I have a cloudformation template that creates an S3 bucket as part of a cloudformation stack. On the new version of my template, I 'm planning to migrate my application from S3 to EFS.
Is there a way to remove the S3 bucket resource from the template, without having it deleted? Ideally, I would like my older users to have the s3 bucket available after they upgrade, but for the new users to not have it at all. It looks like DeletionPolicies could help here, but the documentation on it says that it only applies to stack deletion, but not upgrades.
When you remove a resource from your template, and update a stack from this template, the resources will be deleted. There is no way to avoid that.
Since your existing users will continue using the S3 bucket, I would recommend preserving the bucket in your template. Remove it when the bucket has been removed from your product completely.
If needed, you could version your template (old vs. new).
If you absolutely need to remove the bucket from your template, you may be able to use a loophole. When CloudFormation deletes a bucket, the bucket must be empty. If it's not empty, then the bucket should be preserved and removed from your stack. You could experiment and see if it works for you. If it works in testing, then you can try using it in production.