There was a feature request for the azurerm_app_service resource to support a file_system block inside the application_logs: https://github.com/terraform-providers/terraform-provider-azurerm/issues/4021
According to the comments on the same issue/feature request, this is supported since version 1.3.3 of the azurerm (Aug. 2019).
But looking at the documentation this does not seem to be the case: https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/app_service#logs - the application_logs block still only supports the azure_blob_storage.
does anyone now more about this? has this been removed again?