*`resource_id` - (Required) The resource type and unique identifier string for the resource associated with the scalable target. For Amazon ECS services, this value is the resource type, followed by the cluster name and service name, such as `service/default/sample-webapp`. For Amazon EC2 Spot fleet requests, the resource type is `spot-fleet-request`, and the identifier is the Spot fleet request ID; for example, `spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE`.
*`scalable_dimension` - (Required) The scalable dimension of the scalable target. The scalable dimension contains the service namespace, resource type, and scaling property, such as `ecs:service:DesiredCount` for the desired task count of an Amazon ECS service, or `ec2:spot-fleet-request:TargetCapacity` for the target capacity of an Amazon EC2 Spot fleet request.
*`service_namespace` - (Required) The AWS service namespace of the scalable target. Valid values are `ecs` for Amazon ECS services and `ec2` Amazon EC2 Spot fleet requests.