automated the creation of the subnets

agents.tf

@@ -12,11 +12,11 @@ module "agents" {
   placement_group_id     = hcloud_placement_group.k3s.id
   location               = var.location
   server_type            = each.value.server_type
-  ipv4_subnet_id         = hcloud_network_subnet.subnet[each.value.subnet].id
+  ipv4_subnet_id         = hcloud_network_subnet.subnet[index(keys(var.agent_nodepools), each.value.nodepool_name) + 2].id
 
   # We leave some room so 100 eventual Hetzner LBs that can be created perfectly safely
   # It leaves the subnet with 254 x 254 - 100 = 64416 IPs to use, so probably enough.
-  private_ipv4 = cidrhost(var.network_ipv4_subnets[each.value.subnet], each.value.index + 101)
+  private_ipv4 = cidrhost(local.network_ipv4_subnets[index(keys(var.agent_nodepools), each.value.nodepool_name) + 2], each.value.index + 101)
 
   labels = {
     "provisioner" = "terraform",

control_planes.tf

@@ -11,11 +11,11 @@ module "control_planes" {
   placement_group_id     = hcloud_placement_group.k3s.id
   location               = var.location
   server_type            = var.control_plane_server_type
-  ipv4_subnet_id         = hcloud_network_subnet.subnet["control_plane"].id
+  ipv4_subnet_id         = hcloud_network_subnet.subnet[1].id
 
   # We leave some room so 100 eventual Hetzner LBs that can be created perfectly safely
   # It leaves the subnet with 254 x 254 - 100 = 64416 IPs to use, so probably enough.  
-  private_ipv4 = cidrhost(var.network_ipv4_subnets["control_plane"], count.index + 101)
+  private_ipv4 = cidrhost(local.network_ipv4_subnets[1], count.index + 101)
 
   labels = {
     "provisioner" = "terraform",

locals.tf

@@ -23,7 +23,7 @@ locals {
   hetzner_cloud_api_ipv4        = "213.239.246.1/32"
 
   whitelisted_ips = [
-    var.network_ipv4_range,
+    local.network_ipv4_cidr,
     local.hetzner_metadata_service_ipv4,
     local.hetzner_cloud_api_ipv4,
     "127.0.0.1/32",
@@ -175,9 +175,15 @@ locals {
       format("%s-%s", nodepool_name, index) => {
         nodepool_name : nodepool_name,
         server_type : nodepool_obj.server_type,
-        subnet : nodepool_obj.subnet,
         index : index
       }
     }
   ]...)
+
+  # The main network cidr that all subnets will be created upon
+  network_ipv4_cidr = "10.0.0.0/8"
+
+  # The first two subnets are respectively the default subnet 10.0.0.0/16 use for potientially anything and 10.1.0.0/16 used for control plane nodes.
+  # the rest of the subnets are for agent nodes in each nodepools.
+  network_ipv4_subnets = [for index in range(length(var.agent_nodepools) + 2) : cidrsubnet(local.network_ipv4_cidr, 8, index)]
 }

main.tf

@@ -15,25 +15,15 @@ resource "hcloud_ssh_key" "k3s" {
 
 resource "hcloud_network" "k3s" {
   name     = random_pet.cluster.id
-  ip_range = var.network_ipv4_range
+  ip_range = local.network_ipv4_cidr
-}
-
-# This is the default subnet to be used by the load balancer.
-resource "hcloud_network_subnet" "default" {
-  network_id   = hcloud_network.k3s.id
-  type         = "cloud"
-  network_zone = var.network_region
-  ip_range     = "10.0.0.0/16"
 }
 
 resource "hcloud_network_subnet" "subnet" {
-  for_each     = var.network_ipv4_subnets
+  count        = length(local.network_ipv4_subnets)
   network_id   = hcloud_network.k3s.id
   type         = "cloud"
   network_zone = var.network_region
-  ip_range     = each.value
+  ip_range     = local.network_ipv4_subnets[count.index]
-
-  depends_on = [hcloud_network_subnet.default]
 }
 
 resource "hcloud_firewall" "k3s" {

terraform.tfvars.example

@@ -18,15 +18,6 @@ private_key  = "/home/username/.ssh/id_ed25519"
 location         = "fsn1"       # change to `ash` for us-east Ashburn, Virginia location
 network_region   = "eu-central" # change to `us-east` if location is ash
 
-# You can have up to as many subnets as you want (preferably if the form of 10.X.0.0/16),
-# their primary use is to logically separate the nodes.
-# The control_plane network is mandatory.
-network_ipv4_subnets = {
-  control_plane = "10.1.0.0/16"
-  agent_big     = "10.2.0.0/16"
-  agent_small   = "10.3.0.0/16"
-}
-
 # At least 3 server nodes is recommended for HA, otherwise you need to turn off automatic upgrade (see ReadMe).
 # As per rancher docs, it must be always an odd number, never even! See https://rancher.com/docs/k3s/latest/en/installation/ha-embedded/
 # For instance, 1 is ok (non-HA), 2 not ok, 3 is ok (becomes HA).
@@ -56,9 +47,6 @@ load_balancer_type        = "lb11"
 
 ### The following values are fully optional
 
-# It's best to leave the network range as is, unless you know what you are doing. The default is "10.0.0.0/8".
-# network_ipv4_range = "10.0.0.0/8"
-
 # If you want to use a specific Hetzner CCM and CSI version, set them below, otherwise leave as is for the latest versions
 # hetzner_ccm_version = ""
 # hetzner_csi_version = ""

variables.tf

@@ -30,17 +30,6 @@ variable "network_region" {
   type        = string
 }
 
-variable "network_ipv4_range" {
-  description = "Default IPv4 range for network"
-  type        = string
-  default     = "10.0.0.0/8"
-}
-
-variable "network_ipv4_subnets" {
-  description = "Subnets definition for default network"
-  type        = map(string)
-}
-
 variable "control_plane_server_type" {
   description = "Default control plane server type"
   type        = string