thoughts/data/nixos-vps2day.md

I feel more and more limited by macOS when it comes to creative computational work. One of the systems I've read good things about, and that I fully support the philosophy around is NixOS. I decided to test it in a VPS.

The top recommended hoster of NixOS is vps2day, which seems like a basic but okay hoster for testing the capabilities of the OS. What I found was that there were no online installation for NixOS on vps2day. After a bit back and forth I found that other guides were also working on vps2day. This article describes the procedure to get the system up and running (following the standard installation guide).

The installation of NixOS was something new to me compared with the installer of other operating systems. NixOS by default only boots to a shell. With that shell the NixOS configuration files needs to be setup, which in turn installs things such as Grub on a given disk. In other words, when vps2day boots you into console the OS isn't installed yet.

% sudo su

# partition the disk with swap
% parted /dev/vda -- mklabel msdos
% parted /dev/vda -- mkpart primary 1MiB -8GiB
% parted /dev/vda -- mkpart primary linux-swap -8GiB 100%

% mkfs.ext4 -L nixos /dev/vda1
% mkswap -L swap /dev/vda2

# mount the nixos disk and enable swap
% mount /dev/disk/by-label/nixos /mnt
% swapon /dev/vda2

# Generate configuration files
% nixos-generate-config --root /mnt

# Install a sensible text editor
% nix-env -f '<nixpkgs>' -iA emacs

% emacs /mnt/etc/nixos/configuration.nix

You are now in the configuration file which defines the installation. For vps2day the following works to get a minimal server up and running.:

{ config, pkgs, ... }:

{
  imports =
    [
      ./hardware-configuration.nix
    ];

  boot.loader.grub.enable = true;
  boot.loader.grub.version = 2;
  boot.loader.grub.device = "/dev/vda"; # or "nodev" for efi only

  # networking.hostName = "nixos"; # Define your hostname.
  networking.useDHCP = false;
  networking.interfaces.ens3.useDHCP = true;

  time.timeZone = "Europe/Oslo";

  environment.systemPackages = with pkgs; [
    wget vim emacs
  ];

  programs.mtr.enable = true;
  programs.gnupg.agent = { enable = true; enableSSHSupport = true; };

  services.openssh.enable = true;

  networking.firewall.allowedTCPPorts = [ 22 ];

  # Define a user account. Don't forget to set a password with ‘passwd’.
  users.users.thetom = {
     isNormalUser = true;
     extraGroups = [ "wheel" ]; # Enable ‘sudo’ for the user.
  };

  system.stateVersion = "19.09";

}

With that configuration, the provisioning of the server is ready.

# Install bootloader and other according to configuration.nix
% nixos-install
% reboot

The login prompt should be up and running and you can SSH into the server after the reboot.

Finally upgrade to the current version according to the docs:

% nix-channel --add https://nixos.org/channels/nixos-21.05 nixos
% nix-channel --list | grep nixos
% nixos-rebuild switch --upgrade
% reboot

What is nice with this setup is that the configuration options are be documented in configuration.nix - so if we ever need to this again it can be simply achieved with a script in e.g. Drist.