This repository contains code to build and run NixOS in virtual machines on macOS. It uses vfkit as qemu doesn't support apple´s virtualisation framework, and UTM isn't as easy to configure from nix expressions.

It is currently not much more than a quick weekend hack and therefore experimental, neither stable nor feature-complete - but fun & promising!

To start a graphical, rather minimal VM run:

$ nix run .\#nixosConfigurations.minimal-vm.config.system.build.vm -L

The local (currently empty) directory persistent gets mounted to /persistent in the guest via `virtio-fs``.

minimal-vm has a static mac address defined in virtualisation.macAddress, which can be used to derive its ipv6 link local address. A legacy ipv4 address can be acquired by parsing /var/db/dhcpd_leases. A helper script to do both is included in this repository:

$ nix run .\#get-vm-ip -- minimal-vm
fe80::f425:e2ff:fe48:581e%bridge100
$ nix run .\#get-vm-ip -- minimal-vm -4
192.168.64.2

Set virtualisation.graphics = true; in configuration.nix.

• Booting a closure, directly from kernel and initrd.
• Mounting host file systems via virtio-fs. Used for a writable overlay over the hosts nix store by default*
• Rosetta - by leveraging vfkit´s and NixOS´ Rosetta integrations you can build derivations for both aarch64-linux and x86_64-linux in the VM.
• Bridged networking via virto-net.
• Graphical mode with virtio-gpu. vfkit´s GUI seems to be still limited though, e.g. no copy & paste support(?).

• Persistence: virtio-blk is quite easy to use, just needs a nice interface on the module side. I didn't bother so far, as virtio-fs works well enough atm.
  There's a branch disk in which I played around with formatting a virtio-blk device wich systemd-repart on first boot, but didn't finish that yet.
• VM Tests with our vfkit VMs would be awesome.
• Might be worth a try to (optionally) replace qemu in nix-darwins linux-builder vm for rosetta.
• This list: There's much to explore & still a bit to clean-up.