Terraform Multi-providers VS explicit passing within Module - terraform

Question

I have seen similar questions but the answers there rather addressed the formatting or workarounds which weren't that "clean". I will try to summarize my issue and hopefully can get some lean/clean solution. Thank you in advance guys!
I am creating AKS namespaces via Kubernetes provider in Terraform. Since I have 3 clusters, I want to be able to control which provider should be used to create the namespace. e.g. dev / prod
Folder structure
.terraform
├───modules
└───namespace.tf
└───module_providers.tf
└───main-deploy
└───main.tf
└───main_provider.tf
My Module // namespace.tf
# Create Namespace
resource "kubernetes_namespace" "namespace-appteam" {
metadata {
annotations = {
name = var.application_name
}
labels = {
appname = var.application_name
}
name = var.application_name
}
}
My main.tf file
module "appteam-test" {
source = "../modules/aks-module"
application_name = "dev-app"
providers = {
kubernetes.dev = kubernetes.dev
kubernetes.prod = kubernetes.prod
}
}
Now since I have passed 2 providers in the main.tf module block! How do I control that the resource I am creating in namespace.tf file should use Dev or Prod provider? In short, how does the module know which resource to create with what provider if several are passed.
Note: I have required_providers defined in the module_providers.tf and providers in main_provider.tf folder.
module_provider.tf
terraform {
required_providers {
azurerm = {
source = "hashicorp/azurerm"
version = "3.20.0"
}
azuread = {
source = "hashicorp/azuread"
version = "2.27.0"
}
kubernetes = {
source = "hashicorp/kubernetes"
version = "2.12.1"
}
}
}
Main_provider.tf
provider "azuread" {
alias = "AD"
}
provider "azurerm" {
alias = "default"
features {}
}
provider "kubernetes" {
alias = "dev"
}
provider "kubernetes" {
alias = "prod"
}

Answer 1

You need to add alias to all your providers.
provider "kubernetes" {
alias = "dev"
}
provider "kubernetes" {
alias = "stage"
}
In your main.tf file. Pass providers in module like following:
providers = {
kubernetes.dev = kubernetes.dev
kubernetes.stage = kubernetes.stage
}
Now in the module_provider.tf file. You need to pass configuration_aliases
kubernetes = {
source = "hashicorp/kubernetes"
version = "2.12.1"
configuration_aliases = [ kubernetes.dev, kubernetes.stage ]
}
Once all the configurations are in place. You can specify the provider explicitly for resources you want. Your namespace.tf file will look like
resource "kubernetes_namespace" "namespace-appteam-1" {
provider = kubernetes.dev
metadata {
annotations = {
name = var.application_name
}
labels = {
appname = var.application_name
}
name = var.application_name
}
}
resource "kubernetes_namespace" "namespace-appteam-2" {
provider = kubernetes.stage
metadata {
annotations = {
name = var.application_name
}
labels = {
appname = var.application_name
}
name = var.application_name
}
}