nix-configuration/README.md

NixOS Configuration

A full set of configuration files managed via NixOS. This project is an extension of the Auxolotl system template.

Warning

DO NOT DOWNLOAD AND RUN nixos-rebuild ON THIS REPOSITORY! These are my personal configuration files. I invite you to look through them, modify them, and take inspiration from them, but if you run nixos-rebuild, it will completely overwrite your current system!

Using this repo

Note on secrets management

Secrets are stored in a separate repo called nix-secrets, which is included here as a flake input. This is a poor man's secret management solution, but y'know what, it works. These "secrets" will be readable to users on the system with access to the /nix/store/, but for single-user systems, it's fine.

Initialize the submodule with:

git submodule update --init --recursive

First-time installation

To apply the config for the first time (e.g. on a fresh install), run these commands, replacing Shura with the name of the host:

nix flake update
sudo nixos-rebuild switch --flake .#Shura

nix flake update updates the flake.lock file, which pins repositories to specific versions. Nix will then pull down any derivations it needs to meet the version.

Note

This config installs a Nix wrapper called nh. Basic install/upgrade commands can be run using nh, but more advanced stuff should use nixos-rebuild.

Running updates

All hosts are configured to run automatic daily updates (see modules/system/system.nix). You can disable this by adding aux.system.services.autoUpgrade = false; to a hosts config.

Automatic updates work by git pulling the latest version of the Repo from Forgejo. This repo gets updated nightly by Haven, which updates the flake.lock file and pushes it back up to Forgejo. Only one host needs to do this, and you can enable this feature on a host using aux.system.services.autoUpgrade.pushUpdates = true;.

Manually updating

Run nh to update the system. Use the --update flag to update flake.lock as part of the process. Note that for subsequent builds, you can omit the hostname:

nh os boot --update

This is the equivalent of running:

nix flake update
sudo nixos-rebuild boot --flake .

There are a few different actions for handling the update:

• switch replaces the running system immediately.
• boot switches to the new generation during the next reboot.
• build creates and caches the update without applying it.
• test creates the generation and switches to it, but doesn't add it to the bootloader.

Using Remote builds

Nix can create builds for or on remote systems, and transfer them via SSH.

Generating a build on a remote system

You can run a build on a remote server, then pull it down to the local system. This is called a distributedBuild.

Note

For distributed builds, the root user on the local system needs SSH access to the build target. This is done automatically.

To enable root builds on a host, add this to its config:

nix.distributedBuilds = true;

For hosts where nix.distributedBuilds is true, this repo automatically gives the local root user SSH access to an unprivileged user on the build systems. This is configured in nix-secrets, but the build systems are defined in modules/system/nix.nix.

Pushing a build to a remote system

Conversely, you can run a build on the local host, then push it to a remote system.

NIX_SSHOPTS="-o RequestTTY=force" nixos-rebuild --target-host user@example.com --use-remote-sudo switch

Testing without modifying the system

If you want to test without doing a whole build, or without modifying the current system, there are a couple additional tools to try.

Dry builds

To quickly validate your configuration, create a dry build. This analyzes your configuration to determine whether it'll actually build:

nixos-rebuild dry-build --flake .

Virtual machines

You can also build a virtual machine image to preview changes. The first command builds the VM, and the second runs it:

nixos-rebuild build-vm --flake .
./result/bin/run-nixos-vm

Note

Running the VM also creates a .qcow2 file for data persistence. Remove this file after a while, otherwise data might persist between builds and muck things up.

Adding a host

To add a new host:

1. Create a new folder in hosts/.
2. Copy hosts/configuration.nix.template into this folder and name it default.nix.
3. Run nixos-hardware-configuration on the host and copy its hardware-configuration.nix file here. You might also want to check the configuration.nix generated by this command to see if there's anything you should import into your host's default.nix.
4. Configure /hosts/<host>/default.nix however you'd like.
5. Add the new host to flake.nix.
6. Run nix flake update and nixos-rebuild boot --flake .#<Hostname>.

About this repository

Layout

This config uses two main systems: Flakes, and Home-manager.

• Flakes are the entrypoint, via flake.nix. This is where Flake inputs and Flake-specific options get defined.
• Home-manager configs live in the users/ folders.
• Modules are stored in modules. All of these files are automatically imported (except home-manager modules); you simply enable the ones you want to use, and disable the ones you don't. For example, to install Flatpak, set aux.system.ui.flatpak.enable = true;.
  • After adding a new module, make sure to git add it before running nixos-rebuild.

Features

This Nix config features:

• Flakes
• Home Manager
• Automatic daily updates
• AMD, Intel, and Raspberry Pi (ARM64) hardware configurations
• Workstation and server base system configurations
• GNOME desktop environment with KDE integrations
• Boot splash screens via Plymouth
• Secure Boot and TPM
• Disk encryption via LUKS
• Custom packages and systemd services
• Flatpaks
• Default ZSH shell using Oh My ZSH
• Secrets (in a janky hacky kinda way)