dotnix

Declarative system configuration used on my 2019 Intel Macbook Pro.

$ nix-info -m && date
 - system: `"x86_64-darwin"`
 - host os: `Darwin 22.5.0, macOS 10.16`
 - multi-user?: `yes`
 - sandbox: `no`
 - version: `nix-env (Nix) 2.15.1`
 - nixpkgs: `/nix/store/jlbslziyjj8clk62y4pr7fc23amm5npp-source`

Sat Jun 10 21:15:00 PDT 2023

• dotnix
  • Learn
    • System Configuration with Nix
    • Understanding dotnix
  • Do
    • Installation
    • Modifying the System Configuration
    • Updating the System Configuration
  • Learn and Do
    • How I Started
  • Resources

Learn

System Configuration with Nix

NixOS allows users to define the entire system configuration in a declarative manner using the Nix expression language. This includes specifying packages, services, users, and other system settings. The declarative nature of NixOS ensures that the system configuration is version-controlled, reproducible, and easy to share. It also simplifies system administration by providing a single source of truth for the entire system state.

Outside of NixOS, declarative system configuration can be achieved on MacOS through various Nix-based tools like home-manager and nix-darwin. The following tools work with both standard and flake-based approaches:

System Configuration	Platforms	Configuration File	Configuration Options	Notes
NixOS	NixOS	configuration.nix	Available in Manual or NixOS Options Search
Home-Manager	NixOS, Linux, MacOS	home.nix	accounts, home, launchd, nix, programs, services, systemd, targets.darwin, wayland, xdg, xsession	Can also be configured as NixOS module or nix-darwin module
Nix-Darwin	MacOS	darwin-configuration.nix	enviroment, homebrew, launchd, networking, nix, programs, services, system, users

Understanding dotnix

dotnix is a flake-based configuration powered by Home-Manager.

File	Purpose	Notes
home.nix	My system configuration via home-manager including: • apps (1Password, Firefox, VSCode) • dev settings (.git, .bashrc) • CLI tools (bat, fzf, jq) ...and more	• Home-Manager Manual - tool for declaratively managing system configuration, dotfiles, etc • Home-Manager Options & Options Search - pre-defined configurations available with home-manager • NixPkgs - package repository + binary cache with 100k+ available packages
flake.nix	Takes Nix expressions as input, then output things like package definitions, development environments, or, as is the case here, system configurations. For this specific repository, we can think of it as wrapping home.nix in order to provide it pinned dependencies and manage the outputs.	• Zero to Nix Glossary • xeiaso's Nix Flake Guides
flake.lock	Pins dependencies used in flake inputs
bin/apply-system.sh	Script to apply system configuration	Simple home-manager switch... invocation
bin/update-system.sh	Script to update dependencies	Simple nix flake update invocation

---

Software installed with dotnix is specified in following ways:

• Home-Manager Options
  • Via programs.* in home.nix
• Nixpkgs Package Set
  • Via home.packages in home.nix, corresponding to nixpkgs release at flake.nix:inputs.nixpkgs.url
• Flake Inputs
  • Via inputs in flake.nix and pinned in flake.lock

System-wide nix settings are specified in home.nix under the following declarations:

• nix.package
  • Determines which version of nix is used
    • Has matching declaration under home.packages.config.nix.package
• home.sessionVariables
  • Environment variables set at login
• nix.settings
  • Replaces configuration that's usually found at /etc/nix/nix.conf
  • Sets feature flags, binary cache keys and locations, etc
• nix.registry
  • Replaces configuration that's usually found at /etc/nix/registry.json
  • Same as default found at https://github.com/NixOS/flake-registry

    • "The flake registry serves as a convenient method for the Nix CLI to associate short names with flake URIs, such as linking nixpkgs to github:NixOS/nixpkgs/nixpkgs-unstable."

Do

Installation

1. Install nix

Follow the Zero-to-Nix Quickstart Guide for a flake-based nix installation.

2. Setup dotnix repo

$ mkdir -p ~/.config
$ cd ~/.config
$ git clone git@github.com:hkailahi/dotnix.git

3. Apply system configurations

$ cd ~/.config/dotnix/
$ ./bin/apply-system.sh

Modifying the System Configuration

1. Modify configuration files

For example, add a new package to install in home.nix or move to a newer release of nixpkgs in flake.nix.

2. Apply system configurations

$ cd ~/.config/dotnix/
$ ./bin/apply-system.sh

Updating the System Configuration

1. Update dependencies in flake.lock

$ cd ~/.config/dotnix/
$ ./bin/update-system.sh

2. Apply system configurations

$ cd ~/.config/dotnix/
$ ./bin/apply-system.sh

Learn and Do

How I Started

This is the path I took for developing this repo following https://julomeiu.is/tidying-your-home-with-nix/.

1. Install nix

Follow the Zero-to-Nix Quickstart Guide for a flake-compatible nix installation

2. Configure repo Using ~/.config/dotnix instead of ~/.config/nixpkgs

$ mkdir -p ~/.config/dotnix

• Setup up flake.nix and home.nix

• Run nix run .#homeConfigurations.hkailahi.activationPackage to install home-manager and setup first configuration

After this, home-manager switch --flake .#hkailahi can be run to switch home profile (aka rebuild home env via flake.nix and home.nix)

• This is just a shorthand for above nix run .#homeConf....

NOTE: The . in .#hkailahi is the . Since I'm running from dotnix repo, . works, otherwise ~/.config/dotnix or similar prob

Per https://nix-community.github.io/home-manager/index.html#ch-nix-flakes

The flake inputs are not upgraded automatically when switching. The analogy to the command home-manager --update ... is nix flake update.

If updating more than one input is undesirable, the command nix flake lock --update-input can be used.

You can also pass flake-related options such as --recreate-lock-file or --update-input [input] to home-manager when building/switching, and these options will be forwarded to nix build. See the NixOS Wiki page for detail.

Resources

Declarative macOS Configuration - Using nix-darwin And home-manager: https://xyno.space/post/nix-darwin-introduction Setting up Nix on macOS: https://davi.sh/til/nix/nix-macos-setup/