Combine NLBs to use one NLB per cluster

* Simplify clusters to come with a single NLB
* Listen for apiserver traffic on port 6443 and forward
to controllers (with healthy apiserver)
* Listen for ingress traffic on ports 80/443 and forward
to workers (with healthy ingress controller)
* Reduce cost of default clusters by 1 NLB ($18.14/month)
* Keep using CNAME records to the `ingress_dns_name` NLB and
the nginx-ingress addon for Ingress (up to a few million RPS)
* Users with heavy traffic (many million RPS) can create their
own separate NLB(s) for Ingress and use the new output worker
target groups
* Fix issue where additional worker pools come with an
extraneous network load balancer

aws/container-linux/kubernetes/workers/ingress.tf

@@ -1,39 +1,4 @@
-# Network Load Balancer for Ingress
-resource "aws_lb" "ingress" {
-  name               = "${var.name}-ingress"
-  load_balancer_type = "network"
-  internal           = false
-
-  subnets = ["${var.subnet_ids}"]
-
-  enable_cross_zone_load_balancing = true
-}
-
-# Forward HTTP traffic to workers
-resource "aws_lb_listener" "ingress-http" {
-  load_balancer_arn = "${aws_lb.ingress.arn}"
-  protocol          = "TCP"
-  port              = 80
-
-  default_action {
-    type             = "forward"
-    target_group_arn = "${aws_lb_target_group.workers-http.arn}"
-  }
-}
-
-# Forward HTTPS traffic to workers
-resource "aws_lb_listener" "ingress-https" {
-  load_balancer_arn = "${aws_lb.ingress.arn}"
-  protocol          = "TCP"
-  port              = 443
-
-  default_action {
-    type             = "forward"
-    target_group_arn = "${aws_lb_target_group.workers-https.arn}"
-  }
-}
-
-# Network Load Balancer target groups of instances
+# Target groups of instances for use with load balancers
 
 resource "aws_lb_target_group" "workers-http" {
   name        = "${var.name}-workers-http"

aws/container-linux/kubernetes/workers/outputs.tf

@@ -1,4 +1,9 @@
-output "ingress_dns_name" {
-  value       = "${aws_lb.ingress.dns_name}"
-  description = "DNS name of the network load balancer for distributing traffic to Ingress controllers"
+output "target_group_http_arn" {
+  description = "ARN of a target group of workers for HTTP traffic"
+  value = "${aws_lb_target_group.workers-http.arn}"
+}
+
+output "target_group_https_arn" {
+  description = "ARN of a target group of workers for HTTPS traffic"
+  value = "${aws_lb_target_group.workers-https.arn}"
 }