# CapacityReservationSpecification


 Describes the Capacity Reservation preference and targeting options. If you specify `open` or `none` for `CapacityReservationPreference`, do not specify a `CapacityReservationTarget`. 

## Contents


 ** CapacityReservationPreference **   
 The capacity reservation preference. The following options are available:   
+  `capacity-reservations-only` - Auto Scaling will only launch instances into a Capacity Reservation or Capacity Reservation resource group. If capacity isn't available, instances will fail to launch.
+  `capacity-reservations-first` - Auto Scaling will try to launch instances into a Capacity Reservation or Capacity Reservation resource group first. If capacity isn't available, instances will run in On-Demand capacity.
+  `none` - Auto Scaling will not launch instances into a Capacity Reservation. Instances will run in On-Demand capacity. 
+  `default` - Auto Scaling uses the Capacity Reservation preference from your launch template or an open Capacity Reservation.
Type: String  
Valid Values: `capacity-reservations-only | capacity-reservations-first | none | default`   
Required: No

 ** CapacityReservationTarget **   
 Describes a target Capacity Reservation or Capacity Reservation resource group.   
Type: [CapacityReservationTarget](API_CapacityReservationTarget.md) object  
Required: No

## See Also


For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/autoscaling-2011-01-01/CapacityReservationSpecification) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/autoscaling-2011-01-01/CapacityReservationSpecification) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/autoscaling-2011-01-01/CapacityReservationSpecification)