Merge pull request #208 from kbst/eksvpcrefactor

EKS: Allow custom CIDRs for the VPC and its per AZ default subnets
kbst · Aug 23, 2021 · b070825 · b070825
2 parents b6c35ce + b9d29d2
commit b070825
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Showing 4 changed files with 23 additions and 7 deletions.
diff --git a/aws/_modules/eks/variables.tf b/aws/_modules/eks/variables.tf
@@ -18,6 +18,16 @@ variable "availability_zones" {
   type        = list(string)
 }
 
+variable "vpc_cidr" {
+  description = "CIDR to use for the VPC."
+  type        = string
+}
+
+variable "vpc_subnet_newbits" {
+  description = "CIDR to use for the VPC."
+  type        = string
+}
+
 variable "instance_type" {
   description = "AWS instance type to use for worker nodes."
   type        = string

diff --git a/aws/_modules/eks/vpc.tf b/aws/_modules/eks/vpc.tf
@@ -1,5 +1,5 @@
 resource "aws_vpc" "current" {
-  cidr_block = "10.0.0.0/16"
+  cidr_block = var.vpc_cidr
 
   tags = local.eks_metadata_tags
 }
@@ -8,7 +8,7 @@ resource "aws_subnet" "current" {
   count = length(var.availability_zones)
 
   availability_zone       = var.availability_zones[count.index]
-  cidr_block              = "10.0.${count.index}.0/24"
+  cidr_block              = cidrsubnet(aws_vpc.current.cidr_block, var.vpc_subnet_newbits, count.index)
   vpc_id                  = aws_vpc.current.id
   map_public_ip_on_launch = true
 

diff --git a/aws/cluster/configuration.tf b/aws/cluster/configuration.tf
@@ -16,6 +16,9 @@ locals {
   cluster_availability_zones_lookup = lookup(local.cfg, "cluster_availability_zones", "")
   cluster_availability_zones        = split(",", local.cluster_availability_zones_lookup)
 
+  cluster_vpc_cidr           = lookup(local.cfg, "cluster_vpc_cidr", "10.0.0.0/16")
+  cluster_vpc_subnet_newbits = lookup(local.cfg, "cluster_vpc_subnet_newbits", "8")
+
   cluster_instance_type = local.cfg["cluster_instance_type"]
 
   cluster_desired_capacity = local.cfg["cluster_desired_capacity"]

diff --git a/aws/cluster/main.tf b/aws/cluster/main.tf
@@ -19,11 +19,14 @@ module "cluster" {
   metadata_labels = module.cluster_metadata.labels
 
   availability_zones = local.cluster_availability_zones
-  instance_type      = local.cluster_instance_type
-  desired_capacity   = local.cluster_desired_capacity
-  max_size           = local.cluster_max_size
-  min_size           = local.cluster_min_size
-  cluster_version    = local.cluster_version
+  vpc_cidr           = local.cluster_vpc_cidr
+  vpc_subnet_newbits = local.cluster_vpc_subnet_newbits
+
+  instance_type    = local.cluster_instance_type
+  desired_capacity = local.cluster_desired_capacity
+  max_size         = local.cluster_max_size
+  min_size         = local.cluster_min_size
+  cluster_version  = local.cluster_version
 
   root_device_encrypted   = local.worker_root_device_encrypted
   root_device_volume_size = local.worker_root_device_volume_size