TFNFR34 - Using Feature Toggles

Updated on Dec 2, 2024 One minute to read Category-CodeStyle Class-Pattern Class-Resource Language-Terraform Lifecycle-BAU Persona-Contributor Persona-Owner Severity-MUST Type-NonFunctional Validation-TBD

ID: TFNFR34 - Category: Code Style - Using Feature Toggles

A toggle variable MUST be used to allow users to avoid the creation of a new resource block by default if it is added in a minor or patch version.

E.g., our previous release was v1.2.1 and next release would be v1.3.0, now we’d like to submit a pull request which contains such new resource:

resource "azurerm_route_table" "this" {
  location            = local.location
  name                = coalesce(var.new_route_table_name, "${var.subnet_name}-rt")
  resource_group_name = var.resource_group_name
}

A user who’s just upgraded the module’s version would be surprised to see a new resource to be created in a newly generated plan file.

A better approach is adding a feature toggle to be turned off by default:

variable "create_route_table" {
  type     = bool
  default  = false
  nullable = false
}

resource "azurerm_route_table" "this" {
  count               = var.create_route_table ? 1 : 0
  location            = local.location
  name                = coalesce(var.new_route_table_name, "${var.subnet_name}-rt")
  resource_group_name = var.resource_group_name
}