The `terraform_required_providers` rule fails to detect provider usage in modules and providers using `for_each`

[simao-silva]

TFLint Version

tflint v0.59.1

Terraform Version

OpenTofu v1.10.6

Description

The terraform_required_providers rule does not recognize provider dependencies under the following conditions:

• Providers are declared with for_each and alias
• Modules use for_each and pass providers via the providers block with dynamic references like kubernetes.kubernetes[each.key]

As a result, TFLint reports missing required_providers entries even though the providers are correctly used:

Failed to check ruleset; failed to check "terraform_required_providers" rule: main.tf:30,18-49: Invalid expression; A single static variable reference is required: only attribute access and indexing with constant keys. No calculations, function calls, template expressions, etc are allowed here., and 1 other diagnostic(s)

Example

provider "kubernetes" {
  for_each               = var.clusters
  alias                  = "kubernetes"
  host                   = "https://${module.kubernetes[each.key].cluster_endpoint}"
  cluster_ca_certificate = sensitive(base64decode(module.kubernetes[each.key].cluster_ca_certificate))
  token                  = sensitive(module.kubernetes[each.key].cluster_access_token)
}

module "service_account" {
  for_each = module.kubernetes
  providers = {
    kubernetes = kubernetes.kubernetes[each.key]
  }
(...)

---

Expected Behavior

TFLint should detect that the kubernetes provider is used in the module via the providers mapping and not require an explicit required_providers block if the provider is already declared in the root configuration with for_each.

[bendrucker]

As a result, TFLint reports missing required_providers entries

The output is a parsing error, not a report of a missing entry. At the moment TFLint supports Terraform syntax/structure and so it's erroring trying to parse something it doesn't understand.