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::AutoScaling::AutoScalingGroup MixedInstancesPolicy
<a name="aws-properties-autoscaling-autoscalinggroup-mixedinstancespolicy"></a>

Use this structure to launch multiple instance types and On-Demand Instances and Spot Instances within a single Auto Scaling group.

A mixed instances policy contains information that Amazon EC2 Auto Scaling can use to launch instances and help optimize your costs. For more information, see [Auto Scaling groups with multiple instance types and purchase options](https://docs.amazonaws.cn/autoscaling/ec2/userguide/ec2-auto-scaling-mixed-instances-groups.html) in the *Amazon EC2 Auto Scaling User Guide*.

You can create a mixed instances policy for new and existing Auto Scaling groups. You must use a launch template to configure the policy. You cannot use a launch configuration.

There are key differences between Spot Instances and On-Demand Instances:
+ The price for Spot Instances varies based on demand
+ Amazon EC2 can terminate an individual Spot Instance as the availability of, or price for, Spot Instances changes

When a Spot Instance is terminated, Amazon EC2 Auto Scaling group attempts to launch a replacement instance to maintain the desired capacity for the group. 

`MixedInstancesPolicy` is a property of the [AWS::AutoScaling::AutoScalingGroup](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/aws-resource-autoscaling-autoscalinggroup.html) resource.

## Syntax
<a name="aws-properties-autoscaling-autoscalinggroup-mixedinstancespolicy-syntax"></a>

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

### JSON
<a name="aws-properties-autoscaling-autoscalinggroup-mixedinstancespolicy-syntax.json"></a>

```
{
  "[InstancesDistribution](#cfn-autoscaling-autoscalinggroup-mixedinstancespolicy-instancesdistribution)" : InstancesDistribution,
  "[LaunchTemplate](#cfn-autoscaling-autoscalinggroup-mixedinstancespolicy-launchtemplate)" : LaunchTemplate
}
```

### YAML
<a name="aws-properties-autoscaling-autoscalinggroup-mixedinstancespolicy-syntax.yaml"></a>

```
  [InstancesDistribution](#cfn-autoscaling-autoscalinggroup-mixedinstancespolicy-instancesdistribution): 
    InstancesDistribution
  [LaunchTemplate](#cfn-autoscaling-autoscalinggroup-mixedinstancespolicy-launchtemplate): 
    LaunchTemplate
```

## Properties
<a name="aws-properties-autoscaling-autoscalinggroup-mixedinstancespolicy-properties"></a>

`InstancesDistribution`  <a name="cfn-autoscaling-autoscalinggroup-mixedinstancespolicy-instancesdistribution"></a>
The instances distribution.  
*Required*: No  
*Type*: [InstancesDistribution](aws-properties-autoscaling-autoscalinggroup-instancesdistribution.md)  
*Update requires*: [Some interruptions](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-some-interrupt)

`LaunchTemplate`  <a name="cfn-autoscaling-autoscalinggroup-mixedinstancespolicy-launchtemplate"></a>
One or more launch templates and the instance types (overrides) that are used to launch EC2 instances to fulfill On-Demand and Spot capacities.  
*Required*: Yes  
*Type*: [LaunchTemplate](aws-properties-autoscaling-autoscalinggroup-launchtemplate.md)  
*Update requires*: [Some interruptions](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-some-interrupt)