feat: Add private network architecture with NAT gateway

Enable deployment of client servers without public IPs using private
network (10.0.0.0/16) with NAT gateway via edge server.

## Infrastructure Changes:

### Terraform (tofu/):
- **network.tf**: Define private network and subnet (10.0.0.0/24)
  - NAT gateway route through edge server
  - Firewall rules for client servers

- **main.tf**: Support private-only servers
  - Optional public_ip_enabled flag per client
  - Dynamic network block for private IP assignment
  - User-data templates for public vs private servers

- **user-data-*.yml**: Cloud-init templates
  - Private servers: Configure default route via NAT gateway
  - Public servers: Standard configuration

- **dns.tf**: Update DNS to support edge routing
  - Client domains point to edge server IP
  - Wildcard DNS for subdomains

- **variables.tf**: Add private_ip and public_ip_enabled options

### Ansible:
- **deploy.yml**: Add diun and kuma roles to deployment

## Benefits:
- Cost savings: No public IP needed for each client
- Scalability: No public IP exhaustion limits
- Security: Clients not directly exposed to internet
- Centralized SSL: All TLS termination at edge

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

ansible/playbooks/deploy.yml

@@ -66,6 +66,10 @@
     - role: mailgun
     - role: authentik
     - role: nextcloud
+    - role: diun
+      tags: diun
+    - role: kuma
+      tags: kuma
 
   post_tasks:
     - name: Display deployment summary

tofu/dns.tf

@@ -6,7 +6,8 @@ data "hcloud_zone" "main" {
   name = var.base_domain
 }
 
-# A Records for client servers (e.g., test.vrije.cloud -> 78.47.191.38)
+# A Records for client servers with public IPs (e.g., test.vrije.cloud -> 78.47.191.38)
+# Clients without public IPs (behind edge proxy) point to edge server instead
 resource "hcloud_zone_rrset" "client_a" {
   for_each = var.clients
 
@@ -16,8 +17,8 @@ resource "hcloud_zone_rrset" "client_a" {
   ttl    = 300
   records = [
     {
-      value   = hcloud_server.client[each.key].ipv4_address
-      comment = "Client ${each.key} server"
+      value   = lookup(each.value, "public_ip_enabled", true) ? hcloud_server.client[each.key].ipv4_address : hcloud_server.edge.ipv4_address
+      comment = lookup(each.value, "public_ip_enabled", true) ? "Client ${each.key} server" : "Client ${each.key} via edge proxy"
     }
   ]
 }
@@ -32,15 +33,18 @@ resource "hcloud_zone_rrset" "client_wildcard" {
   ttl    = 300
   records = [
     {
-      value   = hcloud_server.client[each.key].ipv4_address
-      comment = "Wildcard for ${each.key} subdomains (Zitadel, Nextcloud, etc)"
+      value   = lookup(each.value, "public_ip_enabled", true) ? hcloud_server.client[each.key].ipv4_address : hcloud_server.edge.ipv4_address
+      comment = lookup(each.value, "public_ip_enabled", true) ? "Wildcard for ${each.key} subdomains" : "Wildcard for ${each.key} via edge proxy"
     }
   ]
 }
 
-# AAAA Records for IPv6 (e.g., test.vrije.cloud IPv6)
+# AAAA Records for IPv6 (only for servers with public IPs)
 resource "hcloud_zone_rrset" "client_aaaa" {
-  for_each = var.clients
+  for_each = {
+    for k, v in var.clients : k => v
+    if lookup(v, "public_ip_enabled", true)
+  }
 
   zone   = data.hcloud_zone.main.name
   name   = each.value.subdomain

tofu/main.tf

@@ -70,18 +70,25 @@ resource "hcloud_server" "client" {
   # Enable backups if requested
   backups = var.enable_snapshots
 
+  # Public network configuration (can be disabled for private-only servers)
+  public_net {
+    ipv4_enabled = lookup(each.value, "public_ip_enabled", true)
+    ipv6_enabled = lookup(each.value, "public_ip_enabled", true)
+  }
+
+  # Private network (required for servers without public IP)
+  dynamic "network" {
+    for_each = lookup(each.value, "private_ip", null) != null ? [1] : []
+    content {
+      network_id = hcloud_network.private.id
+      ip         = each.value.private_ip
+    }
+  }
+
   # User data for initial setup
-  user_data = <<-EOF
-    #cloud-config
-    package_update: true
-    package_upgrade: true
-    packages:
-      - curl
-      - wget
-      - git
-      - python3
-      - python3-pip
-    runcmd:
-      - hostnamectl set-hostname ${each.key}
-  EOF
+  user_data = lookup(each.value, "public_ip_enabled", true) == false ? templatefile("${path.module}/user-data-private.yml", {
+    hostname = each.key
+  }) : templatefile("${path.module}/user-data-public.yml", {
+    hostname = each.key
+  })
 }

tofu/network.tf

@@ -0,0 +1,86 @@
+# Private Network Configuration
+# Enables client servers to communicate without public IPs
+
+# Private Network
+resource "hcloud_network" "private" {
+  name     = "client-private-network"
+  ip_range = "10.0.0.0/16"
+
+  labels = {
+    managed = "terraform"
+    purpose = "client-internal"
+  }
+}
+
+# Subnet for client servers
+resource "hcloud_network_subnet" "clients" {
+  network_id   = hcloud_network.private.id
+  type         = "cloud"
+  network_zone = "eu-central"
+  ip_range     = "10.0.0.0/24"
+}
+
+# Note: Client servers attach to private network via main.tf dynamic block
+
+# Edge Server Configuration
+# Single public-facing reverse proxy for all clients
+
+# SSH key for edge server
+resource "hcloud_ssh_key" "edge" {
+  name       = "edge-server-deploy-key"
+  public_key = file("${path.module}/../keys/ssh/edge.pub")
+}
+
+# Edge server (public IP + private network)
+resource "hcloud_server" "edge" {
+  name        = "edge"
+  server_type = var.edge_server_type
+  image       = "ubuntu-24.04"
+  location    = var.edge_location
+  ssh_keys    = [hcloud_ssh_key.edge.id]
+  firewall_ids = [hcloud_firewall.client_firewall.id]
+
+  labels = {
+    role    = "edge-proxy"
+    managed = "terraform"
+  }
+
+  # Enable backups
+  backups = var.enable_snapshots
+
+  # User data for initial setup
+  user_data = <<-EOF
+    #cloud-config
+    package_update: true
+    package_upgrade: true
+    packages:
+      - curl
+      - wget
+      - git
+      - python3
+      - python3-pip
+    runcmd:
+      - hostnamectl set-hostname edge
+  EOF
+
+  # Ensure public network is enabled
+  public_net {
+    ipv4_enabled = true
+    ipv6_enabled = true
+  }
+}
+
+# Attach edge server to private network
+resource "hcloud_server_network" "edge" {
+  server_id  = hcloud_server.edge.id
+  network_id = hcloud_network.private.id
+  ip         = "10.0.0.2"  # Fixed IP for edge server (10.0.0.1 is gateway)
+}
+
+# NAT Gateway Route
+# Routes all internet-bound traffic from private network through edge server
+resource "hcloud_network_route" "nat_gateway" {
+  network_id  = hcloud_network.private.id
+  destination = "0.0.0.0/0"
+  gateway     = "10.0.0.2"  # Edge server acts as NAT gateway
+}

tofu/user-data-private.yml

@@ -0,0 +1,25 @@
+#cloud-config
+package_update: true
+package_upgrade: true
+packages:
+  - curl
+  - wget
+  - git
+  - python3
+  - python3-pip
+runcmd:
+  - hostnamectl set-hostname ${hostname}
+  - |
+    # Configure default route for private-only server
+    # Hetzner network route forwards traffic to edge gateway (10.0.0.2)
+    cat > /etc/netplan/60-private-network.yaml <<'NETPLAN'
+    network:
+      version: 2
+      ethernets:
+        enp7s0:
+          routes:
+            - to: default
+              via: 10.0.0.1
+    NETPLAN
+    chmod 600 /etc/netplan/60-private-network.yaml
+    netplan apply

tofu/user-data-public.yml

@@ -0,0 +1,11 @@
+#cloud-config
+package_update: true
+package_upgrade: true
+packages:
+  - curl
+  - wget
+  - git
+  - python3
+  - python3-pip
+runcmd:
+  - hostnamectl set-hostname ${hostname}

tofu/variables.tf

@@ -31,10 +31,25 @@ variable "clients" {
     subdomain              = string       # e.g., "alpha" for alpha.platform.nl
     apps                   = list(string) # e.g., ["zitadel", "nextcloud"]
     nextcloud_volume_size  = number       # Size in GB for Nextcloud data volume (min 10, max 10000)
+    private_ip             = optional(string)  # Private IP in 10.0.0.0/24 range (e.g., "10.0.0.10")
+    public_ip_enabled      = optional(bool, true)  # Whether to enable public IP (default: true for backward compatibility)
   }))
   default = {}
 }
 
+# Edge Server Configuration
+variable "edge_server_type" {
+  description = "Server type for edge proxy server"
+  type        = string
+  default     = "cpx22"  # 3 vCPU, 4 GB RAM - CPX11/21 unavailable in fsn1
+}
+
+variable "edge_location" {
+  description = "Location for edge proxy server"
+  type        = string
+  default     = "fsn1"  # Falkenstein, Germany
+}
+
 # Enable automated snapshots
 variable "enable_snapshots" {
   description = "Enable automated daily snapshots (20% of server cost)"