Welcome
This is the Amazon EC2 Auto Scaling API Reference. Amazon EC2 Auto Scaling is designed to automatically launch and terminate EC2 instances based on user-defined scaling policies, scheduled actions, and health checks. This guide describes the Amazon EC2 Auto Scaling operations that you can call programmatically. For more information about Amazon EC2 Auto Scaling, see the Amazon EC2 Auto Scaling User Guide.
Note
To configure Amazon EC2 instances that are launched by your Auto Scaling group, you can specify a launch template or a launch configuration. We recommend that you use Amazon EC2 launch templates. Launch configurations are included as part of the same API as Auto Scaling groups, but launch templates offer more features. For more information, see Launch templates in the Amazon EC2 Auto Scaling User Guide.
To get started, complete the following tasks:
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Create a launch template using CreateLaunchTemplate.
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Create an Auto Scaling group using CreateAutoScalingGroup.
To make programmatic API calls, you can also use one of the Amazon SDKs,
which consist of libraries and sample code for various programming languages and
platforms. The SDKs provide a convenient way to create programmatic access to Amazon EC2 Auto Scaling.
For example, the SDKs take care of cryptographically signing requests, managing errors,
and retrying requests automatically. For information about the Amazon SDKs, including how
to download and install them, see the Amazon
SDKs
API request rate
Amazon EC2 Auto Scaling uses the token bucket algorithm to implement API throttling. With
this algorithm, your account has a bucket that holds a specific number of tokens. The
number of tokens in the bucket represents your throttling limit at any given second.
Amazon EC2 Auto Scaling throttles API requests based on a shared API bucket. For example, calls to the
DescribeAutoScalingGroups and
DescribeScheduledActions API operations use tokens from the same bucket.
Throttling means that Amazon EC2 Auto Scaling rejects a request because the request exceeds the
service's limit for the number of requests per second. When a request is throttled,
Amazon EC2 Auto Scaling returns a RateExceeded error.
The DescribeAutoScalingGroups API operation might be throttled when retrieving details for an Auto Scaling group that contains many instances. By default, this operation returns details for all instances in the group.
To help prevent throttling, you can set the IncludeInstances parameter to false to exclude instance details from the response.
Additional information
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To specify a custom Amazon Machine Image (AMI) in your launch template, you must first create your AMI from a customized instance. For information on creating a custom AMI, see Create an AMI in the Amazon EC2 User Guide.
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For information about the permissions that are required for Amazon EC2 Auto Scaling, see Granting IAM permissions for Amazon EC2 Auto Scaling actions.
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For information about how to provide network connectivity for instances in an Auto Scaling group, see Provide network connectivity for your Auto Scaling instances using Amazon VPC in the Amazon EC2 Auto Scaling User Guide.
This document was last published on July 11, 2025.