I am currently using an ECS Fargate service which has two ECS tasks, one of which is an API, and another of which is an authentication proxy I wrote. I am looking to ditch this custom code and replace it with a Cognito action. However, I see that I need to specify a user pool domain. I already have an existing front end which lets a user from the user pool enter their email and in turn, receive an email OTP. I am currently testing this in a sandbox environment from PluralSight and I need to recreate it every 4 hours (i.e. using a different AWS account), so I am not sure what to do about the user pool domain. Right now, the code just points at the ALB URL to make requests. AFAICT, I can't use that as the domain, although my research has left me confused. Am I correct about that? If I don't use a custom domain, it's my understanding that I would be forced to use AWS's sign-in page. Is that accurate?…