VPN Gateway Configuration

Point-to-Site and Site-to-Site VPN connectivity for secure remote access to the private AKS cluster and Azure services.

NOTE

Part of the Deployment Guide. Return there for navigation and deployment order.

IMPORTANT

Required for default configuration. With should_enable_private_aks_cluster = true (the default), you must deploy this VPN Gateway and connect before running kubectl commands or cluster setup scripts. Without VPN, the private cluster endpoint is not accessible.

To skip VPN, set should_enable_private_aks_cluster = false in your terraform.tfvars for a public AKS control plane.

📋 Prerequisites

• Platform infrastructure deployed (cd infrastructure/terraform && terraform apply)
• Terraform 1.5+ installed
• Core variables matching parent deployment (environment, resource_prefix, location)

🚀 Quick Start

cd infrastructure/terraform/vpn

# Configure
cp terraform.tfvars.example terraform.tfvars
# Edit: environment, resource_prefix, location (must match 001-iac)

terraform init && terraform apply

Deployment takes 20-30 minutes for the VPN Gateway.

⚙️ Configuration

Variable	Description	Default
gateway_subnet_address_prefix	GatewaySubnet CIDR (min /27)	10.0.3.0/27
vpn_gateway_config.sku	Gateway SKU	VpnGw1AZ
vpn_gateway_config.client_address_pool	P2S client IP range	["192.168.200.0/24"]
aad_auth_config.should_enable	Enable Microsoft Entra ID auth	true
revoked_client_certificates	Public SHA-1 thumbprints for revoked client certificates	[]

Non-AZ VPN Gateway SKUs are being deprecated by Azure. Use the AZ equivalents (VpnGw1AZ, VpnGw2AZ, VpnGw3AZ) to avoid portal warnings and unplanned SKU updates outside Terraform.

🔐 Authentication Options

Microsoft Entra ID

Enabled by default for supported Azure VPN Client platforms.

aad_auth_config = {
  should_enable = true
}

Certificate

Use certificate authentication for Ubuntu strongSwan or environments without Microsoft Entra ID integration:

aad_auth_config = {
  should_enable = false
}
root_certificate_public_data = "MIIC5jCCAc6g..." # Base64-encoded cert

💻 VPN Client Setup

Select a Client

Platform	Client	Authentication
Windows	Azure VPN Client	Microsoft Entra ID or certificate
macOS	Azure VPN Client	Microsoft Entra ID or certificate
Ubuntu	strongSwan	Certificate with IKEv2

WARNING

Microsoft retires Azure VPN Client for Linux on August 31, 2026. Use strongSwan with certificate authentication for the supported Ubuntu edge path.

Download VPN Configuration

1. Open the Azure Portal
2. Navigate to your Virtual Network Gateway resource:
   • Search for "Virtual network gateways" in the portal search bar
   • Select the gateway matching your deployment (e.g., vgw-<resource_prefix>-<environment>-<instance>)
3. Select Point-to-site configuration from the left menu
4. Click Download VPN client button
5. Save and extract the downloaded ZIP file

Import Azure VPN Client Configuration

1. Open the Azure VPN Client application
2. Click the + (Import) button in the bottom left
3. Navigate to the extracted ZIP folder
4. Open the AzureVPN folder
5. Select azurevpnconfig_aad.xml (for Azure AD authentication)
6. Click Save

Connect with Azure VPN Client

1. Select the imported connection profile
2. Click Connect
3. Authenticate with your Azure AD credentials when prompted
4. Verify connection status shows "Connected"

Once connected, you can access private endpoints including OSMO UI, PostgreSQL, and Redis.

Configure Ubuntu strongSwan

The Ubuntu HiL journey uses VPN only when the approved endpoint requires private routing. Local host and K3s readiness remain independent of VPN.

Follow Optional Private Reachability. The request command generates the Ubuntu private key locally and publishes only the CSR. The response command retrieves and validates public material, then exits for private-only Key Vault restoration. A separate connection command installs strongSwan and preserves the Internet default route. The root CA private key remains on the external signing system.

Revoke a compromised leaf certificate by adding its public SHA-1 thumbprint:

revoked_client_certificates = [{
  name       = "hil-lab-01"
  thumbprint = "0123456789ABCDEF0123456789ABCDEF01234567"
}]

🏢 Site-to-Site VPN

Connect on-premises networks:

vpn_site_connections = [{
  name                 = "on-prem-datacenter"
  address_spaces       = ["10.100.0.0/16"]
  gateway_ip_address   = "203.0.113.10"
  shared_key_reference = "datacenter-key"
}]

vpn_site_shared_keys = {
  "datacenter-key" = "your-preshared-key"
}

🔗 Related

• Infrastructure Deployment — Main infrastructure documentation
• Private DNS — Private DNS for OSMO UI (requires VPN)

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