My NixOS Configs

This repo contains a simple nix flake template with NixOS + home-manager.

What this provides

• Minimal version:
  • NixOS configuration on nixos/configuration.nix, accessible via nixos-rebuild --flake .
  • Home-manager configuration on home-manager/home.nix, accessible via home-manager --flake .

Getting started

Assuming you have a basic NixOS booted up (either live or installed, anything works). Here's a link to the latest NixOS downloads, just for you.

The repo

• Download this repo

cd ~
git clone https://github.com/celsomiranda/nix-config
cd nix-config

• Make sure you're running Nix 2.4+, and opt into the experimental flakes and nix-command features:

# Should be 2.4+
nix --version
export NIX_CONFIG="experimental-features = nix-command flakes"

Usage

• Run sudo nixos-rebuild switch --flake .#omen to apply your system configuration.
  • If you're still on a live installation medium, run nixos-install --flake .#omen instead, and reboot.
• Run home-manager switch --flake .#celso@omen to apply your home configuration.
  • If you don't have home-manager installed, try nix shell nixpkgs#home-manager.

And that's it, really! You're ready to have fun with your configurations using the latest and greatest nix3 flake-enabled command UX.

What next?

Adding more hosts or users

You can organize them by hostname and username on nixos and home-manager directories, be sure to also add them to flake.nix.

You can take a look at my (beware, here be reproductible dragons) configuration repo for ideas.

NixOS makes it easy to share common configuration between hosts (you might want to create a common directory for these), while keeping everything in sync. home-manager can help you sync your environment (from editor to WM and everything in between) anywhere you use it. Have fun!

User password and secrets

You have basically two ways of setting up default passwords:

• By default, you'll be prompted for a root password when installing with nixos-install. After you reboot, be sure to add a password to your own account and lock root using sudo passwd -l root.
• Alternatively, you can specify initialPassword for your user. This will give your account a default password, be sure to change it after rebooting! If you do, you should pass --no-root-passwd to nixos-install, to skip setting a password on the root account.

If you don't want to set your password imperatively, you can also use passwordFile for safely and declaratively setting a password from a file outside the nix store.

There's also more advanced options for secret management, including some that can include them (encrypted) into your config repo and/or nix store, be sure to check them out if you're interested.

Dotfile management with home-manager

Besides just adding packages to your environment, home-manager can also manage your dotfiles. I strongly recommend you do, it's awesome!

For full nix goodness, check out the home-manager options with man home-configuration.nix. Using them, you'll be able to fully configure any program with nix syntax and its powerful abstractions.

Alternatively, if you're still not ready to rewrite all your configs to nix syntax, there's home-manager options (such as xdg.configFile) for including files from your config repository into your usual dot directories. Add your existing dotfiles to this repo and try it out!

Try opt-in persistance

You might have noticed that there's impurity in your NixOS system, in the form of configuration files and other cruft your system generates when running. What if you change them in a whim to get something working and forget about it? Boom, your system is not fully reproductible anymore.

You can instead fully delete your / and /home on every boot! Nix is okay with a empty root on boot (all you need is /boot and /nix), and will happily reapply your configurations.

There's two main approaches to this: mount a tmpfs (RAM disk) to /, or (using a filesystem such as btrfs or zfs) mount a blank snapshot and reset it on boot.

For stuff that can't be managed through nix (such as games downloaded from steam, or logs), use impermanence for mounting stuff you to keep to a separate partition/volume (such as /nix/persist or /persist). This makes everything vanish by default, and you can keep track of what you specifically asked to be kept.

Here's some awesome blog posts about it:

• Erase your darlings
• Encrypted BTRFS with Opt-In State on NixOS
• NixOS: tmpfs as root and tmpfs as home
• Paranoid NixOS Setup

Adding custom packages

Something you want to use that's not in nixpkgs yet? You can easily build and iterate on a derivation (package) from this very repository.

Create a folder with the desired name inside pkgs, and add a default.nix file containing a derivation. Be sure to also callPackage them on pkgs/default.nix.

You'll be able to refer to that package from anywhere on your home-manager/nixos configurations, build them with nix build .#package-name, or bring them into your shell with nix shell .#package-name.

See the manual for some tips on how to package stuff.

Adding overlays

Found some outdated package on nixpkgs you need the latest version of? Perhaps you want to apply a patch to fix a behaviour you don't like? Nix makes it easy and manageble with overlays!

Use the overlay/default.nix file for this.

If you're creating patches, you can keep them on the overlay folder as well.

See the wiki article to see how it all works.

Adding your own modules

Got some configurations you want to create an abstraction of? Modules are the answer. These awesome files can expose options and implement configurations based on how the options are set.

Create a file for them on either modules/nixos or modules/home-manager. Be sure to also add them to the listing at modules/nixos/default.nix or modules/home-manager/default.nix.

See the wiki article to learn more about them.

Troubleshooting / FAQ

Please let me know any questions or issues you face with these templates, so I can add more info here!

I'm trying to set nixpkgs.config options (e.g. allowUnfree), but they won't work!

We instantiate nixpkgs and pass it to NixOS, to make the flake a bit simpler and ensure both configs have the same nixpkgs instance, this has the drawback of breaking nixpkgs configuration through in your NixOS config files.

This is a design choice I made based on the homeManagerConfiguration interface, that requires a pkgs instance anyway. If you prefer to set them modularly, you'll have to remove the pkgs argument. If you use overlays, you'll have to pass them into your configuration (through specialArgs) or set nixpkgs.overlays right on the flake; in this case, you might prefer to use home-manager as a NixOS module and set home-manager.useGlobalPkgs = true.

Nix says my repo files don't exist, even though they do!

Nix flakes only see files that git is currently tracked, so just git add . and you should be good to go. Files on .gitignore, of course, are invisible to nix - this is to guarantee your build won't depend on anything that is not on your repo.