AWS ECS Fargate dynamically register IP to target group - amazon-web-services

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.

Answer 1

"but this doesn't work because, as I understand it, it registers the
containers automatically on updates."
I think you are misunderstanding something here. Each ECS service should be associated with a load balancer Target Group. Whenever the service creates a task, the service will automatically add that task's IP to the target group. Whenever the service removes a task, it will also remove that task's IP from the target group. This works with both Network Load Balancers and Application Load Balancers.
You stated the following:
"I have multiple Services with one Task/Container running"
So you have one task per service, and one service per target group. From your description, your architecture should look like this:
One load Balancer with multiple domains pointing at it.
In the Load Balancer listener configuration, you have each domain configured to route to a different target group.
Each ECS service configured with a task count of 1
Load balancer -> domain name 1 -> target group 1 -> ECS service 1 -> ECS task 1
Load balancer -> domain name 2 -> target group 2 -> ECS service 2 -> ECS task 2
Load balancer -> domain name 3 -> target group 3 -> ECS service 3 -> ECS task 3
etc...
In the above scenario, as long as you have each ECS service configured with the appropriate target group, each time that service redeploys a task it will automatically update the target group to point to the updated task.
In other words ECS will "dynamically register the IP to target group", exactly like you are wanting.