A rebuild script that commits on a successful build

configuration.nix

{
  config,
  pkgs,
  options,
  ...
}: let
  hostname = "oatman-pc"; # to alllow per-machine config
in {
  networking.hostName = hostname;

  imports = [
    /etc/nixos/hardware-configuration.nix
    (/home/oatman/dotfiles/nixos + "/${hostname}.nix")
  ];
}

nixos-rebuild.sh

#!/usr/bin/env bash
#
# I believe there are a few ways to do this:
#
#    1. My current way, using a minimal /etc/nixos/configuration.nix that just imports my config from my home directory (see it in the gist)
#    2. Symlinking to your own configuration.nix in your home directory (I think I tried and abandoned this and links made relative paths weird)
#    3. My new favourite way: as @clot27 says, you can provide nixos-rebuild with a path to the config, allowing it to be entirely inside your dotfies, with zero bootstrapping of files required.
#       `nixos-rebuild switch -I nixos-config=path/to/configuration.nix`
#    4. If you uses a flake as your primary config, you can specify a path to `configuration.nix` in it and then `nixos-rebuild switch —flake` path/to/directory
# As I hope was clear from the video, I am new to nixos, and there may be other, better, options, in which case I'd love to know them! (I'll update the gist if so)

# A rebuild script that commits on a successful build
set -e

# Edit your config
$EDITOR configuration.nix

# cd to your config dir
pushd ~/dotfiles/nixos/

# Early return if no changes were detected (thanks @singiamtel!)
if git diff --quiet '*.nix'; then
    echo "No changes detected, exiting."
    popd
    exit 0
fi

# Autoformat your nix files
alejandra . &>/dev/null \
  || ( alejandra . ; echo "formatting failed!" && exit 1)

# Shows your changes
git diff -U0 '*.nix'

echo "NixOS Rebuilding..."

# Rebuild, output simplified errors, log trackebacks
sudo nixos-rebuild switch &>nixos-switch.log || (cat nixos-switch.log | grep --color error && exit 1)

# Get current generation metadata
current=$(nixos-rebuild list-generations | grep current)

# Commit all changes witih the generation metadata
git commit -am "$current"

# Back to where you were
popd

# Notify all OK!
notify-send -e "NixOS Rebuilt OK!" --icon=software-update-available

@aikomastboom love the alejandra tweak - added.

Interesting sudo tweak - but on my machine root using sudo is a no-op and can safely run both normal and sudoed commands?

Yeah, I know.. I came across it when fiddling with a VM that only had root and no sudo installed

I like the idea to nixify the script too ( to ensure those dependency commands are available)

Fellow NixOS noob here thanks to your video! thanks for sharing this script as well.

FYI, I had to surround the two references to '*.nix' in single quotes to prevent bash from expanding the glob which resulted in 'No changes detected' and no diff output. Probably because my configuration is mostly in subfolders.

@MvRens updated, well spotted!

Hi! First of all, great video and an amazing script!
A weird problem i got stuck with is the fact that the nixos-rebuild hashing would not rebuild if the git repo was dirty - this blog post helped but i realized that staging the files fixed it - git add ./*.nix before the rebuild stage.
Aside from that, i found that using sudo nix-env -p /nix/var/nix/profiles/system --list-generations | grep "current" gave a cleaner output then nixos-rebuild list-generations

I added a bit where if a rebuild fails it asks if you want to open the logs or not

# In my case I use flakes but here it checks whether it fails or not
if sudo nixos-rebuild switch --flake ".#$1" &>.nixos-switch.log; then
	echo -e "Done\n"
else
	echo ""
	cat .nixos-switch.log | grep --color error

	# this is needed otherwise the script would not start next time telling you "no changes detected"
	# (The weird patter is to include all subdirectories)
	sudo git restore --staged ./**/*.nix

	if read -p "Open log? (y/N): " confirm && [[ $confirm == [yY] || $confirm == [yY][eE][sS] ]]; then
		cat .nixos-switch.log | vim - 	
	fi

	# Clean stuff and exit
	shopt -u globstar
	popd > /dev/null
	exit 1
fi

thx @0atman for the *hem inspiration ;)

Very cool!

Here's a version that's I edited to work with Home Manager and custom *.nix file locations, I've also added a segment to check for untracked *.nix files since these don't get picked up by git diff
Not sure if ether of those things are useful to anyone else but shrug

Thanks for sharing this script. Now, I won't ruin my system because I messed up my configuration.nix. One improvement that I made when I started using it was to handle the script itself the nix way by storing is a nixos-rebuild.nix file:

{
  config,
  pkgs,
  ...
}: {
  environment.systemPackages = with pkgs; [
    (writeShellScriptBin "nixos-rebuild.sh" ''
    // Script without shebang
        '')
  ];
}

And just importing it in my managed version of configuration.nix. This way, I don't need to think about shebang and my script is also versioned via NixOS using generations too.

Can you link how you've done this? I've imported such a file into my configuration.nix but it's not making the script findable on PATH.

Can you link how you've done this? I've imported such a file into my configuration.nix but it's not making the script findable on PATH.

You need to rebuild the system first use simple nixos-rebuild switch once so script is generated by nix and added to PATH

Yeah all good, got it working shortly afterwards. Added to it with a Home-Manager step as well, very useful script!