kosmonavtika / nixos-infect

[GPLv3+] install nixos over the existing OS in a DigitalOcean droplet (and others with minor modifications)

This script aims to install NixOS on Digital Ocean droplets, Vultr servers, or OVH Virtual Private Servers (starting from distros that these services upports out of the box)

Source Distros

This script has been tested and can install NixOS from the following source distros:

On Digital Ocean:

• Fedora 24 x64
• Ubuntu 16.04 x64

On Vultr:

• Ubuntu 18.10 x64

On OVH Virtual Private Servers (experimental):

• Debian

YMMV with any other hoster + image combination.

If you have a OpenVZ based virtualization solution then this, or any other OS takeover script will not work, this is fundamental to how OpenVZ works.

Considerations

nixos-infect is so named because of the high likelihood of rendering a system inoperable. Use with caution and preferably only on newly-provisioned systems.

WARNING NB: This script wipes out the targeted host's root filesystem when it runs to completion. Any errors halt execution. It's advised to run with bash -x to help debug, as often a failed run leaves the system in an inconsistent state, requiring a rebuild (in DigitalOcean panel: Droplet Settings -> "Destroy" -> "Rebuild from original").

Digital Ocean

TO USE:

• Add any custom config you want (see notes below)
• Deploy the droplet indicated at the top of the file, enable ipv6, add your ssh key
• cat customConfig.optional nixos-infect | ssh root@targethost

Alternatively, use the user data mechamism by supplying the lines between the following cat and EOF in the Digital Ocean Web UI (or HTTP API):

#cloud-config

runcmd:
  - curl https://raw.githubusercontent.com/elitak/nixos-infect/master/nixos-infect | PROVIDER=digitalocean NIX_CHANNEL=nixos-18.09 bash 2>&1 | tee /tmp/infect.log

Potential tweaks:

• /etc/nixos/{,hardware-}configuration.nix: rudimentary mostly static config
• /etc/nixos/networking.nix, networking settings determined at runtime tweak if no ipv6, different number of adapters, etc.

#cloud-config
write_files:
- path: /etc/nixos/host.nix
  permissions: '0644'
  content: |
    {pkgs, ...}:
    {
      environment.systemPackages = with pkgs; [ vim ];
    }
runcmd:
  - curl https://raw.githubusercontent.com/elitak/nixos-infect/master/nixos-infect | PROVIDER=digitalocean NIXOS_IMPORT=./host.nix NIX_CHANNEL=nixos-18.09 bash 2>&1 | tee /tmp/infect.log

Vultr

To set up a NixOS Vultr server, instantiate an Ubuntu box with the following "Startup Script":

#!/bin/sh

curl https://raw.githubusercontent.com/elitak/nixos-infect/master/nixos-infect | PROVIDER=vultr NIX_CHANNEL=nixos-18.09 bash

Allow for a few minutes over the usual Ubuntu deployment time for NixOS to download & install itself.

Motivation

Motivation for this script: nixos-assimilate should supplant this script entirely, if it's ever completed. nixos-in-place was quite broken when I tried it, and also took a pretty janky approach that was substantially more complex than this (although it supported more platforms): it didn't install to root (/nixos instead), left dregs of the old filesystem (almost always unnecessary since starting from a fresh deployment), and most importantly, simply didn't work for me! (old system was being because grub wasnt properly reinstalled)