NixOS

For each host (server, laptop, etc.), there is a subdirectory inside hosts.

NixOS installation

For beginners, NixOS can be installed with a graphical installer.

Getting the ISO:

• There is no official torrent as they are not needed due to CDN.
• ISO and checksum are available here: https://nixos.org/download#nixos-iso
• There are unofficial torrents. If the checksum is compared with the one from the official website, these can be used as well: https://github.com/AnimMouse/NixOS-ISO-Torrents/releases

During installation, select manual partitioning:

• One 512MB (or larger) Fat32 partition, mounted at /boot, "boot" flag enabled
• Another partition (e.g. BTRFS) covering the rest of the drive, mounted at /, encryption enabled

Update, build and switch

Update

• Updating NixOS. https://superuser.com/a/1604695

Update channel and configuration:

sudo nix-channel --update && niv update

To apply the updates, continue with "Build and switch".

Build and switch

• https://nixos.wiki/wiki/Nixos-rebuild
• https://discourse.nixos.org/t/how-to-get-this-pending-updates-notification-in-gnome/16344/3
• https://discourse.nixos.org/t/how-to-get-this-pending-updates-notification-in-gnome/16344/6

Option I: Build config and view changes:

# This leaves a symlink named `result` in the current directory.
sudo nixos-rebuild -I nixos-config=hosts/$(hostname)/configuration.nix build
nix --extra-experimental-features nix-command store diff-closures /run/current-system ./result
#=> ...
#=> linux: 6.1.47, 6.1.47-modules → 6.1.51, 6.1.51-modules, -11.8 KiB

Depending on if there are large kernel changes, either switch to it directly or wait until next boot:

sudo ./result/bin/switch-to-configuration switch
# or
# TODO: This does not work. There is no new boot menu entry :/
sudo ./result/bin/switch-to-configuration boot

Option II: Build new config and activate it:

sudo nixos-rebuild -I nixos-config=hosts/$(hostname)/configuration.nix switch

Option III: Build new config and activate it during next boot:

sudo nixos-rebuild -I nixos-config=hosts/$(hostname)/configuration.nix boot

Failed services

If there are e.g. file conflicts due to preexisting dotfiles, the Home Manager user service might fail. To list all failed services, run:

systemctl --failed

Garbage collection

• https://nixos.org/manual/nix/stable/package-management/garbage-collection.html
• https://discourse.nixos.org/t/why-doesnt-nix-collect-garbage-remove-old-generations-from-efi-menu/17592/4

For all profiles:

sudo nix-collect-garbage --delete-older-than 14d

Remove old generations from EFI:

sudo /run/current-system/bin/switch-to-configuration boot

Install Home Manager with niv

niv:

Easy dependency management for Nix projects.

Nix is a very powerful tool for building code and setting up environments. niv complements it by making it easy to describe and update remote dependencies (URLs, GitHub repos, etc). It is a simple, practical alternative to Nix flakes.

https://github.com/nmattia/niv

Niv is an easy dependency management for Nix projects with package pinning.

https://github.com/mikeroyal/NixOS-Guide

Home Manager:

[Home Manager] allows declarative configuration of user specific (non-global) packages and dotfiles.

To avoid breaking users' configurations, Home Manager is released in branches corresponding to NixOS releases ( e.g. release-23.05).

Home Manager provides both the channel-based setup and the flake-based one.

https://github.com/nix-community/home-manager

Check your channel:

sudo nix-channel --list
#=> nixos https://nixos.org/channels/nixos-23.05

Use the corresponding branch:

niv add nix-community/home-manager -n home-manager -b release-23.05

disko and nixos-anywhere

• Introductory presentation: https://pad.lassul.us/cccamp-workshop
• disko: https://github.com/nix-community/disko
• nixos-anywhere: https://github.com/numtide/nixos-anywhere/

# TODO (!)

BTRFS Swap file

• https://nixos.wiki/wiki/Btrfs#Swap_file
• https://wiki.archlinux.org/title/btrfs#Swap_file

Summary:

• Create subvolume @swap directly below top-level subvolume.
• Mount at /swap
• Create swapfile: sudo btrfs filesystem mkswapfile --size 8g --uuid clear /swap/swapfile
• Regenerate hardware-configuration: sudo nixos-generate-config --dir hosts/$(hostname)
• Add swapDevices = [ { device = "/swap/swapfile"; } ]; to hardware configuration and run nixos-rebuild switch (see above).

Automount encrypted drive

• Generate and add keyfile to LUKS device
• luksOpen and mount drive, e.g. to /mnt/data1
• Re-generate hardware configuration:

sudo nixos-generate-config --dir hosts/$(hostname)

GNOME extensions

• https://github.com/nix-community/home-manager/issues/284#issuecomment-531384656
• https://github.com/nix-community/home-manager/issues/284#issuecomment-1321199263
  • Search for packaged extensions: https://search.nixos.org/packages?channel=23.05&from=0&size=50&sort=relevance&type=packages&query=gnomeExtensions
  • One has to re-login after changes: https://github.com/nix-community/home-manager/issues/284#issuecomment-1328269433

# TODO

Run an AppImage

• https://nixos.wiki/wiki/Appimage

# Note how your shell prefix changes.
nix-shell --packages appimage-run

# Inside the shell, you can run an AppImage:
appimage-run ~/Downloads/ubports-installer_0.10.0_linux_x86_64.AppImage

System information

nix-info -m

 - system: `"x86_64-linux"`
 - host os: `Linux 6.1.51, NixOS, 23.05 (Stoat), 23.05.3242.da5adce0ffaf`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.13.5`
 - channels(root): `"nixos-23.05"`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixos`

General Notes

• There is controversy about flakes, rather use channels (e.g. with niv)
• Prins, P., Suresh, J. and Dolstra, E., "Nix fixes dependency hell on all Linux distributions," Archived December 26, 2008, at the Wayback Machine linux.com, December 22, 2008

Nix Pills

• https://nixos.org/guides/nix-pills/pr01

It provides a tutorial introduction into the Nix package manager and Nixpkgs package collection, in the form of short chapters called 'pills'.

Papers

Papers about Nix:

• The Purely Functional Software Deployment Model (2006). http://nixos.org/~eelco/pubs/phd-thesis.pdf, https://edolstra.github.io/pubs/phd-thesis.pdf, https://github.com/edolstra/edolstra.github.io/blob/master/pubs/phd-thesis.pdf
  • May 2023: Some insights from the thesis in short form. https://jonathanlorimer.dev/posts/nix-thesis.html
• NixOS: A Purely Functional Linux Distribution (2008): https://github.com/edolstra/edolstra.github.io/blob/master/pubs/nixos-icfp2008-final.pdf, https://github.com/edolstra/edolstra.github.io/blob/master/pubs/nixos-jfp-final.pdf
• Nix: A Safe and Policy-Free System for Software Deployment (2004): https://edolstra.github.io/pubs/nspfssd-lisa2004-final.pdf

Search for packages

• https://search.nixos.org/packages?channel=23.05

Search for options

• https://search.nixos.org/options?channel=23.05
  • Or man configuration.nix
• https://mipmip.github.io/home-manager-option-search
  • Or man home-configuration.nix

Search wich package owns a file

# Note how your shell prefix changes.
nix-shell --packages nix-index

# Either build the index manually (requires >12GB RAM):
nix-index
# Or download weekly build:
mkdir -p ~/.cache/nix-index/ && wget -q -N https://github.com/nix-community/nix-index-database/releases/latest/download/index-x86_64-linux -O ~/.cache/nix-index/files

# Then search for a file
nix-locate -w '/bash'

List files of package

• https://discourse.nixos.org/t/list-files-of-package/25830/2?u=langfingaz

Example for nano:

find $(nix-build '<nixpkgs>' -A nano --no-link)

Excerpt of the result:

/nix/store/jqvxmx65mfinbsm6db9kmcqmphl44xhp-nano-7.2/share/nano
/nix/store/jqvxmx65mfinbsm6db9kmcqmphl44xhp-nano-7.2/share/nano/asm.nanorc
/nix/store/jqvxmx65mfinbsm6db9kmcqmphl44xhp-nano-7.2/share/nano/autoconf.nanorc

Compare two versions of NixOS system profile

nix --extra-experimental-features nix-command store diff-closures /nix/var/nix/profiles/system-110-link /nix/var/nix/profiles/system-116-link

cpupower: 6.1.47 → 6.1.51
element-desktop: 1.11.38 → 1.11.40, +2218.9 KiB
element-web: 1.11.38 → 1.11.40, -73.1 KiB
exempi: 2.6.3 → 2.6.4
firefox: 116.0.3 → 117.0
firefox-unwrapped: 116.0.3 → 117.0, -292.6 KiB
gnome-shell-extension-openweather: ∅ → 121, +590.5 KiB
hm_fontconfigconf.d10hmfonts.conf: ∅ → ε
initrd: ∅ → ε
initrd-linux: 6.1.47 → 6.1.51
libcap: 2.68 → 2.69
linux: 6.1.47, 6.1.47-modules → 6.1.51, 6.1.51-modules, -11.8 KiB
meld: ∅ → 3.22.0, +3858.5 KiB
net-snmp: 5.9.3 → 5.9.4
nixos-system-yodaTab: 23.05.3085.2ab91c8d65c0 → 23.05.3242.da5adce0ffaf
openjdk: +19.5 KiB
python3.10-pygobject: +27.0 KiB
stage: ∅ → 1-init.sh, +29.5 KiB
tor-browser-bundle-bin: 12.5.2 → 12.5.3, +18.1 KiB
user: +2885.0 KiB

NixOS configuration debugging

• https://nixos.wiki/wiki/Nix_command/repl

Evaluating parts of the configuration.

First, start nix repl:

nix repl --file '<nixpkgs/nixos>' -I nixos-config=hosts/$(hostname)/configuration.nix

Example: config.home-manager

config.home-manager.
# Press `TAB`
#=> config.home-manager.backupFileExtension  config.home-manager.useUserPackages
#=> config.home-manager.extraSpecialArgs     config.home-manager.users
#=> config.home-manager.sharedModules        config.home-manager.verbose
#=> config.home-manager.useGlobalPkgs

Example: The home variable:

config.home-manager.users.yoda.home

Example: The value of one config option

# The following option is set to `"${config.xdg.dataHome}/.histfile";`
# where `config` is the Home Manager configuration.

config.home-manager.users.yoda.programs.zsh.history.path
#=> "/home/yoda/.local/share/.histfile"

Evaluate NixOS configuration to JSON

See also section "NixOS Configuration Debugging"!

TODO: https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-show-config.html

• https://discourse.nixos.org/t/can-i-run-nix-instantiate-eval-strict-on-my-configuration-nix/7105/4

This evaluates configuration.nix (single module):

NIXPKGS_ALLOW_UNFREE=1 nix-instantiate --strict --json --eval -E '
import ./hosts/yodaTab/configuration.nix  {
  config = {};
  pkgs = import <nixpkgs> {};
  lib = import <nixpkgs/lib>;
}
' > evaluated-config.json

Then open evaluated-config.json.

References

Some references to websites that helped me create this repository:

• https://github.com/Misterio77/nix-starter-configs
• https://github.com/mikeroyal/NixOS-Guide#getting-started

TODOs

• FDE remote SSH unlock: https://nixos.wiki/wiki/Remote_LUKS_Unlocking, https://wiki.archlinux.org/title/Dm-crypt/Specialties#Remote_unlocking_of_root_(or_other)_partition
• Yubikey FDE: https://github.com/georgewhewell/nixos-host/blob/master/profiles/luks-yubi.nix
• Impermanence, opt-in to persistence: https://github.com/Misterio77/nix-starter-configs/tree/main#try-opt-in-persistance
• nix-shell / lorri
  • https://ghedam.at/15978/an-introduction-to-nix-shell
    • docker-compose.yml for services and nix-shell to run the code