problem is, how do I reference this certificate without hardcoding it, as I can't ImportValue an output in another region.
e.g.
Distribution:
Type: AWS::CloudFront::Distribution
Properties:
DistributionConfig:
Origins:
- DomainName: !GetAtt S3Bucket.RegionalDomainName
Id: ****
CustomOriginConfig:
HTTPPort: '80'
HTTPSPort: '443'
OriginProtocolPolicy: https-only
DefaultRootObject: 'index.html'
Enabled: true
Aliases:
- 'bla.bla.com'
DefaultCacheBehavior:
TargetOriginId: '*-origin'
AllowedMethods:
- GET
- HEAD
ViewerProtocolPolicy: redirect-to-https
CachePolicyId: '658327ea-f89d-4fab-a63d-7e88639e58f6'
ViewerCertificate:
AcmCertificateArn: !ImportValue ****
SslSupportMethod: sni-only
What do I need to put on the AcmCertificateArn line when I deploy this in eu-west-1?

Answer 1

As you've pointed out, you can't make cross-region export/import references between stacks in different regions. In this case, usually you would provide the Certificate ARN as an input parameter to your stack in eu-west-1.
The other options would involve the use of SSM parameters dynamic references to pass the value of the certificate's ARN. For fully automated solution, you would need to develop a custom resource in eu-west-1 in the form of a lambda function. The function would query the stack in us-east-1 for the arn in its outputs and return the arn to the stack in eu-west-1.