Auto Healing allows you to select which health check service will automatically perform health checks on your EC2 instances. If an instance fails the health check, it is automatically removed from the Elastigroup and will be replaced with a new instance.
This setting is configurable as part of the "Load balancer" settings in the Compute tab in the Elastigroup configuration. For more information please see: Advanced settings - Compute Tab
You can select the following Health Checks:
None - No replacement will happen - Unhealthy instances will remain in the group!
ELB - Use amazon’s Elastic load balancer health check.
TARGET SET - Use the AWS Application load balancer health check.
EC2 - Use the AWS EC2 Status check.
HCS - Use spotinst health check. You can read more about it here: Spotinst HCS service.
MLB - Use the Multai Load Balancer health check service. You can read more about it here: Introduction to Multai Load Balancer
You can set the following settings for the "Auto Healing" feature:
Health Check Grace Period - Specify the time (in seconds) to allow an instance to boot and applications to fully start before the first health check. If an instance fails the health check after the given delay, it will be terminated and replaced with a new instance.
Unhealthy Duration - Specify the amount of time (in seconds) you want to keep existing instances that are deemed unhealthy before the instance is terminated and replaced with a new one.