AWS ECS Fargate dynamically register IP to target group

Question

I use AWS at work and I am fairly new to this.

I have multiple Services with one Task/Container running. Each Container is fundamentally the same with a few changes, it's basically for different stages/deployments. I have one target group for each, so my load balancer routes requests from specific domains to each.

For example: if host is example1.com then forward to exampleTargetGroup1 and so on.

The Problem

As you may know each time a container is updated, its IP changes, hence I have to re-register the new IP to the target group

I have found several approaches to this problem. Most of them suggest to use a Network Load Balancer for a static IP, but this doesn't work because, as I understand it, it registers the containers automatically on updates.

Another solution is to trigger a Lambda function on a cloud watch events when the Task is being updated. The function grabs the IP and updates the Route53 record. My Idea was to take this approach and deregister the old IP in the target group and register the new one.

My Questions

Is there a better solution to this or did I understand the first solutions wrong? If the last solution is optimal for my problem is there maybe a code sample so I won't need to figure it out?

EDIT:

Thanks to Mark B I now know, you should preferably use the AWS API or a tool like Terraform to create an ECS Service and associating a target group to it.