How to receive public ipv4 from AWS ECS via Terraform

Hello everyone! I want to share with you my Terraform solution which allows to receive public IP address from Elastic Container Service Tasks.

You have simple service like that:

resource "aws_ecs_service" "test" {
  name            = "test"
  cluster         = data.aws_ecs_cluster.test.id
  task_definition = aws_ecs_task_definition.test.id
  launch_type = "FARGATE"
  desired_count   = 1
  network_configuration {
    subnets = ["test"]
    security_groups  = ["test"]
    assign_public_ip = true
  }
}        

Let`s add "enable_ecs_managed_tags = true" , it allows you to see services what connected with Elastic Network Interface (ENI IP), we enabled it by "assign_public_ip = true" line

resource "aws_ecs_service" "test" {
  name            = "test"
  cluster         = data.aws_ecs_cluster.test.id
  task_definition = aws_ecs_task_definition.test.id
  launch_type = "FARGATE"
  desired_count   = 1
  enable_ecs_managed_tags = true
  network_configuration {
    subnets = ["test"]
    security_groups  = ["test"]
    assign_public_ip = true
  }
}        

Now we can find the ENI with "aws:ecs:serviceName" tag using this data source:

data "aws_network_interfaces" "test" {
  tags = {
    "aws:ecs:serviceName" = aws_ecs_service.test.name
  }
}        

We receive the ID with this data source , next step to find our public Ipv4 from this interface:

data "aws_network_interface" "eni-ip" {
  depends_on = [ aws_ecs_service.test ]
  id = data.aws_network_interfaces.test.ids[0]
}        

It`s done. You can receive your IP and get via output:

output "eni_ip" {
  value = data.aws_network_interface.eni-ip.association[0].public_ip
}        

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