Amazon EC2 Auto Scaling
API Reference (API Version 2011-01-01)

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InstancesDistribution

Describes an instances distribution for an Auto Scaling group with MixedInstancesPolicy.

The instances distribution specifies the distribution of On-Demand Instances and Spot Instances, the maximum price to pay for Spot Instances, and how the Auto Scaling group allocates instance types to fulfill On-Demand and Spot capacity.

When you update SpotAllocationStrategy, SpotInstancePools, or SpotMaxPrice, this update action does not deploy any changes across the running Amazon EC2 instances in the group. Your existing Spot Instances continue to run as long as the maximum price for those instances is higher than the current Spot price. When scale out occurs, Amazon EC2 Auto Scaling launches instances based on the new settings. When scale in occurs, Amazon EC2 Auto Scaling terminates instances according to the group's termination policies.

Contents

OnDemandAllocationStrategy

Indicates how to allocate instance types to fulfill On-Demand capacity.

The only valid value is prioritized, which is also the default value. This strategy uses the order of instance type overrides for the LaunchTemplate to define the launch priority of each instance type. The first instance type in the array is prioritized higher than the last. If all your On-Demand capacity cannot be fulfilled using your highest priority instance, then the Auto Scaling groups launches the remaining capacity using the second priority instance type, and so on.

Type: String

Pattern: [\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*

Required: No

OnDemandBaseCapacity

The minimum amount of the Auto Scaling group's capacity that must be fulfilled by On-Demand Instances. This base portion is provisioned first as your group scales.

The default value is 0. If you leave this parameter set to 0, On-Demand Instances are launched as a percentage of the Auto Scaling group's desired capacity, per the OnDemandPercentageAboveBaseCapacity setting.

Note

An update to this setting means a gradual replacement of instances to maintain the specified number of On-Demand Instances for your base capacity. When replacing instances, Amazon EC2 Auto Scaling launches new instances before terminating the old ones.

Type: Integer

Required: No

OnDemandPercentageAboveBaseCapacity

Controls the percentages of On-Demand Instances and Spot Instances for your additional capacity beyond OnDemandBaseCapacity. The range is 0–100.

The default value is 100. If you leave this parameter set to 100, the percentages are 100% for On-Demand Instances and 0% for Spot Instances.

Note

An update to this setting means a gradual replacement of instances to maintain the percentage of On-Demand Instances for your additional capacity above the base capacity. When replacing instances, Amazon EC2 Auto Scaling launches new instances before terminating the old ones.

Type: Integer

Required: No

SpotAllocationStrategy

Indicates how to allocate instances across Spot Instance pools.

If the allocation strategy is lowest-price, the Auto Scaling group launches instances using the Spot pools with the lowest price, and evenly allocates your instances across the number of Spot pools that you specify. If the allocation strategy is capacity-optimized, the Auto Scaling group launches instances using Spot pools that are optimally chosen based on the available Spot capacity.

The default Spot allocation strategy for calls that you make through the API, the AWS CLI, or the AWS SDKs is lowest-price. The default Spot allocation strategy for the AWS Management Console is capacity-optimized.

Valid values: lowest-price | capacity-optimized

Type: String

Pattern: [\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*

Required: No

SpotInstancePools

The number of Spot Instance pools across which to allocate your Spot Instances. The Spot pools are determined from the different instance types in the Overrides array of LaunchTemplate. The range is 1–20. The default value is 2.

Valid only when the Spot allocation strategy is lowest-price.

Type: Integer

Required: No

SpotMaxPrice

The maximum price per unit hour that you are willing to pay for a Spot Instance. If you leave the value of this parameter blank (which is the default), the maximum Spot price is set at the On-Demand price.

To remove a value that you previously set, include the parameter but leave the value blank.

Type: String

Length Constraints: Minimum length of 0. Maximum length of 255.

Required: No

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following:

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