NixOS Configuration ❄

A (WIP) NixOS Configuration repo for all my systems.

New Installation Guide

NixOS

First, install a minimal installation of NixOS.

Next, once you get into the system. Create a new entry for the system in the nixosConfigurations. This will require copying the hardware-configuration.nix file into the config as well. Be sure to also go through the configuration.nix and set the relevent parameters to build the same system.

Enable flakes on the original system. Add the following to the /etc/nixos/configuration.nix file.

nix.settings.experimental-features = [ "nix-command" "flakes" ];
environment.systemPackages = with pkgs; [ git ];

Make sure to update the channels to unstable as well.

nix-channel --add https://nixos.org/channels/nixos-unstable nixos
nixos-rebuild switch --upgrade

Other Linux Distros and Mac

Since the external linux system is managing the system software, we use nix to manage the user software. Once the software has been installed, things may not work as expected. This is because some user-level software needs to talk to system software and with nix not managing that software anymore there is a disconnect. You have to manually configure the host system to properly integrate with nix. Look at the subsections for further details on what worked on.

Use the following for the first time install (since home-manager is not present in an environment yet). It uses home manager from github to bootstrap the installation.

nix run github:nix-community/home-manager -- switch --flake .#generic-linux

Fedora

I had to disable the following services/sockets and reboot my system.

sudo systemctl stop pcscd.service
sudo systemctl stop pcscd.socket
sudo systemctl disable pcscd.service
sudo systemctl disable pcscd.socket

systemctl --user stop gcr-ssh-agent.service
systemctl --user stop gcr-ssh-agent.socket
systemctl --user disable gcr-ssh-agent.service
systemctl --user disable gcr-ssh-agent.socket
systemctl --user mask gcr-ssh-agent.service
systemctl --user mask gcr-ssh-agent.socket

This will break any other programs that want to use smartcards through Fedora. I don't have any other uses I think. It also disables support for the gnome keyring for ssh but that is also fine for me.

Basic Usage

NixOS

Install the nixos system. Note this command is hardware dependent. We use the hostname to associate hardware.

sudo nixos-rebuild switch --flake .#${hostname}

If nh is availabe on the system, you can simply do

nh os switch .

Other Linux Distros and Mac

All future invocations in the environment should have home-manager present.

home-manager switch --flake .#generic-linux

Directory Structure

The following directory stores my home-manager configurations. They are sorted into their respective tools, cli and desktop.

home/
  amlesh.nix
  cli/
    default.nix
    git.nix
    kakoune.nix
    ...
  desktop/
    default.nix
    alacritty.nix
    herbstluftwm.nix
    ...

Every machine has its own directory. NixOS machines have configuration.nix and hardware-configuration.nix. Non-NixOS machines only have home.nix.

Most hosts use the default home-manager configuration from home/amlesh.nix.

hosts/
  solaris/
    configuration.nix
    hardware-configuration.nix
  xynthar/
    configuration.nix
    hardware-configuration.nix
  yggdrasil/
    configuration.nix
    hardware-configuration.nix
    services/
      kavita.nix
  alexandria/
    configuration.nix
    hardware-configuration.nix
  generic-linux/
    home.nix

All NixOS system level configurations

nixos/
  audio.nix
  security.nix
  nix.nix
  ...

Shared library code used across configurations

lib/
  constants.nix
  colorschemes.nix

Development environment templates

templates/
  python312.nix
  rust.nix

Development

For basic development testing, run the following command to test.

nix develop --command test

You can run the testing and linting functions directly with

nix build .#checks.x86_64-linux.nixfmt
nix build .#checks.x86_64-linux.statix
nix build .#checks.x86_64-linux.deadnix

Troubleshooting

Inspecting Configuration Attributes

To inspect what attributes your system configuration is resolving to:

# Inspect a specific attribute from your NixOS configuration
nix eval .#nixosConfigurations.solaris.config.system.stateVersion

# Inspect custom options like fontScale
nix eval .#nixosConfigurations.solaris.config.home-manager.users.amlesh.my.fontScale

# See all available options for a configuration
nix eval .#nixosConfigurations.solaris.options --apply builtins.attrNames

# Inspect a home-manager attribute
nix eval .#homeConfigurations.generic-linux.config.home.stateVersion

Checking What Will Change

Before applying changes, see what will be rebuilt:

# For NixOS systems - dry run to see what changes
nixos-rebuild dry-build --flake .#solaris

# Show differences between current and new configuration
nixos-rebuild build --flake .#solaris
nix store diff-closures /run/current-system ./result

# For home-manager
home-manager build --flake .#generic-linux
nix store diff-closures ~/.local/state/home-manager/gcroots/current-home ./result

Common Issues

Flake evaluation errors:

# Show detailed trace for debugging
nix flake check --show-trace

# Validate flake structure
nix flake metadata

Misc

Refer to this for neovim configuration reference

• https://github.com/zamlz/nix/blob/007d7ffa9c244af4d539fa7b32e8cb2a76ae4d91/shell/neovim.nix

Useful configs to take a look at:

• https://github.com/kaleocheng/nix-dots/tree/master `