Terraform: Update logger to use AWS data source for AMI resolution

Terraform/locals.tf

@@ -1,4 +1,5 @@
 locals {
   fleet_url  = "https://${aws_instance.logger.public_ip}:8412"
   splunk_url = "https://${aws_instance.logger.public_ip}:8000"
+  ata_url    = "https://${aws_instance.wef.public_ip}"
 }

Terraform/main.tf

@@ -142,7 +142,7 @@ resource "aws_key_pair" "auth" {
 
 resource "aws_instance" "logger" {
   instance_type = "t2.medium"
-  ami           = "ami-0ad16744583f21877"
+  ami           = "${coalesce(data.aws_ami.logger_ami.image_id, var.logger_ami)}"
 
   tags {
     Name = "logger"
@@ -187,8 +187,8 @@ resource "aws_instance" "logger" {
 resource "aws_instance" "dc" {
   instance_type = "t2.medium"
 
-  # Change the below variable to "${var.dc_ami}" if using hardcoded AMIs
+  # Uses the local variable if external data source resolution fails
-  ami = "${data.aws_ami.dc_ami.image_id}"
+  ami = "${coalesce(data.aws_ami.dc_ami.image_id, var.dc_ami)}"
 
   tags {
     Name = "dc.windomain.local"
@@ -206,8 +206,8 @@ resource "aws_instance" "dc" {
 resource "aws_instance" "wef" {
   instance_type = "t2.medium"
 
-  # Change the below variable to "${var.wef_ami}" if using hardcoded AMIs
+  # Uses the local variable if external data source resolution fails
-  ami = "${data.aws_ami.wef_ami.image_id}"
+  ami = "${coalesce(data.aws_ami.wef_ami.image_id, var.wef_ami)}"
 
   tags {
     Name = "wef.windomain.local"
@@ -225,8 +225,8 @@ resource "aws_instance" "wef" {
 resource "aws_instance" "win10" {
   instance_type = "t2.medium"
 
-  # Change the below variable to "${var.win10_ami}" if using hardcoded AMIs
+  # Uses the local variable if external data source resolution fails
-  ami = "${data.aws_ami.win10_ami.image_id}"
+  ami = "${coalesce(data.aws_ami.win10_ami.image_id, var.win10_ami)}"
 
   tags {
     Name = "win10.windomain.local"

Terraform/outputs.tf

@@ -18,16 +18,8 @@ output "win10_public_ip" {
   value = "${aws_instance.win10.public_ip}"
 }
 
-output "latest_dc_ami_id" {
+output "ata_url" {
-  value = "${data.aws_ami.dc_ami.image_id}"
+  value = "${local.ata_url}"
-}
-
-output "latest_wef_ami_id" {
-  value = "${data.aws_ami.wef_ami.image_id}"
-}
-
-output "latest_win10_ami_id" {
-  value = "${data.aws_ami.wef_ami.image_id}"
 }
 
 output "fleet_url" {

Terraform/variables.tf

@@ -46,6 +46,16 @@ variable "external_dns_servers" {
   default     = ["8.8.8.8"]
 }
 
+# Use Data Sources to resolve the AMI-ID for the Ubuntu 16.04 AMI
+data "aws_ami" "logger_ami" {
+  owners = ["099720109477"]
+
+  filter {
+    name   = "name"
+    values = ["ubuntu/images/hvm-ssd/ubuntu-xenial-16.04-amd64-server-20180912"]
+  }
+}
+
 # Use Data Sources to resolve the AMI-ID for the pre-built DC host
 data "aws_ami" "dc_ami" {
   owners = ["505638924199"]
@@ -78,9 +88,15 @@ data "aws_ami" "win10_ami" {
   }
 }
 
-# The logger host uses the Amazon Ubuntu 16.04 image
 # If you are building your own AMIs, replace the default values below with
 # the AMI IDs
+# The default values for us-west-1 have been provied for you
+# You will have to change the default values if you use a different region
+variable "logger_ami" {
+  type    = "string"
+  default = "ami-0ad16744583f21877"
+}
+
 variable "dc_ami" {
   type    = "string"
   default = "ami-03e2df055c632a0dd"