fix: Add vpc_config.cluster_security_group output as primary cluster security group id (#828)

Author: slimm609

README.md

@@ -219,7 +219,8 @@ MIT Licensed. See [LICENSE](https://github.com/terraform-aws-modules/terraform-a
 | cluster\_iam\_role\_name | IAM role name of the EKS cluster. |
 | cluster\_id | The name/id of the EKS cluster. |
 | cluster\_oidc\_issuer\_url | The URL on the EKS cluster OIDC Issuer |
-| cluster\_security\_group\_id | Security group ID attached to the EKS cluster. |
+| cluster\_primary\_security\_group\_id | The cluster primary security group ID created by the EKS cluster on 1.14 or later. Referred to as 'Cluster security group' in the EKS console. |
+| cluster\_security\_group\_id | Security group ID attached to the EKS cluster. On 1.14 or later, this is the 'Additional security groups' in the EKS console. |
 | cluster\_version | The Kubernetes server version for the EKS cluster. |
 | config\_map\_aws\_auth | A kubernetes configuration to authenticate to this EKS cluster. |
 | kubeconfig | kubectl config file contents for this EKS cluster. |

outputs.tf

@@ -24,7 +24,7 @@ output "cluster_version" {
 }
 
 output "cluster_security_group_id" {
-  description = "Security group ID attached to the EKS cluster."
+  description = "Security group ID attached to the EKS cluster. On 1.14 or later, this is the 'Additional security groups' in the EKS console."
   value       = local.cluster_security_group_id
 }
 
@@ -48,6 +48,11 @@ output "cluster_oidc_issuer_url" {
   value       = flatten(concat(aws_eks_cluster.this[*].identity[*].oidc.0.issuer, [""]))[0]
 }
 
+output "cluster_primary_security_group_id" {
+  description = "The cluster primary security group ID created by the EKS cluster on 1.14 or later. Referred to as 'Cluster security group' in the EKS console."
+  value       = var.cluster_version >= 1.14 ? element(concat(aws_eks_cluster.this[*].vpc_config[0].cluster_security_group_id, list("")), 0) : null
+}
+
 output "cloudwatch_log_group_name" {
   description = "Name of cloudwatch log group created"
   value       = aws_cloudwatch_log_group.this[*].name