Introduction

This action leverages the AWS EC2 Auto Scaling API to suspend one or more Auto Scaling processes (Launch, Terminate, HealthCheck, ReplaceUnhealthy, AZRebalance, AlarmNotification, ScheduledActions, AddToLoadBalancer, InstanceRefresh) on an Auto Scaling Group for the duration of the experiment.

Use Cases

• Verify how the workload behaves when AZ-Rebalance is unable to redistribute instances after an AZ event.
• Validate that the system tolerates a frozen HealthCheck / ReplaceUnhealthy window.
• Simulate an operational "scaling outage" (no new instances launched) and observe queue/latency growth.

Rollback

The processes that were already suspended on the ASG before the experiment are captured during Prepare.

On Stop the extension resumes only the processes the attack suspended, so any pre-existing suspensions stay intact.

Parameters

Parameter	Description	Default
Duration	How long to keep the processes suspended. Resumed on stop.	60s
Processes	Auto Scaling processes to suspend (multi-select). See AWS docs for effects.	Launch, HealthCheck, ReplaceUnhealthy