Parametrize EC2 Instance Module based on IAM Role

modules/aws/EC2-Instance/ec2_instance.tf

@@ -26,7 +26,7 @@ resource "aws_instance" "ec2_instance" {
 
   tags = local.ec2_tags
 
-  iam_instance_profile = aws_iam_instance_profile.iam_instance_profile.name
+  iam_instance_profile = aws_iam_instance_profile.iam_instance_profile[0].name
 
   network_interface {
     device_index         = 0

modules/aws/EC2-Instance/iam_role.tf

@@ -35,7 +35,7 @@ resource "aws_iam_policy" "session_manager_policy" {
 
 resource "aws_iam_role" "iam_role" {
   name = join("-", [var.project, var.application, var.environment, var.region, "ec2-iam-role"])
-
+  count = var.ec2_iam_role_arn != null ? 0 : 1
   assume_role_policy = <<POLICY
 {
   "Version": "2012-10-17",
@@ -56,19 +56,20 @@ POLICY
 
 resource "aws_iam_instance_profile" "iam_instance_profile" {
   name = join("-", [var.project, var.application, var.environment, var.region, "ec2-instance-profile"])
-  role = aws_iam_role.iam_role.name
+  count = var.ec2_iam_role_arn != null ? 0 : 1
+  role = aws_iam_role.iam_role[0].name
 
   depends_on = [aws_iam_role.iam_role]
 }
 
 resource "aws_iam_role_policy_attachment" "instance_connect" {
   count      = var.enable_instance_connect == true ? 1 : 0
-  role       = aws_iam_role.iam_role.name
+  role       = aws_iam_role.iam_role[0].name
   policy_arn = "arn:aws:iam::aws:policy/service-role/AmazonSSMManagedInstanceCore"
 }
 
 resource "aws_iam_role_policy_attachment" "session_manager" {
   count      = var.enable_session_manager == true ? 1 : 0
-  role       = aws_iam_role.iam_role.name
+  role       = aws_iam_role.iam_role[0].name
   policy_arn = aws_iam_policy.session_manager_policy[0].arn
 }

modules/aws/EC2-Instance/variables.tf

@@ -133,3 +133,7 @@ variable "user_data" {
   description = "User data to be passed to the EC2 instance"
   default     = null
 }
+variable "ec2_iam_role_arn" {
+  type        = string
+  description = "IAM Role ARN for the EC2"
+}