How do I reboot an instance in an Amazon EC2 Auto Scaling group?

Last updated: 2022-08-03

My Amazon Elastic Compute Cloud (Amazon EC2) instance is part of an Amazon EC2 Auto Scaling group. I want to reboot the instance without Amazon EC2 Auto Scaling terminating it due to health check failure. How can I do this?

Short description

If you stop and start an instance in the InService state in an Amazon EC2 Auto Scaling group, then Amazon EC2 Auto Scaling terminates the instance. Amazon EC2 Auto Scaling does this because the instance fails health checks when it reaches the Stopping or Stopped states during a reboot.

Use any of the following procedures to start and stop the instance without Amazon EC2 Auto Scaling marking the instance as Unhealthy and then terminating it:

  • Put the instance into the Standby state
  • Detach the instance from the group
  • Suspend the health check process

Resolution

Put the instance into the Standby state

To reboot an instance in an Amazon EC2 Auto Scaling group, first put the instance into the Standby state. You do this because Amazon EC2 Auto Scaling doesn’t perform health checks on instances in the Standby state. Choose this option if you need the Amazon EC2 Auto Scaling group to manage the instance throughout the process, as an Auto Scaling group will still manage instances in a Standby state.

Follow these steps to put the instance into a Standby state, reboot the instance, and then return the instance to service:

  1. Open the Amazon EC2 console.
  2. In the navigation pane, under Auto Scaling, choose Auto Scaling Groups.
  3. Select the group of the instance that you want to reboot. On the Instances view, select the instance you want to reboot.
  4. Choose Actions, then choose Set to Standby. On the Set to Standby page, choose Set to Standby.
  5. In the navigation pane, under Instances, choose Instances.
    Note: Optionally, you can choose Add a new instance to the Auto Scaling group to balance the load to maintain the group capacity.
  6. Select the instance you set to the Standby state. Choose Actions, choose Instance State, and then choose Reboot.
  7. Select the instance again, and then choose the Status Checks view. Confirm that your System Status Checks and Instance Status Checks are passing.
  8. In the navigation pane, under Auto Scaling, choose Auto Scaling Groups.
  9. Select the group of the instance that you set to the Standby state.
  10. Select the instance that you rebooted. Choose Actions, and then choose Set to InService. On the Set to InService page, choose Set to InService.

Detach the instance from the group

You can detach an instance from an Amazon EC2 Auto Scaling group to manage the instance independently of its Amazon EC2 Auto Scaling group. After you reboot the instance, you can attach the instance to an Amazon EC2 Auto Scaling group again or you can leave the instance unattached.

Follow these steps to detach the instance from the Amazon EC2 Auto Scaling group, reboot the instance, and then attach the instance to the group again:

  1. Open the Amazon EC2 console.
  2. In the navigation pane, under Auto Scaling, choose Auto Scaling Groups.
  3. Select the group of the instance that you want to reboot. On the Instances view, select the instance.
  4. Choose Actions, then choose Detach.
  5. On the Detach Instance page, choose Detach Instance.
    Note: Optionally, you can choose Add a new instance to the Auto Scaling group to balance the load to replace the instance you’re detaching.
  6. In the navigation pane, under Instances, choose Instances.
  7. Select the instance that you detached. Choose Actions, choose Instance State, and then choose Reboot.
  8. Select the instance, and then choose the Status Checks view. Confirm that the System Status Checks and Instance Status Checks are passing.
  9. Select the instance, choose Actions, choose Instance Settings, and then choose Attach to Auto Scaling Group.
  10. For Attach to Auto Scaling Group, under Attach an instance to, choose an existing Auto Scaling group. Select or search for the group that you detached the instance from. Then, choose Attach.

Suspend the health check process

You can suspend the health check process for your Auto Scaling group to reboot instances without Amazon EC2 Auto Scaling terminating the instances.

Warning: Suspending a process affects all instances in an Auto Scaling group. Until you resume the process, Amazon EC2 Auto Scaling doesn't replace any unhealthy instances. If you need Amazon EC2 Auto Scaling to perform health checks on remaining instances, choose one of the previous options.

Follow these steps to suspend the health check process for your group, reboot an instance, and then resume the health check process for the group:

  1. Open the Amazon EC2 console.
  2. In the navigation pane, under Auto Scaling, choose Auto Scaling Groups.
  3. Select the group of the instance that you want to reboot.
  4. On the Details view, choose Edit.
  5. Under Suspended Processes, select HealthCheck. Then, choose Save.
  6. In the navigation pane, under Instances, and then choose Instances.
    Note: Optionally, you can choose Add a new instance to the Auto Scaling group to balance the load to maintain the group capacity.
  7. Select the instance that you reboot. Choose Actions, choose Instance State, and then choose Reboot.
  8. Select the instance, and then choose the Status Checks view. Confirm that the System Status Checks and Instance Status Checks are passing.
  9. In the navigation pane, under Auto Scaling, choose Auto Scaling Groups.
  10. Select the group of the instance that you rebooted.
  11. On the Details view, choose Edit. Under Suspended Processes, remove HealthCheck, and then choose Save.