Use current ACTIVE task in ECS service definition

service.tf

# Get the current ACTIVE revision in ECS task family
data "aws_ecs_task_definition" "web" {
  task_definition = "${module.web.ecs_task_family}"
}
 
resource "aws_ecs_service" "web" {
  # Use the latest task revision - either the existing one, or the newly created
  # if the task was updated.
  task_definition = "${max("${aws_ecs_task_definition.web.revision}", "${var.ecs_task_current_revision}")}"
}