Connection Draining on Elastic Load Balancer

Connection draining is a feature that is enabled by default on Load Balancer created from the AWS console (to be enabled when using CLI or API).

Connection draining ensure that the undergoing activity through open network connections via the load balancer to the EC2 instance. Connection draining prevents from a bad user experience due to incomplete activity when the undelying instance is moved away.

• https://aws.amazon.com/blogs/aws/elb-connection-draining-remove-instances-from-service-with-care/
• http://docs.aws.amazon.com/elasticloadbalancing/latest/classic/config-conn-drain.html