Feature: allow the use of private networks

README.md

@@ -993,6 +993,30 @@ enable_delete_protection = {
 ```
 
 </details>
+<details>
+
+<summary>Use only private ips in your cluster</summary>
+
+To use only private ips on your cluster, you need in your project:
+1. A network already configured.
+2. A machine with a public IP, with nat configured (see [Hetzner guide](https://community.hetzner.com/tutorials/how-to-set-up-nat-for-cloud-networks)).
+3. Access to your network (you can use wireguard, see [Hetnzer guide](https://docs.hetzner.com/cloud/apps/list/wireguard/)).
+4. A route in your network, destination: `0.0.0.0/0` through the private ip of your machine with NAT.
+5. Make sure the connexion to your vpn is established before launching terraform.
+
+Recommended values:
+- Network range: `10.0.0.0/8`
+- Subnet for your wireguard and NAT machine: `10.128.0.0/16`
+
+If you follow this values, in your kube.tf, please set:
+- `existing_network_id = [YOURID]` (with the brackets)
+- `network_ipv4_cidr = "10.0.0.0/9"`
+- Add `disable_ipv4 = true` and  `disable_ipv6 = true` in all machines in all nodepools (control planes + agents).
+
+This setup is compatible with a loadbalancer for your control planes, however you should consider to set
+`control_plane_lb_enable_public_interface = false` to keep ip private.
+</details>
+
 
 ## Debugging
 

agents.tf

@@ -29,6 +29,9 @@ module "agents" {
   swap_size                    = each.value.swap_size
   zram_size                    = each.value.zram_size
   keep_disk_size               = var.keep_disk_agents
+  disable_ipv4                 = each.value.disable_ipv4
+  disable_ipv6                 = each.value.disable_ipv6
+  network_id                   = length(var.existing_network_id) > 0 ? var.existing_network_id[0] : 0
 
   private_ipv4 = cidrhost(hcloud_network_subnet.agent[[for i, v in var.agent_nodepools : i if v.name == each.value.nodepool_name][0]].ip_range, each.value.index + 101)
 
@@ -57,6 +60,14 @@ locals {
     var.agent_nodes_custom_config,
     (v.selinux == true ? { selinux = true } : {})
   ) }
+
+  agent_ips = {
+    for k, v in module.agents : k => coalesce(
+      v.ipv4_address,
+      v.ipv6_address,
+      v.private_ipv4_address
+    )
+  }
 }
 
 resource "null_resource" "agent_config" {
@@ -71,7 +82,7 @@ resource "null_resource" "agent_config" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.agents[each.key].ipv4_address
+    host           = local.agent_ips[each.key]
     port           = var.ssh_port
   }
 
@@ -97,7 +108,7 @@ resource "null_resource" "agents" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.agents[each.key].ipv4_address
+    host           = local.agent_ips[each.key]
     port           = var.ssh_port
   }
 
@@ -166,7 +177,7 @@ resource "null_resource" "configure_longhorn_volume" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.agents[each.key].ipv4_address
+    host           = local.agent_ips[each.key]
     port           = var.ssh_port
   }
 
@@ -215,7 +226,7 @@ resource "null_resource" "configure_floating_ip" {
       NM_CONNECTION=$(nmcli -g GENERAL.CONNECTION device show eth0)
       nmcli connection modify "$NM_CONNECTION" \
         ipv4.method manual \
-        ipv4.addresses ${hcloud_floating_ip.agents[each.key].ip_address}/32,${module.agents[each.key].ipv4_address}/32 gw4 172.31.1.1 \
+        ipv4.addresses ${hcloud_floating_ip.agents[each.key].ip_address}/32,${local.agent_ips[each.key]}/32 gw4 172.31.1.1 \
         ipv4.route-metric 100 \
       && nmcli connection up "$NM_CONNECTION"
       EOT
@@ -226,7 +237,7 @@ resource "null_resource" "configure_floating_ip" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.agents[each.key].ipv4_address
+    host           = local.agent_ips[each.key]
     port           = var.ssh_port
   }
 

autoscaler-agents.tf

@@ -62,7 +62,7 @@ resource "null_resource" "configure_autoscaler" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.control_planes[keys(module.control_planes)[0]].ipv4_address
+    host           = coalesce(module.control_planes[keys(module.control_planes)[0]].ipv4_address, module.control_planes[keys(module.control_planes)[0]].ipv6_address, module.control_planes[keys(module.control_planes)[0]].private_ipv4_address)
     port           = var.ssh_port
   }
 
@@ -165,7 +165,7 @@ resource "null_resource" "autoscaled_nodes_registries" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = each.value.ipv4_address
+    host           = coalesce(each.value.ipv4_address, each.value.ipv6_address, one(each.value.network).ip)
     port           = var.ssh_port
   }
 

control_planes.tf

@@ -29,6 +29,9 @@ module "control_planes" {
   swap_size                    = each.value.swap_size
   zram_size                    = each.value.zram_size
   keep_disk_size               = var.keep_disk_cp
+  disable_ipv4                 = each.value.disable_ipv4
+  disable_ipv6                 = each.value.disable_ipv6
+  network_id                   = length(var.existing_network_id) > 0 ? var.existing_network_id[0] : 0
 
   # 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.
@@ -83,6 +86,14 @@ resource "hcloud_load_balancer_service" "control_plane" {
 }
 
 locals {
+  control_plane_ips = {
+    for k, v in module.control_planes : k => coalesce(
+      v.ipv4_address,
+      v.ipv6_address,
+      v.private_ipv4_address
+    )
+  }
+
   k3s-config = { for k, v in local.control_plane_nodes : k => merge(
     {
       node-name = module.control_planes[k].name
@@ -134,7 +145,7 @@ resource "null_resource" "control_plane_config" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.control_planes[each.key].ipv4_address
+    host           = local.control_plane_ips[each.key]
     port           = var.ssh_port
   }
 
@@ -167,7 +178,7 @@ resource "null_resource" "authentication_config" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.control_planes[each.key].ipv4_address
+    host           = local.control_plane_ips[each.key]
     port           = var.ssh_port
   }
 
@@ -197,7 +208,7 @@ resource "null_resource" "control_planes" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.control_planes[each.key].ipv4_address
+    host           = local.control_plane_ips[each.key]
     port           = var.ssh_port
   }
 

init.tf

@@ -19,13 +19,37 @@ resource "hcloud_load_balancer" "cluster" {
   }
 }
 
+resource "hcloud_load_balancer_network" "cluster" {
+  count = local.has_external_load_balancer ? 0 : 1
+
+  load_balancer_id        = hcloud_load_balancer.cluster.*.id[0]
+  subnet_id               = hcloud_network_subnet.agent.*.id[0]
+}
+
+resource "hcloud_load_balancer_target" "cluster" {
+  count = local.has_external_load_balancer ? 0 : 1
+
+  depends_on       = [hcloud_load_balancer_network.cluster]
+  type             = "label_selector"
+  load_balancer_id = hcloud_load_balancer.cluster.*.id[0]
+  label_selector   = join(",", [for k, v in merge(local.labels, local.labels_control_plane_node, local.labels_agent_node) : "${k}=${v}"])
+  use_private_ip   = true
+}
+
+locals {
+  first_control_plane_ip =  coalesce(
+    module.control_planes[keys(module.control_planes)[0]].ipv4_address,
+    module.control_planes[keys(module.control_planes)[0]].ipv6_address,
+    module.control_planes[keys(module.control_planes)[0]].private_ipv4_address
+  )
+}
 
 resource "null_resource" "first_control_plane" {
   connection {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.control_planes[keys(module.control_planes)[0]].ipv4_address
+    host           = local.first_control_plane_ip
     port           = var.ssh_port
   }
 
@@ -55,7 +79,7 @@ resource "null_resource" "first_control_plane" {
         var.use_control_plane_lb ? {
           tls-san = concat([hcloud_load_balancer.control_plane.*.ipv4[0], hcloud_load_balancer_network.control_plane.*.ip[0]], var.additional_tls_sans)
           } : {
-          tls-san = concat([module.control_planes[keys(module.control_planes)[0]].ipv4_address], var.additional_tls_sans)
+          tls-san = concat([local.first_control_plane_ip], var.additional_tls_sans)
         },
         local.etcd_s3_snapshots,
         var.control_planes_custom_config,
@@ -149,7 +173,7 @@ resource "null_resource" "kustomization" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.control_planes[keys(module.control_planes)[0]].ipv4_address
+    host           = local.first_control_plane_ip
     port           = var.ssh_port
   }
 

kube.tf.example

@@ -136,6 +136,10 @@ module "kube-hetzner" {
 
       # Enable automatic backups via Hetzner (default: false)
       # backups = true
+
+      # To disable public ips (default: false)
+      # disable_ipv4 = true
+      # disable_ipv6 = true
     },
     {
       name        = "control-plane-nbg1",
@@ -150,6 +154,10 @@ module "kube-hetzner" {
 
       # Enable automatic backups via Hetzner (default: false)
       # backups = true
+
+      # To disable public ips (default: false)
+      # disable_ipv4 = true
+      # disable_ipv6 = true
     },
     {
       name        = "control-plane-hel1",
@@ -164,6 +172,10 @@ module "kube-hetzner" {
 
       # Enable automatic backups via Hetzner (default: false)
       # backups = true
+
+      # To disable public ips (default: false)
+      # disable_ipv4 = true
+      # disable_ipv6 = true
     }
   ]
 

kubeconfig.tf

@@ -1,6 +1,6 @@
 data "remote_file" "kubeconfig" {
   conn {
-    host        = module.control_planes[keys(module.control_planes)[0]].ipv4_address
+    host        = local.first_control_plane_ip
     port        = var.ssh_port
     user        = "root"
     private_key = var.ssh_private_key
@@ -13,7 +13,7 @@ data "remote_file" "kubeconfig" {
 
 locals {
   kubeconfig_server_address = var.kubeconfig_server_address != "" ? var.kubeconfig_server_address : (var.use_control_plane_lb ? hcloud_load_balancer.control_plane.*.ipv4[0] : (
-    can(module.control_planes[keys(module.control_planes)[0]].ipv4_address) ? module.control_planes[keys(module.control_planes)[0]].ipv4_address : "unknown"
+    can(local.first_control_plane_ip) ? local.first_control_plane_ip : "unknown"
   ))
   kubeconfig_external = replace(replace(data.remote_file.kubeconfig.content, "127.0.0.1", local.kubeconfig_server_address), "default", var.cluster_name)
   kubeconfig_parsed   = yamldecode(local.kubeconfig_external)

kustomization_user.tf

@@ -9,7 +9,7 @@ resource "null_resource" "kustomization_user" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.control_planes[keys(module.control_planes)[0]].ipv4_address
+    host           = local.first_control_plane_ip
     port           = var.ssh_port
   }
 
@@ -40,7 +40,7 @@ resource "null_resource" "kustomization_user_deploy" {
     user           = "root"
     private_key    = var.ssh_private_key
     agent_identity = local.ssh_agent_identity
-    host           = module.control_planes[keys(module.control_planes)[0]].ipv4_address
+    host           = local.first_control_plane_ip
     port           = var.ssh_port
   }
 

locals.tf

@@ -143,7 +143,10 @@ locals {
         index : node_index
         selinux : nodepool_obj.selinux
         placement_group_compat_idx : nodepool_obj.placement_group_compat_idx,
-        placement_group : nodepool_obj.placement_group
+        placement_group : nodepool_obj.placement_group,
+        disable_ipv4: nodepool_obj.disable_ipv4,
+        disable_ipv6: nodepool_obj.disable_ipv6,
+        network_id: nodepool_obj.network_id,
       }
     }
   ]...)
@@ -167,7 +170,10 @@ locals {
         index : node_index
         selinux : nodepool_obj.selinux
         placement_group_compat_idx : nodepool_obj.placement_group_compat_idx,
-        placement_group : nodepool_obj.placement_group
+        placement_group : nodepool_obj.placement_group,
+        disable_ipv4: nodepool_obj.disable_ipv4,
+        disable_ipv6: nodepool_obj.disable_ipv6,
+        network_id: nodepool_obj.network_id,
       }
     }
   ]...)
@@ -193,6 +199,9 @@ locals {
           placement_group_compat_idx : nodepool_obj.placement_group_compat_idx,
           placement_group : nodepool_obj.placement_group,
           index : floor(tonumber(node_key)),
+          disable_ipv4: nodepool_obj.disable_ipv4,
+          disable_ipv6: nodepool_obj.disable_ipv6,
+          network_id: nodepool_obj.network_id,
         },
         { for key, value in node_obj : key => value if value != null },
         {
@@ -835,8 +844,9 @@ cloudinit_write_files_common = <<EOT
     set -euo pipefail
 
     sleep 11
-
-    INTERFACE=$(ip link show | awk '/^3:/{print $2}' | sed 's/://g')
+
+    # Take row beginning with 3 if exists, 2 otherwise (if only a private ip)
+    INTERFACE=$(ip link show | awk 'BEGIN{l3=""}; /^3:/{l3=$2}; /^2:/{l2=$2}; END{if(l3!="") print l3; else print l2}' | sed 's/://g')
     MAC=$(cat /sys/class/net/$INTERFACE/address)
 
     cat <<EOF > /etc/udev/rules.d/70-persistent-net.rules
@@ -846,11 +856,14 @@ cloudinit_write_files_common = <<EOT
     ip link set $INTERFACE down
     ip link set $INTERFACE name eth1
     ip link set eth1 up
-
-    eth0_connection=$(nmcli -g GENERAL.CONNECTION device show eth0)
-    nmcli connection modify "$eth0_connection" \
-      con-name eth0 \
-      connection.interface-name eth0
+
+    # In case of a private only network, eth0 does not exists
+    if ip link show eth0 &>/dev/null; then
+        eth0_connection=$(nmcli -g GENERAL.CONNECTION device show eth0)
+        nmcli connection modify "$eth0_connection" \
+          con-name eth0 \
+          connection.interface-name eth0
+    fi
 
     eth1_connection=$(nmcli -g GENERAL.CONNECTION device show eth1)
     nmcli connection modify "$eth1_connection" \