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This repository contains my dotfiles and a Nix flake that supports multiple hosts (machines) with a shared base and per-host configuration.

• On NixOS: hosts are built via nixosConfigurations.
• On non-NixOS (e.g., Ubuntu): hosts are applied via Home Manager using homeConfigurations.

Bootstrap

pip install pipx ansible
ansible-playbook --ask-become-pass ansible/main.yml
# Then apply dotfiles with dotter
dotter

NixOS: multi-host layout

• nix/base/packages.nix — packages installed on all hosts
• nix/hosts//
  • configuration.nix — host-specific NixOS configuration
  • hardware-configuration.nix — generated per-machine
  • packages.nix — extra packages for this host
• nix/flake.nix — exposes each host under nixosConfigurations

Current hosts:

• limgrave — my main system
• carpates — scaffolded/minimal, ready to extend

Naming rule (important)

Your machine hostname must match the Nix flake host name. For example:

• networking.hostName = "limgrave" in the host configuration
• The flake exports nixosConfigurations.limgrave
• The system hostname (output of hostname -s) is limgrave

This allows the upgrade function to pick the right configuration automatically.

Build or switch

From repo root:

# Limgrave (current system)
sudo nixos-rebuild switch --flake ./nix#limgrave

# carpates (on target machine)
sudo nixos-rebuild switch --flake ./nix#carpates
# Or during install:
# nixos-install --flake <repo-path>/nix#carpates

Upgrades: nix_upgrade

A convenience Fish function is provided in fish/conf.d/functions.fish: nix_upgrade. It updates flake inputs and rebuilds the system using a host name that matches the machine hostname.

Usage:

# Automatic: uses (hostname -s) → must match a host in nix/flake.nix
nix_upgrade

# Override the host explicitly (useful for recovery or chroots)
nix_upgrade limgrave

What it does:

1. sudo nix flake update --flake /home/catalin/.dotfiles/nix
2. sudo nixos-rebuild switch --flake /home/catalin/.dotfiles/nix# --upgrade

Safety checks:

• Verifies nix/flake.nix exists
• Verifies the host is declared in nix/flake.nix
• Prints clear error if the hostname doesn’t map to a known host

Tip: ensure your system hostname matches one of the directories in nix/hosts/ and the entry under nixosConfigurations in nix/flake.nix.

Adding a new host

1. Create a directory: nix/hosts//
2. Add configuration files (start by copying limgrave and trimming, or use the minimal example from carpates)
3. Generate hardware config on the new machine:

sudo nixos-generate-config
# Move merge the generated hardware-configuration.nix into nix/hosts/<newhost>/

4. Add the host to nix/flake.nix under nixosConfigurations
5. Make sure networking.hostName = "" in the host configuration
6. Build or install:

sudo nixos-rebuild switch --flake ./nix#<newhost>
# or during install:
nixos-install --flake <repo-path>/nix#<newhost>

Notes

• Old single-host files nix/configuration.nix and nix/packages.nix are kept for reference but are not used by the flake. You can remove them once comfortable with the new layout.
• limgrave includes nix-snapd and Home Manager; carpates currently includes Home Manager only.

Nix on non-NixOS (Ubuntu, etc.)

You can also use this flake on non-NixOS systems (e.g., Ubuntu) via Home Manager. For that path, hosts are defined under homeConfigurations in nix/flake.nix and typically live next to their NixOS counterparts. In this repo, carpates is prepared for non-NixOS via Home Manager.

• Naming rule: your machine's hostname (output of hostname -s) should match the homeConfigurations.<host> entry. Example: carpates.
• Packages: non-NixOS hosts usually install user-scoped packages via Home Manager, using the shared base set from nix/base/packages.nix.

Prerequisites

• Install Nix (multi-user is recommended):

  sh <(curl -L https://nixos.org/nix/install) --daemon
  

• Enable flakes (if not already). On non-NixOS, set in /etc/nix/nix.conf or $XDG_CONFIG_HOME/nix/nix.conf:

  experimental-features = nix-command flakes
  

• Install Home Manager (no separate channel needed when using flakes; we can run it via nix run or install it on PATH):

  # Optional, to have `home-manager` on PATH:
  nix profile install github:nix-community/home-manager
  

Apply the configuration (non-NixOS)

From repo root:

# Use the prepared Home Manager host (example: carpates)
home-manager switch --flake ./nix#carpates
# If `home-manager` is not installed, you can run it via nix:
nix run github:nix-community/home-manager -- switch --flake ./nix#carpates

Upgrades (non-NixOS)

nix_upgrade also works on non-NixOS:

# Auto-detects host from (hostname -s) and runs Home Manager switch
nix_upgrade

# Or override explicitly
nix_upgrade carpates

What it does on non-NixOS:

• nix flake update --flake /home/catalin/.dotfiles/nix
• home-manager switch --flake /home/catalin/.dotfiles/nix#<host> (or nix run ... -- switch if HM is not on PATH)

NixOS vs. non-NixOS summary

• NixOS hosts are declared under nixosConfigurations and are applied with nixos-rebuild.
• non-NixOS hosts are declared under homeConfigurations and are applied with home-manager switch.
• The nix_upgrade function detects the OS and selects the correct path automatically based on the hostname.