Run NixOS VM on macOS machine

This repo provides an example of running a NixOS VM on your macOS machine using new features in nixpkgs. It contains results of the work done for issue NixOS/nixpkgs#108984.

TL;DR

Run this and you will get a working VM on your macOS machine, built with NixOS configuration from this flake:

nix run github:YorikSar/nixos-vm-on-macos

To exit, run sudo poweroff or press Ctrl-a-x

Setting up

Here I will list errors that you might encounter and how to address them.

Experimental features

error: experimental Nix feature 'nix-command' is disabled; use '--extra-experimental-features nix-command' to override

Flakes are still experimental in Nix, so if you didn't enable them in your config yet, you can do one of:

• run export NIX_CONFIG="extra-experimental-features = nix-command flakes" to temporary enable them in your current shell
• add line extra-experimental-features = nix-command flakes to your ~/.config/nix/nix.conf file to enable them for your current user
• add line extra-experimental-features = nix-command flakes to your /etc/nix/nix.conf file to enable them globally on your machine

Flake configuration settings

do you want to allow configuration setting 'extra-substituters' to be set to 'https://yoriksar-gh.cachix.org' (y/N)? y
do you want to permanently mark this value as trusted (y/N)? y
do you want to allow configuration setting 'extra-trusted-public-keys' to be set to 'yoriksar-gh.cachix.org-1:YrztCV1unI7qDV6IXmiXFig5PgptqTlUa4MiobULGT8=' (y/N)? y
do you want to permanently mark this value as trusted (y/N)? y

This flake provides configuration settings for using my cache hosted on Cachix. On the first run, Nix will ask you if you want to enable each of these settings (I recommend answer "yes") and whether you want to trust these settings in the future so that you don't have to reply to these questions every time.

Trust my substituter

warning: ignoring untrusted substituter 'https://yoriksar-gh.cachix.org'

If you see this line, it means that while your Nix trusts the configuration values, it doesn't trust substituter. Add these lines to your /etc/nix/nix.conf:

trusted-substituters = https://yoriksar-gh.cachix.org
trusted-public-keys = yoriksar-gh.cachix.org-1:YrztCV1unI7qDV6IXmiXFig5PgptqTlUa4MiobULGT8=

and then restart your Nix daemon with:

sudo launchctl kickstart -k system/org.nixos.nix-daemon

Linux builder is required

error: a 'aarch64-linux' with features {} is required to build '...', but I am a 'x86_64-darwin' with features {benchmark, big-parallel, nixos-test}

If you don't configure my substituter (see previous 2 sections) or change the configuration in any way, you will have to rebuild NixOS system configuration. Unfortunately, it requires you to have a remote builder configured for your machine with the appropriate Linux support. I will refer you to docs that describe how to set it up. You would still have to provide your own Linux machine though.

Host and guest architecture must match

qemu-system-x86_64: Unknown Error

If you're seeing this on your Apple Silicon machine, you're probably running Intel version of Nix that uses x86_64-darwin system by default. You can't run x86_64-linux machine on Apple Silicon at this point (will be fixed in nixpkgs eventually), and it would be very slow (Rosetta is of no help here), so you should stick to running aarch64-linux VM on your machine. To do so, add --system aarch64-darwin to your nix run and it will pick up the right package.

Broken sudo

[test@nixos:~]$ sudo poweroff
sudo: error in /etc/sudo.conf, line 0 while loading plugin "sudoers_policy"
sudo: /nix/store/kkn64rx0ns1kv8yadwclnwrny29n6inj-sudo-1.9.11p3/libexec/sudo/sudoers.so must be owned by uid 0
sudo: fatal error, unable to load plugins

This probably means that you're using single-user (daemon-less) Nix installation and all /nix/store paths are owned by you instead of root. By default, VM shares /nix/store with the host, so things like sudoers.so ends up with wrong permissions. This can be fixed by using a qcow image with all necessary store path for the VM. There's a special output that has already been build and cached for this. To use it, run

nix run github:YorikSar/nixos-vm-on-macos#withStoreImage

Note that it will download the image from the cache for you that weight about 1Gb.

There's a different issue

Feel free to ask about it in the original issue or in this repo's issues.