Provides an ECS service - effectively a task that is expected to run until an error occures or user terminates it (typically a webserver or a database).
See [ECS Services section in AWS developer guide](http://docs.aws.amazon.com/AmazonECS/latest/developerguide/ecs_services.html).
*`name` - (Required) The name of the service (up to 255 letters, numbers, hyphens, and underscores)
*`task_definition` - (Required) The family and revision (`family:revision`) or full ARN of the task definition that you want to run in your service.
*`desired_count` - (Required) The number of instances of the task definition to place and keep running
*`cluster` - (Optional) ARN of an ECS cluster
*`iam_role` - (Optional) IAM role that allows your Amazon ECS container agent to make calls to your load balancer on your behalf. This parameter is only required if you are using a load balancer with your service.