From 885b8f8bd178600c3a44f3f55d871ac469c1ea9e Mon Sep 17 00:00:00 2001
From: mcgin314 <luther.coleman.mcginty@census.gov>
Date: Mon, 7 Oct 2024 17:22:47 -0400
Subject: [PATCH] Retrieve load balancer dns

---
 aws_data.tf          | 11 +++++++++++
 load_balancer_dns.sh | 15 +++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100755 load_balancer_dns.sh

diff --git a/aws_data.tf b/aws_data.tf
index 050df9e..e735d7b 100644
--- a/aws_data.tf
+++ b/aws_data.tf
@@ -21,3 +21,14 @@ data "aws_vpc" "dummy_vpc" {
     values = ["vpc0-dummy"]
   }
 }
+
+# We need to lookup the DNS entry for the istio ingress load balancer created by the tfmod-istio
+# We then use this value to create the CNAME record for cluster app/api addressing
+data "external" "load_balancer_dns" {
+  program = ["bash", "${path.module}/load_balancer_dns.sh", format("%v-%v", var.cluster_name, "istio-ingress")]
+}
+
+# format("%v-%v", var.cluster_name, "metrics-server")
+output "load_balancer_dns" {
+  value = data.external.load_balancer_dns.result.dnsName
+}
\ No newline at end of file
diff --git a/load_balancer_dns.sh b/load_balancer_dns.sh
new file mode 100755
index 0000000..744a801
--- /dev/null
+++ b/load_balancer_dns.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+# Script to get Load Balancer DNS Name based on the tag Name
+
+LB_NAME=$1
+
+lb_arn=$(for i in $(aws elbv2 describe-load-balancers --query 'LoadBalancers[].LoadBalancerArn' --output text); \
+do aws elbv2 describe-tags --resource-arns "$i" --query "TagDescriptions[?Tags[?Key=='Name' &&Value=='$LB_NAME']].ResourceArn" --output text ;done)
+
+if [ -z "$lb_arn" ]; then
+  lb_arn="no_arn_exists_for_this_lb_name"
+fi
+
+dns_name=$(aws elbv2 describe-load-balancers --load-balancer-arns $lb_arn --query 'LoadBalancers[].DNSName' --output text)
+
+jq -n --arg dnsName "$dns_name" '{"dnsName":$dnsName}'
\ No newline at end of file