I have azurerm and azureapi providers that are subscription specific. E.g.,

provider "azurerm" {
  alias                      = "first"
  tenant_id                  = "<>"
  subscription_id            = var.subscription_id
  skip_provider_registration = true
  use_oidc                   = true
  features {}
}


provider "azapi" {
  alias           = "first-api"
  tenant_id       = "<>"
  subscription_id = var.subscription_id
  use_oidc        = true
}

I then also use terraform config files to change out the subscription_id.

I would like to deploy the same set of resources across multiple subscriptions in one config file but not others. That is, for dev.tfvars subscription_id is “” but in prod.tfvars it would have a value.

I’m not sure the best way to do this because if I try to use “” for the subscription id I am getting failures.

provider "azurerm" {
  alias                      = "second"
  tenant_id                  = "<>"
  subscription_id            = var.other_subscription_id <-- defaulted to "" in the variables
  skip_provider_registration = true
  use_oidc                   = true
  features {}
}


provider "azapi" {
  alias           = "second-api"
  tenant_id       = "<>"
  subscription_id = var.other_subscription_id
  use_oidc        = true
}

yields:

Error: building account: unable to configure ResourceManagerAccount: subscription ID could not be determined and was not specified

  with provider["registry.terraform.io/hashicorp/azurerm"].second,
  on provider.tf line 81, in provider "azurerm":
  81: provider "azurerm" {

I’m considering breaking the places I use these providers out into a separate module but according to https://developer.hashicorp.com/terraform/language/modules/develop/providers all providers are global and so it won’t work.

Is there a way to make a provider optional so it will only be loaded if I need it? Or is my reading of the Docs incorrect?