Set Azure subscription ID when applying Terraform files

Signed-off-by: Daniel Weiße <dw@edgeless.systems>

dev-docs/howto/vpn/on-prem-terraform/main.tf

@@ -13,6 +13,10 @@ terraform {
 
 provider "azurerm" {
   features {}
+  subscription_id = var.subscription_id
+  # This enables all resource providers.
+  # In the future, we might want to use `resource_providers_to_register` to registers just the ones we need.
+  resource_provider_registrations = "all"
 }
 
 locals {
@@ -103,7 +107,7 @@ resource "azurerm_route_table" "route_table" {
   name                          = "vpn-routes"
   location                      = azurerm_resource_group.rg.location
   resource_group_name           = azurerm_resource_group.rg.name
-  disable_bgp_route_propagation = false
+  bgp_route_propagation_enabled = false
 
   dynamic "route" {
     for_each = var.remote_ts

dev-docs/howto/vpn/on-prem-terraform/variables.tf

@@ -1,3 +1,9 @@
+variable "subscription_id" {
+  type        = string
+  description = "Azure subscription ID. This can also be sourced from the ARM_SUBSCRIPTION_ID environment variable: https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs#subscription_id"
+  default     = ""
+}
+
 variable "resource_group_location" {
   type        = string
   default     = "westeurope"