hunfabric/examples/networking/hub-and-spoke-vpn

Hub and Spoke via VPN

This example creates a simple Hub and Spoke VPN setup, where the VPC network connects satellite locations (spokes) through a single intermediary location (hub) via IPsec HA VPN.

A few additional features are also shown:

• custom BGP advertisements to implement transitivity between spokes
• VPC Global Routing to leverage a regional set of VPN gateways in different regions as next hops (used here for illustrative/study purpose, not usually done in real life)

The example has been purposefully kept simple to show how to use and wire the VPC and VPN-HA modules together, and so that it can be used as a basis for experimentation. For a more complex scenario that better reflects real-life usage, including Shared VPC and DNS cross-project binding please refer to the FAST network stage.

This is the high level diagram of this example:

Managed resources and services

This sample creates several distinct groups of resources:

• one VPC for each hub and each spoke
• one set of firewall rules for each VPC
• one HA VPN gateway with two tunnels and one Cloud Router for each spoke
• two HA VPN gateways with two tunnels and a shared Cloud Routers for the hub
• one DNS private zone in the hub
• one DNS peering zone and one DNS private zone in each spoke
• one test instance for the hub each spoke

Prerequisites

A single pre-existing project is used in this example to keep variables and complexity to a minimum, in a real world scenarios each spoke would probably use a separate project.

The provided project needs a valid billing account, the Compute and DNS APIs are enabled by the example.

You can easily create such a project by commenting turning on project creation in the project module contained in main.tf, as shown in this snippet:

module "project" {
  source           = "../../..//modules/project"
  name             = var.project_id
  # comment or remove this line to enable project creation
  # project_create = false
  # add the following line with your billing account id value
  billing_account  = "12345-ABCD-12345"
  services = [
    "compute.googleapis.com",
    "dns.googleapis.com"
  ]
  service_config = {
    disable_on_destroy         = false
    disable_dependent_services = false
  }
}

Testing

Once the example is up, you can quickly test features by logging in to one of the test VMs:

gcloud compute ssh hs-ha-lnd-test-r1
# test DNS resolution of the landing zone
ping test-r1.example.com
# test DNS resolution of the prod zone, and prod reachability
ping test-r1.prod.example.com
# test DNS resolution of the dev zone, and dev reachability via global routing
ping test-r2.dev.example.com

Files

name	description	modules
main.tf	Module-level locals and resources.	compute-vm · project
net-dev.tf	Development spoke VPC.	dns · net-vpc · net-vpc-firewall
net-landing.tf	Landing hub VPC.	dns · net-vpc · net-vpc-firewall
net-prod.tf	Production spoke VPC.	dns · net-vpc · net-vpc-firewall
outputs.tf	Module outputs.
variables.tf	Module variables.
versions.tf	Version pins.
vpn-dev-r1.tf	Landing to Development VPN for region 1.	net-vpn-ha
vpn-prod-r1.tf	Landing to Production VPN for region 1.	net-vpn-ha

Variables

name	description	type	required	default
project_id	Project id for all resources.	string	✓
ip_ranges	Subnet IP CIDR ranges.	map(string)		{…}
ip_secondary_ranges	Subnet secondary ranges.	map(map(string))		{}
prefix	Prefix used in resource names.	string		null
project_create_config	Populate with billing account id to trigger project creation.	object({…})		null
regions	VPC regions.	map(string)		{…}
vpn_configs	VPN configurations.	map(object({…}))		{…}

Outputs

name	description	sensitive
subnets	Subnet details.
vms	GCE VMs.