> For the complete documentation index, see [llms.txt](https://karansingh.gitbook.io/aws-saa-c02/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://karansingh.gitbook.io/aws-saa-c02/auto-scaling-groups-asg/launch-configurations-and-launch-templates.md).

# Launch Configurations & Launch Templates

## Launch Configurations

* **Instance configuration template** that an **Auto Scaling group uses to launch EC2 instances**.<br>
* Includes:
  * Amazon Machine Image (AMI) ID.
  * Instance type.
  * Key pair.
  * Security groups.
  * And all the other parameters that you use to launch EC2 instances.<br>
* Can **specify your launch configuration with multiple Auto Scaling groups**.<br>
* **Can only specify one launch configuration for an Auto Scaling group at a time**.<br>
* **Can't change 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.

## Launch Templates

* **Similar to a launch configuration but better.**<br>

* Includes:
  * Amazon Machine Image (AMI) ID.
  * Instance type.
  * Key pair.
  * Security groups.
  * And all the other parameters that you use to launch EC2 instances.<br>

* However, defining a launch template instead of a launch configuration **allows you to have multiple versions of a template**.

  * With versioning, you can create a subset of the full set of parameters and then reuse it to create other templates or template versions.<br>
  * For example, you can create a default template that defines common configuration parameters and allow the other parameters to be specified as part of another version of the same template.

* **Launch templates ensure you have access to the latest features and improvements**.<br>

* **Can also use Launch Templates to launch EC2 Instances, whereas with Launch Configurations, you can't**.


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