feat: Allow communication between pods on workers and pods using the primary cluster security group (optional) (#892)

NOTES: New variable `worker_create_cluster_primary_security_group_rules` to allow communication between pods on workers and pods using the primary cluster security group (Managed Node Groups or Fargate). It defaults to `false` to avoid potential conflicts with existing security group rules users may have implemented.

README.md

@@ -200,6 +200,7 @@ MIT Licensed. See [LICENSE](https://github.com/terraform-aws-modules/terraform-a
 | worker\_ami\_name\_filter\_windows | Name filter for AWS EKS Windows worker AMI. If not provided, the latest official AMI for the specified 'cluster\_version' is used. | `string` | `""` | no |
 | worker\_ami\_owner\_id | The ID of the owner for the AMI to use for the AWS EKS workers. Valid values are an AWS account ID, 'self' (the current account), or an AWS owner alias (e.g. 'amazon', 'aws-marketplace', 'microsoft'). | `string` | `"602401143452"` | no |
 | worker\_ami\_owner\_id\_windows | The ID of the owner for the AMI to use for the AWS EKS Windows workers. Valid values are an AWS account ID, 'self' (the current account), or an AWS owner alias (e.g. 'amazon', 'aws-marketplace', 'microsoft'). | `string` | `"801119661308"` | no |
+| worker\_create\_cluster\_primary\_security\_group\_rules | Whether to create security group rules to allow communication between pods on workers and pods using the primary cluster security group. | `bool` | `false` | no |
 | worker\_create\_initial\_lifecycle\_hooks | Whether to create initial lifecycle hooks provided in worker groups. | `bool` | `false` | no |
 | worker\_create\_security\_group | Whether to create a security group for the workers or attach the workers to `worker_security_group_id`. | `bool` | `true` | no |
 | worker\_groups | A list of maps defining worker group configurations to be defined using AWS Launch Configurations. See workers\_group\_defaults for valid keys. | `any` | `[]` | no |

local.tf

@@ -8,10 +8,11 @@ locals {
     )
   ]
 
-  cluster_security_group_id = var.cluster_create_security_group ? join("", aws_security_group.cluster.*.id) : var.cluster_security_group_id
-  cluster_iam_role_name     = var.manage_cluster_iam_resources ? join("", aws_iam_role.cluster.*.name) : var.cluster_iam_role_name
-  cluster_iam_role_arn      = var.manage_cluster_iam_resources ? join("", aws_iam_role.cluster.*.arn) : join("", data.aws_iam_role.custom_cluster_iam_role.*.arn)
-  worker_security_group_id  = var.worker_create_security_group ? join("", aws_security_group.workers.*.id) : var.worker_security_group_id
+  cluster_security_group_id         = var.cluster_create_security_group ? join("", aws_security_group.cluster.*.id) : var.cluster_security_group_id
+  cluster_primary_security_group_id = var.cluster_version >= 1.14 ? element(concat(aws_eks_cluster.this[*].vpc_config[0].cluster_security_group_id, list("")), 0) : null
+  cluster_iam_role_name             = var.manage_cluster_iam_resources ? join("", aws_iam_role.cluster.*.name) : var.cluster_iam_role_name
+  cluster_iam_role_arn              = var.manage_cluster_iam_resources ? join("", aws_iam_role.cluster.*.arn) : join("", data.aws_iam_role.custom_cluster_iam_role.*.arn)
+  worker_security_group_id          = var.worker_create_security_group ? join("", aws_security_group.workers.*.id) : var.worker_security_group_id
 
   default_iam_role_id    = concat(aws_iam_role.workers.*.id, [""])[0]
   default_ami_id_linux   = coalesce(local.workers_group_defaults.ami_id, data.aws_ami.eks_worker.id)

outputs.tf

@@ -53,7 +53,7 @@ output "cluster_oidc_issuer_url" {
 
 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
+  value       = local.cluster_primary_security_group_id
 }
 
 output "cloudwatch_log_group_name" {

variables.tf

@@ -228,6 +228,12 @@ variable "worker_create_initial_lifecycle_hooks" {
   default     = false
 }
 
+variable "worker_create_cluster_primary_security_group_rules" {
+  description = "Whether to create security group rules to allow communication between pods on workers and pods using the primary cluster security group."
+  type        = bool
+  default     = false
+}
+
 variable "permissions_boundary" {
   description = "If provided, all IAM roles will be created with this permissions boundary attached."
   type        = string

workers.tf

@@ -338,6 +338,28 @@ resource "aws_security_group_rule" "workers_ingress_cluster_https" {
   type                     = "ingress"
 }
 
+resource "aws_security_group_rule" "workers_ingress_cluster_primary" {
+  count                    = var.worker_create_security_group && var.worker_create_cluster_primary_security_group_rules && var.cluster_version >= 1.14 && var.create_eks ? 1 : 0
+  description              = "Allow pods running on workers to receive communication from cluster primary security group (e.g. Fargate pods)."
+  protocol                 = "all"
+  security_group_id        = local.worker_security_group_id
+  source_security_group_id = local.cluster_primary_security_group_id
+  from_port                = 0
+  to_port                  = 65535
+  type                     = "ingress"
+}
+
+resource "aws_security_group_rule" "cluster_primary_ingress_workers" {
+  count                    = var.worker_create_security_group && var.worker_create_cluster_primary_security_group_rules && var.cluster_version >= 1.14 && var.create_eks ? 1 : 0
+  description              = "Allow pods running on workers to send communication to cluster primary security group (e.g. Fargate pods)."
+  protocol                 = "all"
+  security_group_id        = local.cluster_primary_security_group_id
+  source_security_group_id = local.worker_security_group_id
+  from_port                = 0
+  to_port                  = 65535
+  type                     = "ingress"
+}
+
 resource "aws_iam_role" "workers" {
   count                 = var.manage_worker_iam_resources && var.create_eks ? 1 : 0
   name_prefix           = var.workers_role_name != "" ? null : aws_eks_cluster.this[0].name