○ NixOS

NixOS is a Linux distro which follows a path radically different from Ubuntu/Fedora/Arch/Gentoo, etc. The system configuration is no longer a stateful, imperative process. Instead, you describe your system using the Nix configuration language and a fresh system generation (something like a system image) is built and activated each time you're making a change to the system.

Simplifying, you can think about it as getting a completely fresh system on every change, except the directories when data is kept: /home, /var, log.

What does that mean in practice? Forget about keeping a script for setting up your system or your dotfiles. Forget about clearing up old configuration files. No more conflicts between package versions. If you have multiple machines, treat them like build configurations in programming languages and freely reuse modules with configuration. Same users on multiple systems? Done. Same configuration for a specific service/app? Done!

From 2023, I have been using NixOS for my server/homelab infrastructure. It is a step up from Ansible playbooks, I even dare to say that it's a paradigm shift. I am reluctant to switch my main laptops to NixOS, as it's not as easy to program on NixOS as it is to deploy software on it. Hopefully this will change in the future :)

Useful links:

• search.nixos.org - search engine for NixOS configuration options
• Nix Pills
• VimJoyer YouTube channel - high quality Nix tutorials
• An overview of Nix in practice
• Nix-ld - running "normal" binaries on NixOs
• Nix Phd thesis from Eelco Dolstra, the author of Nix
• NixOs egui

Tips & notes

• NixOS has excellent support for ZFS, arguably the most advanced filesystem currently on the market. Article about ZFS on the unofficial NixOS wiki
• Convert your system configuration into flake-based as soon as possible. It makes your system fully reproducible and makes it easier to use stuff like Agenix
  • https://wiki.nixos.org/wiki/Flakes
• Creating and maintaining custom SystemD services/timers is a breeze in NixOS
  • https://wiki.nixos.org/wiki/Systemd/User_Services
• There is a formatter key in Flake configuration. If you set it to a formatter program, use nix fmt to format your code

Switching configurations with confidence

My homelab consists of a VPS with a static IP and a server at my place. If I mess something up with the networking configuration (which happened more than I initially thought), I might break the VPN configuration to my homeserver. This would be far from perfect when I'm away from home as I'm unable to log in locally and fix the networking configuration.

I didn't want to install something like Tailscale or ZeroTier because I'm a purist because it's my homelab and I wanted to be independent!

The deployment procedure has been working for me for over 2 years and survived multiple configuration mishaps:

1. Run nixos-rebuild build before you make any modifications
2. Schedule a reboot in 15 minutes
3. Run nixos-rebuild test
4. Run VPN connectivity tests (simple pings via some script or via ansible)
5. Cancel the scheduled reboot
6. Run nixos-rebuild switch