# CapacityReservationSpecification


Describes an instance's Capacity Reservation targeting option. 

Use the `CapacityReservationPreference` parameter to configure the instance to run as an On-Demand Instance, to run in any `open` Capacity Reservation that has matching attributes, or to run only in a Capacity Reservation or Capacity Reservation group. Use the `CapacityReservationTarget` parameter to explicitly target a specific Capacity Reservation or a Capacity Reservation group.

You can only specify `CapacityReservationPreference` and `CapacityReservationTarget` if the `CapacityReservationPreference` is `capacity-reservations-only`.

## Contents


 ** CapacityReservationPreference **   
Indicates the instance's Capacity Reservation preferences. Possible preferences include:  
+  `capacity-reservations-only` - The instance will only run in a Capacity Reservation or Capacity Reservation group. If capacity isn't available, the instance will fail to launch.
+  `open` - The instance can run in any `open` Capacity Reservation that has matching attributes (instance type, platform, Availability Zone, and tenancy). If capacity isn't available, the instance runs as an On-Demand Instance.
+  `none` - The instance doesn't run in a Capacity Reservation even if one is available. The instance runs as an On-Demand Instance.
Type: String  
Valid Values: `capacity-reservations-only | open | none`   
Required: No

 ** CapacityReservationTarget **   
Information about the target Capacity Reservation or Capacity Reservation 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/ec2-2016-11-15/CapacityReservationSpecification) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/ec2-2016-11-15/CapacityReservationSpecification) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/ec2-2016-11-15/CapacityReservationSpecification)