Azure Function App has the ability to require authentication as protection from unwanted access. It is considered best practice to use authentication/authorization methodologies based on identity. For more information on securing Function Apps, see the Azure documentation.
Resources:
https://learn.microsoft.com/en-us/azure/azure-functions/security-concepts?tabs=v4
In Azure Console -
In Terraform -
References:
https://learn.microsoft.com/en-us/azure/azure-functions/
https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/windows_function_app#auth_settings