From aab534b894c60e69199aba4cc57b8b3f8fd1a8c2 Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Fri, 23 Oct 2020 17:33:10 +0200
Subject: [PATCH] nixos/nixos-build-vms: use `pkgs.qemu` for virtualisation

When I test a change e.g. in the module system manually, I usually use
`nixos-build-vms(8)` which also gives me a QEMU window where I can play
around in the freshly built VM.

It seems as this has changed recently when the default package for
non-interactive VM tests using the same framework was switched to
`pkgs.qemu_test` to reduce the closure size. While this is a reasonable
decision for our CI tests, I think that you really want a QEMU window of
the VM by default when using `nixos-build-vms(8)`.

[1] bc2188b083dfbbe749a221023e2960b60d4c8951
---
 .../modules/installer/tools/nixos-build-vms/build-vms.nix  | 7 ++++++-
 nixos/modules/testing/test-instrumentation.nix             | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/installer/tools/nixos-build-vms/build-vms.nix b/nixos/modules/installer/tools/nixos-build-vms/build-vms.nix
index 0c9f8522cc12..199e5f9206b1 100644
--- a/nixos/modules/installer/tools/nixos-build-vms/build-vms.nix
+++ b/nixos/modules/installer/tools/nixos-build-vms/build-vms.nix
@@ -6,7 +6,12 @@
 let
   nodes = builtins.mapAttrs (vm: module: {
     _file = "${networkExpr}@node-${vm}";
-    imports = [ module ];
+    imports = [
+      module
+      ({ pkgs, ... }: {
+        virtualisation.qemu.package = pkgs.qemu;
+      })
+    ];
   }) (import networkExpr);
 in
 
diff --git a/nixos/modules/testing/test-instrumentation.nix b/nixos/modules/testing/test-instrumentation.nix
index e9f5eac7f5f4..2986bd4c4e31 100644
--- a/nixos/modules/testing/test-instrumentation.nix
+++ b/nixos/modules/testing/test-instrumentation.nix
@@ -53,7 +53,7 @@ with import ../../lib/qemu-flags.nix { inherit pkgs; };
     #       or declare virtualisation.qemu.console option in a module that's always imported
     virtualisation.qemu = {
       consoles = lib.optional (options ? virtualisation.qemu.consoles) qemuSerialDevice;
-      package  = pkgs.qemu_test;
+      package  = lib.mkDefault pkgs.qemu_test;
     };
 
     boot.initrd.preDeviceCommands =