Classic Load Balancer has connection draining enabled

# Terraform: Enable connection draining on a Classic Load Balancer
resource "aws_elb" "<example_resource_name>" {
  name               = "<example_resource_name>"
  availability_zones = ["us-east-1a"]

  listener {
    lb_port           = 80
    lb_protocol       = "http"
    instance_port     = 80
    instance_protocol = "http"
  }

  connection_draining = true  # CRITICAL: enables connection draining so existing connections complete
  # connection_draining_timeout can be omitted (defaults to 300s)
}

# CloudFormation: Enable connection draining on a Classic Load Balancer
Resources:
  <example_resource_name>:
    Type: AWS::ElasticLoadBalancing::LoadBalancer
    Properties:
      Listeners:
        - InstancePort: 80
          LoadBalancerPort: 80
          Protocol: HTTP
      AvailabilityZones:
        - us-east-1a
      ConnectionDrainingPolicy:
        Enabled: true  # CRITICAL: turns on connection draining so in-flight requests complete
        # Timeout is optional; default 300s is used if omitted