Ephemeral variables (#3108)

Signed-off-by: Andrei Ciobanu <andrei.ciobanu@opentofu.org>
Signed-off-by: Christian Mesh <christianmesh1@gmail.com>

internal/command/e2etest/testdata/ephemeral-errors/variables/in-data-source.tf.disabled

@@ -0,0 +1,6 @@
+// Running this configuration is expected to have an error since data sources are not allowed
+// to use ephemeral values at all.
+data "simple_resource" "test_data1" {
+  provider = simple.s1
+  value    = var.in
+}

internal/command/e2etest/testdata/ephemeral-errors/variables/in-non-ephemeral-mod-variable.tf.disabled

@@ -0,0 +1,6 @@
+// Running this configuration is expected to return an error since variables not configured as ephemeral
+// are not allowed to use ephemeral values.
+module "test" {
+  source = "./non-ephemeral-mod"
+  in     = var.in
+}

internal/command/e2etest/testdata/ephemeral-errors/variables/in-non-ephemeral-output.tf.disabled

@@ -0,0 +1,5 @@
+// Running this configuration is expected to have an error since output blocks not configured as ephemeral
+// are not allowed to use ephemeral values.
+output "out" {
+  value = var.in
+}

internal/command/e2etest/testdata/ephemeral-errors/variables/in-resources-regular-fields.tf.disabled

@@ -0,0 +1,6 @@
+// Running this configuration is expected to have an error since `value` is not a write-only argument.
+// Regular resources arguments are not allowed to use ephemeral variables and values
+resource "simple_resource" "test_res" {
+  provider = simple.s1
+  value = var.in
+}

internal/command/e2etest/testdata/ephemeral-errors/variables/main.tf

@@ -0,0 +1,28 @@
+// the provider-plugin tests uses the -plugin-cache flag so terraform pulls the
+// test binaries instead of reaching out to the registry.
+terraform {
+  required_providers {
+    simple = {
+      source = "registry.opentofu.org/hashicorp/simple"
+    }
+  }
+}
+
+provider "simple" {
+  alias = "s1"
+}
+
+variable "in" {
+  ephemeral = true
+  type = string
+}
+
+variable "in2" {
+  ephemeral = true
+  type = string
+  default = "in2 default value just to test the validations"
+  validation {
+    condition = var.in2 != "fail_on_this_value"
+    error_message = "variable 'in2' value '${var.in2}' cannot be 'fail_on_this_value'"
+  }
+}

internal/command/e2etest/testdata/ephemeral-errors/variables/non-ephemeral-mod/main.tf

@@ -0,0 +1,8 @@
+// Module that is used strictly to test passing in and out ephemeral variables.
+variable "in" {
+  type = string
+}
+
+output "out" {
+  value = var.in
+}