This is the new *Amazon CloudFormation Template Reference Guide*. Please update your bookmarks and links. For help getting started with CloudFormation, see the [Amazon CloudFormation User Guide](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/Welcome.html).

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

The Spot Instance replacement strategy to use when Amazon EC2 emits a rebalance notification signal that your Spot Instance is at an elevated risk of being interrupted. For more information, see [Capacity rebalancing](https://docs.amazonaws.cn/AWSEC2/latest/UserGuide/ec2-fleet-capacity-rebalance.html) in the *Amazon EC2 User Guide*.

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

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

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

```
{
  "[ReplacementStrategy](#cfn-ec2-ec2fleet-capacityrebalance-replacementstrategy)" : String,
  "[TerminationDelay](#cfn-ec2-ec2fleet-capacityrebalance-terminationdelay)" : Integer
}
```

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

```
  [ReplacementStrategy](#cfn-ec2-ec2fleet-capacityrebalance-replacementstrategy): String
  [TerminationDelay](#cfn-ec2-ec2fleet-capacityrebalance-terminationdelay): Integer
```

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

`ReplacementStrategy`  <a name="cfn-ec2-ec2fleet-capacityrebalance-replacementstrategy"></a>
The replacement strategy to use. Only available for fleets of type `maintain`.  
`launch` - EC2 Fleet launches a replacement Spot Instance when a rebalance notification is emitted for an existing Spot Instance in the fleet. EC2 Fleet does not terminate the instances that receive a rebalance notification. You can terminate the old instances, or you can leave them running. You are charged for all instances while they are running.   
`launch-before-terminate` - EC2 Fleet launches a replacement Spot Instance when a rebalance notification is emitted for an existing Spot Instance in the fleet, and then, after a delay that you specify (in `TerminationDelay`), terminates the instances that received a rebalance notification.  
*Required*: No  
*Type*: String  
*Allowed values*: `launch | launch-before-terminate`  
*Update requires*: [Replacement](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`TerminationDelay`  <a name="cfn-ec2-ec2fleet-capacityrebalance-terminationdelay"></a>
The amount of time (in seconds) that Amazon EC2 waits before terminating the old Spot Instance after launching a new replacement Spot Instance.  
Required when `ReplacementStrategy` is set to `launch-before-terminate`.  
Not valid when `ReplacementStrategy` is set to `launch`.  
Valid values: Minimum value of `120` seconds. Maximum value of `7200` seconds.  
*Required*: No  
*Type*: Integer  
*Update requires*: [Replacement](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)