NixOS Configuration

Personal NixOS configuration managing multiple machines using Nix Flakes and flake-parts.

Systems

Infrastructure

Host	Role	Hardware	Status
galactica	Main server (media, databases, backups)	Intel i5-1340P, 12c/16t, 32GB, ~45TB	Online
basestar	Public-facing services (*.arsfeld.dev)	ARM Neoverse-N1, 4c, 24GB (Oracle Cloud)	Online
router	Network router	Intel N5105, 4c, 8GB	Offline
r2s	Backup router + home automation	Rockchip RK3328 ARM, 4c, 1GB	Offline
pegasus	Secondary server	Intel i5-4430, 4c, 16GB, ~18TB	Online

Embedded

Host	Role	Status
octopi	OctoPrint	Offline
raspi3	Raspberry Pi 3	Offline

Desktops & Laptops

Host	Role	Hardware	Status
raider	Desktop (GNOME, gaming, dev)	i5-12500H, RX 6650 XT, 32GB, ~4TB	Online
blackbird	ASUS ROG Zephyrus G14 laptop	-	Active

See HARDWARE.md for detailed disk and CPU specs.

Tiers

Hosts are grouped into deployment tiers (defined in flake-modules/hosts.nix as tiers):

Tier	Hosts	Meaning
tier1	galactica, basestar, raider	Always on, should always be deployed

Tiers are exposed as Colmena tags, so you can deploy a whole tier at once:

colmena apply --on @tier1     # deploy all tier-1 hosts

Features

• Modular Architecture - Opt-in constellation modules for services, media, backups, observability, and more
• Auto-Discovery - Hosts and modules loaded automatically via haumea
• Service Registry - Centralized port assignments, auth bypass, Tailscale exposure, and CORS config
• Container Orchestration - Podman/Docker-based media stack with declarative volume and network config
• DNS & Routing - *.arsfeld.one (internal via cloudflared), *.arsfeld.dev (public), *.bat-boa.ts.net (Tailscale)
• Automated Deployments - Colmena (primary) with aarch64 cross-compilation, nixos-rebuild fallback
• Secret Management - sops-nix with per-host and shared secrets
• Binary Caching - Attic server for faster builds
• Remote Builders - aarch64 builds via basestar host
• Declarative Everything - Including disk partitioning (disko)
• CI/CD - GitHub Actions builds all hosts, pushes to Attic cache, weekly flake updates

Quick Start

# Enter development shell
nix develop

# Deploy to one or more hosts
just deploy galactica
just deploy galactica basestar

# Build locally without deploying
just build <hostname>

# Fresh install on new hardware
just install <hostname> <target-ip>

# Format all Nix files
just fmt

Project Structure

flake.nix              # Flake entry point (nixpkgs-25.11, flake-parts)
flake-modules/         # Flake-parts modules
  lib.nix              #   Core utilities, haumea loaders, overlays
  hosts.nix            #   Auto-discovers hosts from hosts/ directories
  colmena.nix          #   Colmena deployment config
  deploy.nix           #   deploy-rs config (currently broken with Nix 2.32+)
  dev.nix              #   Development shell
  checks.nix           #   Pre-commit hooks, formatter
  images.nix           #   SD card, kexec, and installer ISO images
hosts/                 # Per-host configurations (auto-discovered)
modules/               # All NixOS modules (auto-loaded by haumea)
  constellation/       #   Opt-in feature modules
  services/            #   Service group modules (media, home apps, network)
  media/               #   Media stack (config, gateway, components)
home/                  # Home Manager configurations
packages/              # Custom Nix derivations (auto-loaded by haumea)
secrets/               # Encrypted secrets (sops/*.yaml)

Constellation Modules

Hosts compose their configuration by enabling modules via constellation.<module>.enable = true:

Module	Purpose
common	Base config: Nix settings, caches, SSH, Tailscale, Avahi
users	User accounts, SSH keys, sudo
sops	sops-nix secret management
docker / podman	Container runtimes
backup	Automated rustic/restic backups
gnome / cosmic / niri	Desktop environments
gaming	Gaming environment (Steam, etc.)
development	Dev tools (Docker, Node, Python, Go, Rust)
virtualization / project-vms	KVM/libvirt VMs
home-assistant	Home automation
vpn-exit-nodes	Tailscale exit nodes via AirVPN/Gluetun
observability-hub	Central Prometheus/Loki hub
metrics-client / logs-client / netdata-client	Observability agents
media-sync / tablet-sync	File synchronization
opencloud / email	Cloud storage, email

Tooling

• Nix Flakes + flake-parts - Reproducible, modular configurations
• Colmena - Primary deployment tool (parallel, cross-compilation)
• Home Manager - User environment management
• sops-nix - Secret management
• disko - Declarative disk partitioning
• haumea - Automatic module/package discovery
• Attic - Binary cache
• Tailscale - VPN mesh network

Documentation

• CLAUDE.md - Development and deployment instructions
• HARDWARE.md - Hardware inventory and specs

License

Personal use. Feel free to take inspiration for your own configurations.