Connection Draining/Deregistration Delay

• For CLBs, it is called Connection Draining.

  • But, for Target Groups (so ALBs and NLBs), it called Deregistration Delay.

• To ensure that a Load Balancer stops sending requests to instances that are de-registering or unhealthy, while keeping the existing connections open, use connection draining.

  • This enables the load balancer to complete in-flight requests made to instances that are de-registering or unhealthy.

• When you enable connection draining, you can specify a maximum time for the load balancer to keep connections alive before reporting the instance as de-registered.

  • The maximum timeout value can be set between 1 and 3,600 seconds (the default is 300 seconds).

    • When the maximum time limit is reached, the load balancer forcibly closes connections to the de-registering instance.