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:

1. Create a launch template using CreateLaunchTemplate.

2. Create an Auto Scaling group using CreateAutoScalingGroup.

To make programmatic API calls, you can also use one of the AWS 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 AWS SDKs, including how
to download and install them, see the AWS
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. For more information, see My Auto
Scaling API calls are getting throttled. What can I do to avoid this? in the
AWS Knowledge Center.

Additional information

• 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 for Linux Instances.

• For information about the permissions that are required for Amazon EC2 Auto Scaling, see
  Granting IAM permissions for Amazon EC2 Auto Scaling
  actions.

• 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 May 5, 2023.