Amazon EC2 Auto Scaling helps you ensure that you have the correct number of Amazon EC2 instances available to handle the load for your application. You create collections of EC2 instances, called Auto Scaling groups. You can specify the minimum number of instances in each Auto Scaling group, and Amazon EC2 Auto Scaling ensures that your group never goes below this size. You can specify the maximum number of instances in each Auto Scaling group, and Amazon EC2 Auto Scaling ensures that your group never goes above this size. If you specify the desired capacity, either when you create the group or at any time thereafter, Amazon EC2 Auto Scaling ensures that your group has this many instances. If you specify scaling policies, then Amazon EC2 Auto Scaling can launch or terminate instances as demand on your application increases or decreases.
For example, the following Auto Scaling group has a minimum size of one instance, a desired capacity of two instances, and a maximum size of four instances. The scaling policies that you define adjust the number of instances, within your minimum and maximum number of instances, based on the criteria that you specify.
The following table describes the key components of Amazon EC2 Auto Scaling.
Pricing for Amazon EC2 Auto Scaling
There are no additional fees with Amazon EC2 Auto Scaling, so it's easy to try it out and see how it can benefit your AWS architecture. You only pay for the AWS resources (for example, EC2 instances, EBS volumes, and CloudWatch alarms) that you use.
Get started
To begin, complete the tutorial to create an Auto Scaling group and see how it responds when an instance in that group terminates.
Related services
To automatically distribute incoming application traffic across multiple instances in your Auto Scaling group, use Elastic Load Balancing. For more information, see .
To monitor your Auto Scaling groups and instance utilization data, use Amazon CloudWatch. For more information, see .
To configure auto scaling for scalable resources for Amazon Web Services beyond Amazon EC2, see the .
Work with Auto Scaling groups
You can create, access, and manage your Auto Scaling groups using any of the following interfaces:
AWS Management Console – Provides a web interface that you can use to access your Auto Scaling groups. If you've signed up for an AWS account, you can access your Auto Scaling groups by signing into the AWS Management Console, using the search box on the navigation bar to search for Auto Scaling groups, and then choosing Auto Scaling groups.
AWS Command Line Interface (AWS CLI) – Provides commands for a broad set of AWS services, and is supported on Windows, macOS, and Linux. To get started, see . For more information, see in the AWS CLI Command Reference.
AWS Tools for Windows PowerShell – Provides commands for a broad set of AWS products for those who script in the PowerShell environment. To get started, see the . For more information, see the .
AWS SDKs – Provides language-specific API operations and takes care of many of the connection details, such as calculating signatures, handling request retries, and handling errors. For more information, see .
Query API – Provides low-level API actions that you call using HTTPS requests. Using the Query API is the most direct way to access AWS services. However, it requires your application to handle low-level details such as generating the hash to sign the request, and handling errors. For more information, see the .
AWS CloudFormation – Supports creating Auto Scaling groups using CloudFormation templates. For more information, see .
Groups
Your EC2 instances are organized into groups so that they can be treated as a logical unit for the purposes of scaling and management. When you create a group, you can specify its minimum, maximum, and, desired number of EC2 instances. For more information, see .
Configuration templates
Your group uses a launch template, or a launch configuration (not recommended, offers fewer features), as a configuration template for its EC2 instances. You can specify information such as the AMI ID, instance type, key pair, security groups, and block device mapping for your instances. For more information, see and .
Scaling options
Amazon EC2 Auto Scaling provides several ways for you to scale your Auto Scaling groups. For example, you can configure a group to scale based on the occurrence of specified conditions (dynamic scaling) or on a schedule. For more information, see .
