invalid ARN error on terraform when creating eks cluster - amazon-web-services

Question

**resource "aws_iam_role" "eks_role" {
name = "eks_role"
assume_role_policy = <<POLICY
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"Service": "eks.amazonaws.com"
},
"Action": "sts:AssumeRole"
}
]
}
POLICY
}
resource "aws_iam_role_policy_attachment" "AmazonEKSClusterPolicy" {
policy_arn = "arn:aws:iam::aws:policy/AmazonEKSClusterPolicy"
role = "aws_iam_role.eks_role.name"
}
resource "aws_iam_role_policy_attachment" "AmazonEKSServicePolicy" {
policy_arn = "arn:aws:iam::aws:policy/AmazonEKSServicePolicy"
role = "aws_iam_role.eks_role.name"
}
resource "aws_eks_cluster" "t3_eks" {
name = "t3_eks"
role_arn = "aws_iam_role.eks_role.arn"
vpc_config {
security_group_ids = var.sg
subnet_ids = var.subnets
endpoint_private_access = false
endpoint_public_access = true
}
depends_on = [
aws_iam_role_policy_attachment.AmazonEKSClusterPolicy,
aws_iam_role_policy_attachment.AmazonEKSServicePolicy,
]
}**
Error message
Error: "role_arn" (aws_iam_role.eks_role.arn) is an invalid ARN: arn: invalid prefix
on EKS\main.tf line 30, in resource "aws_eks_cluster" "t3_eks":
30: resource "aws_eks_cluster" "t3_eks" {
Please could someone guide as to what could be wrong?

Answer 1

Quotes are important with terraform. In 0.12 the quoted string "aws_iam_role.eks_role.arn" is just a string. In order for it to be interpolated as an actual variable, you need to remove the quotes:
resource "aws_eks_cluster" "t3_eks" {
name = "t3_eks"
role_arn = aws_iam_role.eks_role.arn
It is also possible to interpolate a variable inside of a string, which is required for terraform 0.11 or older:
resource "aws_eks_cluster" "t3_eks" {
name = "t3_eks"
role_arn = "${aws_iam_role.eks_role.arn}"