[feature] New landing_zone for networking using hub spoke with Azure Virtual WAN

[arnaudlh]

Proposal

Create a model for Azure to deploy a regional hub and spoke model using Azure Virtual WAN using architecture as described here: https://docs.microsoft.com/en-us/azure/virtual-wan/virtual-wan-about.

This landing zone should allow you to easily create a Virtual WAN (Standard SKU) environment as well as flexible structure to onboard new HUB iteratively with its associated features:

• Azure Firewall
• Site to Site Gateway
• Point to Site Gateway
• Express Route Gateway
• Peering Virtual Network to the region hub
• Inter-hub and VNet-to-VNet transiting through the virtual hub

Pseudo code

Pseudo code for variable structure:

virtual_hub_config = {
  virtual_wan = {
    resource_group_name = "virtualwan-ns"
    name                = "ContosovWAN"
    dns_name            = "private.contoso.com"

    hubs = {
      hub1 = {
        hub_name           = "SEA-HUB"
        region             = "southeastasia"
        hub_address_prefix = "10.0.3.0/24"
        deploy_firewall    = true
        firewall_name      = "azfwvhub-sea"
        peerings = {     
          spoke1 = {
            hub_to_vitual_network_traffic_allowed          = true
            vitual_network_to_hub_gateways_traffic_allowed = true
            internet_security_enabled                      = false
          }
        }

        deploy_p2s = true
        p2s_config = { #config details }
        deploy_s2s = false
        s2s_config = { #config details }
        deploy_er  = false
        er_config  = { #config details }

Provisionning a new hub done with declaring another hub structure in the hubs object.

[arnaudlh]

Linking to https://github.com/Azure/caf-terraform-landingzones/tree/hub_mesh