LaunchTemplateOverridesArgs

The instance requirements. Amazon EC2 Auto Scaling uses your specified requirements to identify instance types. Then, it uses your On-Demand and Spot allocation strategies to launch instances from these instance types. You can specify up to four separate sets of instance requirements per Auto Scaling group. This is useful for provisioning instances from different Amazon Machine Images (AMIs) in the same Auto Scaling group. To do this, create the AMIs and create a new launch template for each AMI. Then, create a compatible set of instance requirements for each launch template. If you specify `InstanceRequirements`, you can't specify `InstanceType`. The attributes for the instance types for a mixed instances policy. Amazon EC2 Auto Scaling uses your specified requirements to identify instance types. Then, it uses your On-Demand and Spot allocation strategies to launch instances from these instance types. When you specify multiple attributes, you get instance types that satisfy all of the specified attributes. If you specify multiple values for an attribute, you get instance types that satisfy any of the specified values. To limit the list of instance types from which Amazon EC2 Auto Scaling can identify matching instance types, you can use one of the following parameters, but not both in the same request: + `AllowedInstanceTypes` - The instance types to include in the list. All other instance types are ignored, even if they match your specified attributes. + `ExcludedInstanceTypes` - The instance types to exclude from the list, even if they match your specified attributes. You must specify `VCpuCount` and `MemoryMiB`. All other attributes are optional. Any unspecified optional attribute is set to its default. For an example template, see Auto scaling template snippets. For more information, see Creating an Auto Scaling group using attribute-based instance type selection in the Amazon EC2 Auto Scaling User Guide. For help determining which instance types match your attributes before you apply them to your Auto Scaling group, see Preview instance types with specified attributes in the Amazon EC2 User Guide for Linux Instances. `InstanceRequirements` is a property of the `LaunchTemplateOverrides` property of the AWS::AutoScaling::AutoScalingGroup LaunchTemplate property type.

The instance type, such as `m3.xlarge`. You must specify an instance type that is supported in your requested Region and Availability Zones. For more information, see Instance types in the Amazon Elastic Compute Cloud User Guide. You can specify up to 40 instance types per Auto Scaling group.

Provides a launch template for the specified instance type or set of instance requirements. For example, some instance types might require a launch template with a different AMI. If not provided, Amazon EC2 Auto Scaling uses the launch template that's specified in the `LaunchTemplate` definition. For more information, see Specifying a different launch template for an instance type in the Amazon EC2 Auto Scaling User Guide. You can specify up to 20 launch templates per Auto Scaling group. The launch templates specified in the overrides and in the `LaunchTemplate` definition count towards this limit. Specifies a launch template to use when provisioning EC2 instances for an Auto Scaling group. You must specify the following: + The ID or the name of the launch template, but not both. + The version of the launch template. `LaunchTemplateSpecification` is property of the AWS::AutoScaling::AutoScalingGroup resource. It is also a property of the AWS::AutoScaling::AutoScalingGroup LaunchTemplate and AWS::AutoScaling::AutoScalingGroup LaunchTemplateOverrides property types. For information about creating a launch template, see AWS::EC2::LaunchTemplate and Create a launch template for an Auto Scaling group in the Amazon EC2 Auto Scaling User Guide. For examples of launch templates, see Auto scaling template snippets and the Examples section in the `AWS::EC2::LaunchTemplate` resource.

If you provide a list of instance types to use, you can specify the number of capacity units provided by each instance type in terms of virtual CPUs, memory, storage, throughput, or other relative performance characteristic. When a Spot or On-Demand Instance is launched, the capacity units count toward the desired capacity. Amazon EC2 Auto Scaling launches instances until the desired capacity is totally fulfilled, even if this results in an overage. For example, if there are two units remaining to fulfill capacity, and Amazon EC2 Auto Scaling can only launch an instance with a `WeightedCapacity` of five units, the instance is launched, and the desired capacity is exceeded by three units. For more information, see Configure instance weighting for Amazon EC2 Auto Scaling in the Amazon EC2 Auto Scaling User Guide. Value must be in the range of 1-999. If you specify a value for `WeightedCapacity` for one instance type, you must specify a value for `WeightedCapacity` for all of them. Every Auto Scaling group has three size parameters (`DesiredCapacity`, `MaxSize`, and `MinSize`). Usually, you set these sizes based on a specific number of instances. However, if you configure a mixed instances policy that defines weights for the instance types, you must specify these sizes with the same units that you use for weighting instances.