# DesiredConfiguration
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Describes the desired configuration for an instance refresh. 

If you specify a desired configuration, you must specify either a `LaunchTemplate` or a `MixedInstancesPolicy`. 

## Contents
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 ** LaunchTemplate **   
Describes the launch template and the version of the launch template that Amazon EC2 Auto Scaling uses to launch Amazon EC2 instances. For more information about launch templates, see [Launch templates](https://docs.aws.amazon.com/autoscaling/ec2/userguide/launch-templates.html) in the *Amazon EC2 Auto Scaling User Guide*.  
Type: [LaunchTemplateSpecification](API_LaunchTemplateSpecification.md) object  
Required: No

 ** MixedInstancesPolicy **   
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.aws.amazon.com/autoscaling/ec2/userguide/ec2-auto-scaling-mixed-instances-groups.html) in the *Amazon EC2 Auto Scaling User Guide*.  
Type: [MixedInstancesPolicy](API_MixedInstancesPolicy.md) object  
Required: No

## See Also
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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/DesiredConfiguration) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/autoscaling-2011-01-01/DesiredConfiguration) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/autoscaling-2011-01-01/DesiredConfiguration)