add regression test for special-args issue in terraform

Author: Mic92

terraform/flake-module.nix

@@ -5,6 +5,18 @@
     modules = [
       ../tests/modules/system-to-install.nix
       inputs.disko.nixosModules.disko
+      (args: {
+        # Example usage of special args from terraform
+        networking.hostName = args.terraform.hostname or "nixos-anywhere";
+
+        # Create testable files in /etc based on terraform special_args
+        environment.etc = {
+          "terraform-config.json" = {
+            text = builtins.toJSON args.terraform or { };
+            mode = "0644";
+          };
+        };
+      })
     ];
   };
 

terraform/nix-build/nix-build.sh

@@ -31,12 +31,17 @@ else
 
   # grab flake nar from error message
   flake_rel="$(echo "${attribute}" | cut -d "#" -f 1)"
-  # e.g. flake_rel="."
-  flake_dir="$(readlink -f "${flake_rel}")"
-  flake_nar="$(nix flake prefetch "${flake_dir}" --json | jq -r '.hash')"
+
+  # Use nix flake prefetch to get the flake into the store, then use path:// URL with narHash
+  prefetch_result="$(nix flake prefetch "${flake_rel}" --json)"
+  store_path="$(echo "${prefetch_result}" | jq -r '.storePath')"
+  nar_hash="$(echo "${prefetch_result}" | jq -r '.hash')"
+  flake_url="path:${store_path}?narHash=${nar_hash}"
+
   # substitute variables into the template
-  nix_expr="(builtins.getFlake ''file://${flake_dir}/flake.nix?narHash=${flake_nar}'').${config_path}.extendModules { specialArgs = builtins.fromJSON ''${special_args}''; }"
+  nix_expr="(builtins.getFlake ''${flake_url}'').${config_path}.extendModules { specialArgs = builtins.fromJSON ''${special_args}''; }"
   # inject `special_args` into nixos config's `specialArgs`
+  
   # shellcheck disable=SC2086
   out=$(nix build --no-link --json ${options} --expr "${nix_expr}" "${config_attribute}")
 fi

terraform/tests/nix-build-special-args.tftest.hcl

@@ -0,0 +1,43 @@
+# Terraform Test Configuration for nix-build module with special_args
+# Tests the fix for nested flakes in git repositories
+# Run with: tofu test
+
+variables {
+  test_name_prefix = "tftest-nix-build-special-args"
+}
+
+# Test: nix-build module with special_args using terraform-test configuration
+run "validate_nix_build_special_args" {
+  command = plan
+
+  module {
+    source = "../nix-build"
+  }
+
+  variables {
+    attribute = ".#nixosConfigurations.terraform-test.config.system.build.toplevel"
+    special_args = {
+      terraform = {
+        hostname      = "special-args-test-host"
+        ip_address    = "192.168.1.100"
+        environment   = "testing"
+        deployment_id = "test-001"
+      }
+    }
+  }
+
+  assert {
+    condition     = var.special_args.terraform.hostname == "special-args-test-host"
+    error_message = "special_args should preserve hostname value"
+  }
+
+  assert {
+    condition     = var.special_args.terraform.environment == "testing"
+    error_message = "special_args should preserve environment value"
+  }
+
+  assert {
+    condition     = var.attribute == ".#nixosConfigurations.terraform-test.config.system.build.toplevel"
+    error_message = "should use terraform-test configuration"
+  }
+}

tests/modules/system-to-install.nix

@@ -1,10 +1,10 @@
-{ modulesPath, self, ... }: {
+{ modulesPath, self, lib, ... }: {
   imports = [
     (modulesPath + "/testing/test-instrumentation.nix")
     (modulesPath + "/profiles/qemu-guest.nix")
     (modulesPath + "/profiles/minimal.nix")
   ];
-  networking.hostName = "nixos-anywhere";
+  networking.hostName = lib.mkDefault "nixos-anywhere";
   documentation.enable = false;
   hardware.enableAllFirmware = false;
   networking.hostId = "8425e349"; # from profiles/base.nix, needed for zfs