Suspend and resume Amazon EC2 Auto Scaling processes - Amazon EC2 Auto Scaling
Types of processes

Suspend and resume Amazon EC2 Auto Scaling processes

This topic describes how to suspend and then resume one or more of the processes for your Auto Scaling group to temporarily disable certain operations.

Suspending processes can be useful when you need to investigate or troubleshoot an issue without interference from scaling policies or scheduled actions. It also helps prevent Amazon EC2 Auto Scaling from marking instances unhealthy and replacing them while you are making changes to your Auto Scaling group.

Topics
Note

In addition to suspensions that you initiate, Amazon EC2 Auto Scaling can also suspend processes for Auto Scaling groups that repeatedly fail to launch instances. This is known as an administrative suspension. An administrative suspension most commonly applies to Auto Scaling groups that have been trying to launch instances for over 24 hours but have not succeeded in launching any instances. You can resume processes that were suspended by Amazon EC2 Auto Scaling for administrative reasons.

Types of processes

The suspend-resume feature supports the following processes:

  • Launch – Adds instances to the Auto Scaling group when the group scales out, or when Amazon EC2 Auto Scaling chooses to launch instances for other reasons, such as when it adds instances to a warm pool.

  • Terminate – Removes instances from the Auto Scaling group when the group scales in, or when Amazon EC2 Auto Scaling chooses to terminate instances for other reasons, such as when an instance is terminated for exceeding its maximum lifetime duration or failing a health check.

  • AddToLoadBalancer – Adds instances to the attached load balancer target group or Classic Load Balancer when they are launched. For more information, see Use Elastic Load Balancing; to distribute incoming application traffic in your Auto Scaling group .

  • AlarmNotification – Accepts notifications from CloudWatch alarms that are associated with dynamic scaling policies. For more information, see Dynamic scaling for Amazon EC2 Auto Scaling.

  • AZRebalance – Balances the number of EC2 instances in the group evenly across all of the specified Availability Zones when the group becomes unbalanced, for example, when a previously unavailable Availability Zone returns to a healthy state. For more information, see Rebalancing activities.

  • HealthCheck – Checks the health of the instances and marks an instance as unhealthy if Amazon EC2 or Elastic Load Balancing tells Amazon EC2 Auto Scaling that the instance is unhealthy. This process can override the health status of an instance that you set manually. For more information, see Health checks for instances in an Auto Scaling group.

  • InstanceRefresh – Terminates and replaces instances using the instance refresh feature. For more information, see Use an instance refresh to update instances in an Auto Scaling group.

  • ReplaceUnhealthy – Terminates instances that are marked as unhealthy and then creates new instances to replace them. For more information, see Health checks for instances in an Auto Scaling group.

  • ScheduledActions – Performs the scheduled scaling actions that you create or that are created for you when you create an AWS Auto Scaling scaling plan and turn on predictive scaling. For more information, see Scheduled scaling for Amazon EC2 Auto Scaling.