NixOS Vagrant Plugin

This plugin makes working with NixOS guests in Vagrant a bit nicer:

• Allow network configurations
• Allow hostname setting
• Provide nix provisioning

Install:

$ vagrant plugin install vagrant-nixos

Example Vagrantfile

Vagrant.configure("2") do |config|

    # use a suitable NixOS box
    config.vm.box = "nixos-14.02-x86_64"

    # set hostname
    config.vm.hostname = "nixy"

    # Setup networking
    config.vm.network "public_network", :bridge => 'en1: Wi-Fi (AirPort)'
    config.vm.network "private_network", :ip => "172.16.16.16"

    # Add the htop package
    config.vm.provision :nixos, :expression => {
        environment: {
            systemPackages: [ :htop ]
        }
    }

end

In the above Vagrantfile example we provision the box using the :expression method, which will perform a simple ruby -> nix conversion. :expression provisioning creates a nix module that executes with pkgs in scope. It is roughly equivilent to the below version that uses the :inline method.

config.vm.provision :nixos, :inline => %{
    {config, pkgs, ...}: with pkgs; {
        environment.systemPackages = [ htop ];
    }
}, :NIX_PATH => "/custom/path/to/nixpkgs"

The above example also shows the optional setting of a custom NIX_PATH path.

If you need to use functions or access values using dot syntax you can use the Nix module:

config.vm.provision :nixos, :expression => {
    services: {
        postgresql: {
            enable: true,
            package: Nix.pkgs.postgresql93,
            enableTCPIP: true,
            authentication: Nix.lib.mkForce(%{
                local all all              trust
                host  all all 127.0.0.1/32 trust
            }),
            initialScript: "/etc/nixos/postgres.sql"
        }
    }
}   

How it works

In nixos we don't mess around with the files in /etc instead we write expressions for the system configuration starting in /etc/nixos/configuration.nix.

This plugin sets some ground rules for nixos boxes to keep this configuration clean and provisioning possible.

Box creators should ensure that their configuration.nix file imports an nix module /etc/nixos/vagrant.nix which will be overwritten by vagrant-nixos during vagrant up or vagrant provision.

See the configuration in our NixOS packer template for an example.

Issues

It's a bit slow on the initial boot/provision at the moment as it must run nixos-rebuild several times. This is far from ideal I'm sure I'll find a better place to hook in the rebuild step soon.