Auto Scaling launch configurations
Important
We provide information about launch configurations for customers who have not yet migrated from launch configurations to launch templates. For information about migrating your Auto Scaling groups to launch templates, see Migrate your Auto Scaling groups to launch templates.
A launch configuration is an instance configuration template that an Auto Scaling group uses to launch EC2 instances. When you create a launch configuration, you specify information for the instances. Include the ID of the Amazon Machine Image (AMI), the instance type, a key pair, one or more security groups, and a block device mapping. If you've launched an EC2 instance before, you specified the same information in order to launch the instance.
You can specify your launch configuration with multiple Auto Scaling groups. However, you can only specify one launch configuration for an Auto Scaling group at a time, and you can't modify a launch configuration after you've created it. To change the launch configuration for an Auto Scaling group, you must create a launch configuration and then update your Auto Scaling group with it.