# Add-ons

In order to support various unique functions for different cloud providers, we provide add-ons.

## AWS  <a href="#aws" id="aws"></a>

The ALM-agent enables you to perform specific actions when Auto Scaling Instances or Spot Instances are terminated.

### How ALM Agent Works

* Deregisters the instance from the load balancer.
  * After the instance is deregistered, it no longer receives traffic from the load balancer.
* Executes the specified script.
  * If you put the script named `pre_shutdown.sh` under the root (`/`) folder in the Docker Image, the ALM-agent executes the script.

### Conditions

* Auto Scaling puts the instance into `Terminating:Wait`.
* Amazon EC2 will interrupt Spot Instances.