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Auto Scaling
User Guide

Creating an Auto Scaling Group

When you create an Auto Scaling group, you must specify the launch configuration to use for launching the instances, and the minimum number of instances your group must maintain at all times. To get the most out of your Auto Scaling group, you should also specify the following:

  • Availability Zones or subnets. It is often a good idea to build or modify your applications in AWS to use more than one Availability Zone. If your Auto Scaling group operates within a VPC, you can alternatively specify which subnets you want Auto Scaling to use.

  • Metrics and health checks. An effective Auto Scaling group uses metrics to determine when it should launch or terminate instances. In addition, it's helpful to define health checks which Auto Scaling uses to determine if an instance is healthy or, if not, if Auto Scaling should terminate the instance and replace it.

Alternatively, you can create an Auto Scaling group using an EC2 instance instead of a launch configuration. For more information, see Creating an Auto Scaling Group Using an EC2 Instance.

Prerequisites

Create a launch configuration. For more information, see Creating a Launch Configuration.

To create an Auto Scaling group using the console

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

  2. On the navigation bar at the top of the screen, select the same region that you used when you created the launch configuration.

  3. On the navigation pane, under Auto Scaling, choose Auto Scaling Groups.

  4. Choose Create Auto Scaling group.

  5. On the Create Auto Scaling Group page, select Create an Auto Scaling group from an existing launch configuration, select a launch configuration, and then choose Next Step.

    Note

    If you do not have any launch configurations, you're first prompted to create one before you can continue with the steps to create an Auto Scaling group.

  6. On the Configure Auto Scaling group details page, do the following:

    1. For Group name, type a name for your Auto Scaling group.

    2. For Group size, type the initial number of instances for your Auto Scaling group.

    3. If you selected an instance type for your launch configuration that requires a VPC, such as a T2 instance, you must select a VPC for Network. Otherwise, if your account supports EC2-Classic and you selected an instance type that doesn't require a VPC, you can choose either Launch into EC2-Classic or a VPC.

    4. If you selected a VPC in the previous step, select one or more subnets from Subnet. If you selected EC2-Classic instead, select one or more Availability Zones from Availability Zone(s).

    5. Choose Next: Configure scaling policies.

  7. On the Configure scaling policies page, select one of the following options, and then choose Review:

    • To manually adjust the size of the Auto Scaling group as needed, select Keep this group at its initial size. For more information, see Manual Scaling.

    • To automatically adjust the size of the Auto Scaling group based on criteria that you specify, select Use scaling policies to adjust the capacity of this group and follow the directions. For more information, see Configure Scaling Policies.

  8. (Optional) To add tags now, choose Edit tags and complete the following steps. Alternatively, you can add tags later on. For more information, see Tagging Auto Scaling Groups and Instances.

    1. For Key and Value, type the key and the value for your first tag.

    2. Keep Tag New Instances selected if you want Auto Scaling to propagate the tag to the instances launched by your Auto Scaling group.

    3. Choose Add tag to add additional tags, and then type keys and values for the tags.

    4. Choose Review.

  9. On the Review page, choose Create Auto Scaling group.

  10. On the Auto Scaling group creation status page, choose Close.

To create an Auto Scaling group using the command line

You can use one of the following commands: