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# AWS::EC2::EC2Fleet ReservedCapacityOptionsRequest
<a name="aws-properties-ec2-ec2fleet-reservedcapacityoptionsrequest"></a>

Defines EC2 Fleet preferences for utilizing reserved capacity when `DefaultTargetCapacityType` is set to `reserved-capacity`. EC2 Fleet can fulfill reserved capacity using On-Demand Capacity Reservations, Capacity Blocks for ML, and interruptible Capacity Reservations.

**Note**  
This configuration can only be used if the EC2 Fleet is of type `instant`.

When you specify `ReservedCapacityOptions`, you must also set `DefaultTargetCapacityType` to `reserved-capacity` in the `TargetCapacitySpecification`.

For more information about interruptible Capacity Reservations, see [Launch instances into an interruptible Capacity Reservation](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-fleet-launch-instances-interruptible-cr-walkthrough.html) in the *Amazon EC2 User Guide*.

## Syntax
<a name="aws-properties-ec2-ec2fleet-reservedcapacityoptionsrequest-syntax"></a>

To declare this entity in your CloudFormation template, use the following syntax:

### JSON
<a name="aws-properties-ec2-ec2fleet-reservedcapacityoptionsrequest-syntax.json"></a>

```
{
  "[AllocationStrategy](#cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-allocationstrategy)" : {{String}},
  "[CapacityReservationTarget](#cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-capacityreservationtarget)" : {{CapacityReservationTargetRequest}},
  "[ReservationTypes](#cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-reservationtypes)" : {{[ String, ... ]}},
  "[ReservedCapacityFallbackOptions](#cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-reservedcapacityfallbackoptions)" : {{ReservedCapacityFallbackOptionsRequest}}
}
```

### YAML
<a name="aws-properties-ec2-ec2fleet-reservedcapacityoptionsrequest-syntax.yaml"></a>

```
  [AllocationStrategy](#cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-allocationstrategy): {{String}}
  [CapacityReservationTarget](#cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-capacityreservationtarget): {{
    CapacityReservationTargetRequest}}
  [ReservationTypes](#cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-reservationtypes): {{
    - String}}
  [ReservedCapacityFallbackOptions](#cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-reservedcapacityfallbackoptions): {{
    ReservedCapacityFallbackOptionsRequest}}
```

## Properties
<a name="aws-properties-ec2-ec2fleet-reservedcapacityoptionsrequest-properties"></a>

`AllocationStrategy`  <a name="cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-allocationstrategy"></a>
The strategy that determines the order in which EC2 Fleet launches instances across the reservation types that you specify. The only supported value is `prioritized`, which launches instances in the priority order that you specify in your launch template overrides. If you don't specify an allocation strategy, instances are launched in a random order.  
*Required*: No  
*Type*: String  
*Allowed values*: `prioritized`  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`CapacityReservationTarget`  <a name="cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-capacityreservationtarget"></a>
The Capacity Reservations or Capacity Reservation Resource Groups to use for fulfilling the EC2 Fleet request. You can specify Capacity Reservation IDs or a Capacity Reservation Resource Group ARN, but not both.  
*Required*: No  
*Type*: [CapacityReservationTargetRequest](aws-properties-ec2-ec2fleet-capacityreservationtargetrequest.md)  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`ReservationTypes`  <a name="cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-reservationtypes"></a>
The types of Capacity Reservations to use for fulfilling the EC2 Fleet request. This is an ordered list: EC2 Fleet attempts to launch instances into each Capacity Reservation type in the order that you specify them before moving on to the next type.  
*Required*: No  
*Type*: Array of String  
*Allowed values*: `on-demand-capacity-reservation | capacity-block | interruptible-capacity-reservation`  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`ReservedCapacityFallbackOptions`  <a name="cfn-ec2-ec2fleet-reservedcapacityoptionsrequest-reservedcapacityfallbackoptions"></a>
The fallback behavior for the EC2 Fleet when there is not enough reserved capacity available to meet the target capacity. This member takes a `ReservedCapacityFallbackOptionsRequest` structure, in which you set `MarketTypes` to the instance purchasing options to fall back to.  
*Required*: No  
*Type*: [ReservedCapacityFallbackOptionsRequest](aws-properties-ec2-ec2fleet-reservedcapacityfallbackoptionsrequest.md)  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)