Title: NixOS review: pros and cons

	Title: NixOS review: pros and cons
	Author: Solène
	Date: 22 January 2021
	Tags: nixos linux
	Description:

	Hello, in this article I would like to share my thoughts about the
	NixOS Linux distribution. I've been using it daily for more than six
	months as my main workstation at work and on some computer at home too.
	I also made modest contributions to the git repository.

	NixOS official website


	## Introduction

	NixOS is a Linux distribution built around Nix tool. I'll try to
	explain quickly what Nix is but if you want more accurate explanations
	I recommend visiting the project website. Nix is the package manager
	of the system, Nix could be used on any Linux distribution on top of
	the distribution package manager. NixOS is built from top to bottom
	from Nix.

	This makes NixOS a system entirely different than what one can expect
	from a regular Linux/Unix system (with the exception of Guix sharing
	the same idea with a different implementation). NixOS system
	configuration is stateless, most of the system is in read-only and most
	of paths you know doesn't exist. The directory /bin/sh only contains
	"sh" which is a symlink.

	The whole system configuration: fstab, packages, users, services,
	crontab, firewall... is configured from a global configuration file
	that defines the state of the system.

	An example of my configuration file to enable graphical interface with
	Mate as a desktop and a french keyboard layout.

	```Code sample for nixos configuration file
	services.xserver.enable = true;
	services.xserver.layout = "fr";
	services.xserver.libinput.enable = true;
	services.xserver.displayManager.lightdm.enable = true;
	services.xserver.desktopManager.mate.enable = true;
	```

	I could add the following lines into the configuration to add auto
	login into my graphical session.

	```Code sample for nixos configuration file
	services.xserver.displayManager.autoLogin.enable = true;
	services.xserver.displayManager.autoLogin.user = "solene";
	```


	## Pros

	There are a lot of pros. The system is really easy to setup,
	installing a system (for a reinstall or replicate an installation) is
	very easy, you only need to get the configuration.nix file from the
	other/previous system. Everything is very fast to setup, it's often
	only a few lines to add to the configuration.

	Every time the system is rebuilt from the configuration file, a new
	grub entry is made so at boot you can choose on which environment you
	want to boot. This make upgrades or tries very easy to rollback and
	safe.

	Documentation! The NixOS documentation is very nice and is part of the
	code. There is a special man page "configuration.nix" in the system
	that contains all variables you can define, what values to expect, what
	is the default and what it's doing. You can literally search for
	"steam", "mediawiki" or "luks" to get information to configure your
	system.

	All the documentation

	Builds are reproducible, I don't consider it a huge advantage but it's
	nice to have it. This allow to challenge a package mirror by building
	packages locally and verifying they provide the exact same package on
	the mirror.

	It has a lot of packages. I think the NixOS team is pretty happy to
	share their statistics because, if I got it right, Nixpkgs is the
	biggest and up to date repository alive.

	Search for a package

	## Cons

	When you download a pre compiled Linux program that isn't statically
	built, it's a huge pain to make it work on NixOS. The binary will
	expect some paths to exist at usual places but they won't exist on
	NixOS. There are some tricks to get them work but it's not always
	easy. If the program you want isn't in the packages, it may not be
	easy to use it. Flatpak can help to get some programs if they are not
	in the packages though.

	Running binaries

	It takes disk space, some libraries can exist at the same time with
	small compilation differences. A program can exist with different
	version at the same time because of previous builds still available for
	boot in grub, if you forget to clean them it takes a lot of memory.

	The whole system (especially for graphical environments) may not feel
	as polished as more mainstream distributions putting a lot of efforts
	into branding and customization. NixOS will only install everything
	and you will have a quite raw environment that you will have to
	configure. It's not a real cons but in comparison to other desktop
	oriented distributions, NixOS may not look as good out of the box.

	## Conclusion

	NixOS is an awesome piece of software. It works very well and I never
	had any reliability issue with it. Some services like xrdp are usually
	quite complex to setup but it worked out of the box here for me.

	I see it as a huge Lego© box with which you can automate the building
	of the super system you want, given you have the schematics of its
	parts. Once you need a block you don't have in your recipes list, you
	will have a hard time.

	I really classify it into its own category, in comparison to Linux/BSD
	distributions and Windows, there is the NixOS / Guix category with
	those stateless systems for which the configuration is their code.