feat(terraform): define storage recovery vault and policy

the vault is where backups are stored
the policy defines the frequency and retention of backups

these are linked to the storage account via azurerm_backup_container_storage_account

terraform/storage.tf

@@ -23,6 +23,45 @@ resource "azurerm_storage_account" "main" {
   }
 }
 
+resource "azurerm_recovery_services_vault" "main" {
+  name                = "rsvcdtcalitp${lower(local.env_letter)}001"
+  location            = data.azurerm_resource_group.main.location
+  resource_group_name = data.azurerm_resource_group.main.name
+  sku                 = "Standard"
+  soft_delete_enabled = true
+
+  lifecycle {
+    ignore_changes = [tags]
+  }
+}
+
+resource "azurerm_backup_container_storage_account" "main" {
+  resource_group_name = data.azurerm_resource_group.main.name
+  recovery_vault_name = azurerm_recovery_services_vault.main.name
+  storage_account_id  = azurerm_storage_account.main.id
+}
+
+resource "azurerm_backup_policy_file_share" "policy" {
+  name                = "${azurerm_storage_account.main.name}-backup-policy"
+  resource_group_name = data.azurerm_resource_group.main.name
+  recovery_vault_name = azurerm_recovery_services_vault.main.name
+  timezone            = "UTC"
+
+  backup {
+    frequency = "Daily"
+    time      = "14:00"
+  }
+
+  retention_daily {
+    count = 1
+  }
+
+  retention_weekly {
+    count    = 5
+    weekdays = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
+  }
+}
+
 resource "azurerm_storage_share" "data" {
   name                 = "benefits-data"
   storage_account_name = azurerm_storage_account.main.name