From c5c6231574923dd8f83fcb7612bf342521d37f9a Mon Sep 17 00:00:00 2001
From: "W. Trevor King" <wking@tremily.us>
Date: Mon, 17 Sep 2018 21:58:35 -0700
Subject: [PATCH] modules/aws/bootstrap: Add elbs_length

To work around Terraform's limitations on length() of computed lists
at plan-time [1].  By avoiding the generated resources and just
computing the number of elastic load-balancers based on our input
counts, we avoid confusing Terraform and getting [2]:

  * module.bootstrap.aws_elb_attachment.bootstrap:
    aws_elb_attachment.bootstrap: value of 'count' cannot be computed

The value of 2 comes from:

* One internal LB (either aws_elb.api_internal or aws_elb.api_external) and
* One aws_elb.console.

[1]: https://github.com/hashicorp/terraform/issues/12570#issuecomment-318414280
[2]: https://storage.googleapis.com/origin-ci-test/pr-logs/pull/openshift_installer/268/pull-ci-openshift-installer-e2e-aws/316/build-log.txt
---
 modules/aws/bootstrap/main.tf      | 2 +-
 modules/aws/bootstrap/variables.tf | 4 ++++
 modules/aws/vpc/outputs.tf         | 4 ++++
 steps/infra/aws/main.tf            | 1 +
 4 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/modules/aws/bootstrap/main.tf b/modules/aws/bootstrap/main.tf
index c83b0cefecd..1dec9bc5949 100644
--- a/modules/aws/bootstrap/main.tf
+++ b/modules/aws/bootstrap/main.tf
@@ -121,7 +121,7 @@ resource "aws_instance" "bootstrap" {
 }
 
 resource "aws_elb_attachment" "bootstrap" {
-  count    = "${length(var.elbs)}"
+  count    = "${var.elbs_length}"
   elb      = "${var.elbs[count.index]}"
   instance = "${aws_instance.bootstrap.id}"
 }
diff --git a/modules/aws/bootstrap/variables.tf b/modules/aws/bootstrap/variables.tf
index f67481c01fc..fd7b1726142 100644
--- a/modules/aws/bootstrap/variables.tf
+++ b/modules/aws/bootstrap/variables.tf
@@ -24,6 +24,10 @@ variable "elbs" {
   description = "Elastic load balancer IDs to attach to the bootstrap node."
 }
 
+variable "elbs_length" {
+  description = "The length of the 'elbs' variable, to work around https://github.com/hashicorp/terraform/issues/12570."
+}
+
 variable "iam_role" {
   type        = "string"
   default     = ""
diff --git a/modules/aws/vpc/outputs.tf b/modules/aws/vpc/outputs.tf
index cab4d40f9b6..70647446172 100644
--- a/modules/aws/vpc/outputs.tf
+++ b/modules/aws/vpc/outputs.tf
@@ -46,6 +46,10 @@ output "aws_lbs" {
   value = ["${compact(concat(aws_elb.api_internal.*.id, list(aws_elb.console.id), aws_elb.api_external.*.id))}"]
 }
 
+output "aws_lbs_length" {
+  value = "2"
+}
+
 output "aws_elb_api_external_dns_name" {
   value = "${element(concat(aws_elb.api_external.*.dns_name, list("")), 0)}"
 }
diff --git a/steps/infra/aws/main.tf b/steps/infra/aws/main.tf
index 0035320e40b..55b26035d89 100644
--- a/steps/infra/aws/main.tf
+++ b/steps/infra/aws/main.tf
@@ -23,6 +23,7 @@ module "bootstrap" {
   bucket                      = "${aws_s3_bucket.tectonic.bucket}"
   cluster_name                = "${var.tectonic_cluster_name}"
   elbs                        = "${module.vpc.aws_lbs}"
+  elbs_length                 = "${module.vpc.aws_lbs_length}"
   iam_role                    = "${var.tectonic_aws_master_iam_role_name}"
   ignition                    = "${local.ignition_bootstrap}"
   subnet_id                   = "${module.vpc.master_subnet_ids[0]}"