Dotfiles

Personal dotfiles managed with a hybrid approach using GNU Stow and Nix.

Designed to:

• Work on non-Nix (that is, imperative package manager-powered) systems with GNU Stow
• Integrate cleanly into Nix-based setups (Home Manager / NixOS)

GNU Stow

Usage tips:

• how to stow somewhere other than $HOME:
  sudo stow -t <target_dir> <source_dir>

Nix

Nix has a somewhat steep learning curve. These notes are primarily for myself to help with building a stable mental model of how the system is structured.

Nix triad

1. Nix package manager

2. Nix language

3. NixOS

The main question Nix answers:

how does one build and deploy software in a fully reproducible, conflict-free way?

Nix package manager is the central element of the solution. A "package" is just a Nix (the language) build expression that produces some files in /nix/store with a name that includes a specific hash based on all inputs used to build the package (as opposed to, for example, outputs that are used to ensure the integrity of the build artefacts transferred over an untrusted channel)

Nix package manager

Use case:
Replacement of the native package manager apt, pacman, etc.

How:

nix + flakes + home manager

(There's an outdated method that involves using nix-env. It is imperative and results in configurations that are not easily reproducible)

1. Install home manager: nix run home-manager/master -- init --switch

   • installation creates ~/.config/home-manager/home.nix
   • configure home.nix (Nix language, declarative)
   • apply config: home-manager switch

2. Flakes: use flake.nix file inside the Home Manager's working dir (~/.config/home-manager/flake.nix) Nix generates flake.lock, pins the packages to a specific commit

3. To update packages (e.g. nixpkgs as named in flake.nix):

   • nix flake update (if using flakes) or nix-channel --update
   • switch

Note: Flakes address the class of problems similar to what Cargo.toml and package-json.lock do. They are a modern way to pin particular versions of packages (and other inputs) used in the (reproducible) system. Home Manager is a layer on top of Nix that manages user packages and (optionally) dotfiles.

Points of concern:

1. programs.<program>.enable and BYOC (bring your own config) will create conflict as Home Manager will try to "own" the path.
2. external config files must live either inside Home Manager's dir or within nix/store. The so-called pure evaluation has to be unset in order for absolute paths to work

Nix language

TODO: write as you go

NixOS

Why: Reproducible system configuration: kernel, services, packages, config files. Everything is described in configuration.nix Running nixos-rebuild switch makes the system match the declaration exactly.

Per-project dev environments

1. nix-shell with a shell.nix declaration
2. flakes
3. devShells