AWS NLB

Abstract

---

• AWS’s offering of Network Load Balancer
• Uses NAT to Proxy the incoming/outgoing traffic
• Listener can only be either TCP, TCP_UDP, TLS or UDP
• Target Group can only use Network Protocol TCP, TCP_UDP, TLS or UDP (Based on AWS experience)
• Health Check can use Network Protocol TCP, HTTP or HTTPS

Tips

---

Obtain Private IPs dynamically using Terraform

data "aws_network_interface" "nlb_private_ip" {
	for_each = toset(var.private_subnet_ids)
	
	filter {
		name = "description"
		values = ["ELB ${aws_lb.network.arn_suffix}"]
	}
	
	filter {
		name = "subnet-id"
		values = [each.value]
	}
}
 
resource "aws_lb_target_group_attachment" "nlb" {
	for_each = toset(var.private_subnet_ids)
	
	target_group_arn = aws_lb_target_group.nlb.arn
	
	target_id = data.aws_network_interface.nlb_private_ip[each.key].private_ip
	
	port = 443
}

Caution

• We are creating the resources based on var.private_subnet_ids. Thus we need to Dependencies