Title: Making a home NAS using NixOS

	Title: Making a home NAS using NixOS
	Author: Solène
	Date: 18 October 2020
	Tags: nixos linux nas
	Description:

	Still playing with [NixOS](https://nixos.org/), I wanted to experience
	how difficult it would be to write a NixOS configuration file to
	turn a computer into a simple NAS with basics features: samba
	storage, dlna server and auto suspend/resume.

	What is [NixOS](https://nixos.org/features.html)? As a reminder for
	some and introduction to the others, NixOS is a Linux distribution
	built by the Nix package manager, which make it very different than
	any other operating system out there, except
	[Guix](https://guix.gnu.org/)
	which has a similar approach with their own package manager written
	in Scheme.

	NixOS uses a declarative configuration approach along with lot of
	others features derived from Nix. What's big here is you no longer
	tweak anything in `/etc` or install packages, you can define the
	working state of the system in one configuration file. This system
	is a totally different beast than the others OS and require some
	time to understand how it work. Good news though, everything
	is documented in the man page `configuration.nix`, from fstab
	configuration to users managements or how to enable samba!

	Here is the `/etc/nixos/configuration.nix` file on my NAS.

	It enables ssh server, samba, minidlna and vnstat. Set up a user
	with my ssh public key. Ready to work.

	Using `rtcwake` command (Linux specific), it's possible to put
	the system into standby mode and schedule an auto resume after
	some time. This is triggered by a cron job at 01h00.

	{ config, pkgs, ... }:
	{
	# include stuff related to hardware, auto generated at install
	imports = [ ./hardware-configuration.nix ];
	boot.loader.grub.device = "/dev/sda";

	networking.interfaces.enp3s0.ipv4.addresses = [ {
	address = "192.168.42.150";
	prefixLength = 24;
	} ];
	networking.defaultGateway = "192.168.42.1";
	networking.nameservers = [ "192.168.42.231" ];

	i18n.defaultLocale = "fr_FR.UTF-8";
	console = { font = "Lat2-Terminus16"; keyMap = "fr"; };
	time.timeZone = "Europe/Paris";

	environment.systemPackages = with pkgs; [
	kakoune vnstat borgbackup utillinux
	];

	networking.firewall.enable = false;

	services.openssh.enable = true;
	services.vnstat.enable = true;

	services.cron.systemCronJobs = [
	"0 1 * * * root rtcwake -m mem --date +6h"
	];

	services.samba.enable = true;
	services.samba.enableNmbd = true;
	services.samba.extraConfig = ''
	workgroup = WORKGROUP
	server string = Samba Server
	server role = standalone server
	log file = /var/log/samba/smbd.%m
	max log size = 50
	dns proxy = no
	map to guest = Bad User
	'';
	services.samba.shares = {
	public = {
	path = "/home/public";
	browseable = "yes";
	"writable" = "yes";
	"guest ok" = "yes";
	"public" = "yes";
	"force user" = "share";
	};
	};

	services.minidlna.enable = true;
	services.minidlna.announceInterval = 60;
	services.minidlna.friendlyName = "Rorqual";
	services.minidlna.mediaDirs = ["A,/home/public/Musique/"
	"V,/home/public/Videos/"];

	# note that tmpfiles are not necesserarly temporary if you don't
	# set an expire time. Trick given on irc by someone I forgot the
	name..
	systemd.tmpfiles.rules = [ "d /home/public 0755 share users" ];

	users.users.solene = {
	isNormalUser = true;
	extraGroups = [ "wheel" "sudo" ];
	openssh.authorizedKeys.keys = [
	"ssh-ed25519
	AAAAC3NzaC1lZDI1NTE5AAAAIOIZKLFQXVM15viQXHYRjGqE4LLfvETMkjjgSz0mzMzS
	personal"
	"ssh-ed25519
	AAAAC3NzaC1lZDI1NTE5AAAAIOIZKLFQXVM15vAQXBYRjGqE6L1fvETMkjjgSz0mxMzS
	pro"
	];
	};

	# I prefer a dedicated one than "nobody"
	# can't log into it
	users.users.share= {
	isNormalUser = false;
	};
	}