Add missing index html to cdn (#637)

Author: Krusty93

infra/resources/psn/prod/README.md

@@ -77,10 +77,12 @@ The diagram below shows the resources actually deployed. This is a work in progr
 | [azurerm_storage_account.cdn](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_account) | resource |
 | [azurerm_storage_account_static_website.cdn](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_account_static_website) | resource |
 | [azurerm_storage_blob.healthcheck](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_blob) | resource |
+| [azurerm_storage_blob.index](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_blob) | resource |
 | [azurerm_storage_container.exchange](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_container) | resource |
 | [azurerm_storage_container.hub_spid_login](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_container) | resource |
 | [azurerm_storage_container.pdnd](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_container) | resource |
 | [azurerm_storage_container.probes](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_container) | resource |
+| [azurerm_storage_container.root](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_container) | resource |
 | [azurerm_storage_container.well_known](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_container) | resource |
 | [azurerm_subnet.apim](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/subnet) | resource |
 | [azurerm_subnet_route_table_association.apim_apps](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/subnet_route_table_association) | resource |

infra/resources/psn/prod/cdn.tf

@@ -63,6 +63,12 @@ resource "azurerm_storage_container" "probes" {
   container_access_type = "container"
 }
 
+resource "azurerm_storage_container" "root" {
+  name                  = "$root"
+  storage_account_id    = azurerm_storage_account.cdn.id
+  container_access_type = "container"
+}
+
 resource "azurerm_storage_blob" "healthcheck" {
   name                   = "healthcheck.txt"
   storage_account_name   = azurerm_storage_account.cdn.name
@@ -72,6 +78,15 @@ resource "azurerm_storage_blob" "healthcheck" {
   content_type           = "text/plain"
 }
 
+resource "azurerm_storage_blob" "index" {
+  name                   = "index.html"
+  storage_account_name   = azurerm_storage_account.cdn.name
+  storage_container_name = azurerm_storage_container.root.name
+  type                   = "Block"
+  source_content         = ""
+  content_type           = "text/html"
+}
+
 module "cdn" {
   source  = "pagopa-dx/azure-cdn/azurerm"
   version = "~> 0.3"