--- title: "Nix Flakes on WSL" date: 2022-05-04 series: nix-flakes tags: - nixos - wsl vod: youtube: https://youtu.be/VzQ_NwFJObc twitch: https://www.twitch.tv/videos/1464781566 --- About five years ago, Microsoft released the Windows Subsystem for Linux ([WSL](https://docs.microsoft.com/en-us/windows/wsl/)). This allows you to run Linux programs on a Windows machine. When they released WSL version 2 in 2019, this added support for things like Docker and systemd. As a result, this is enough to run NixOS on Windows. This will give you an environment to run Nix and Nix Flakes commands with. You can use this to follow along with this series without having to install NixOS on a VM or cloud server. ## Installation Head to the NixOS-WSL [releases page](https://github.com/nix-community/NixOS-WSL/releases/) and download the `nixos-wsl-installer-fixed.tar.gz` file to your Downloads folder. Then open Powershell and make a folder called `WSL`: ```powershell New-Item -Path .\WSL -ItemType Directory ``` It's worth noting that Powershell does have a bunch of aliases for common coreutils commands to the appropriate Powershell CMDlets. However these aliases are NOT flag-compatible and use the Powershell semantics instead of the semantics of the command it is aliasing. This will bite you when you use commands like wget out of instinct to download things. In order to avoid your muscle memory betraying you, the Powershell CMDlets are shown here in their full overly verbose glory. Then enter the directory with `Set-Location`: ```powershell Set-Location -Path .\WSL ``` This directory is where the NixOS root filesystem will live. If you want to put this somewhere else, feel free to. Somewhere in `%APPDATA%` will work, just as long as it's on an NTFS volume somewhere. Make a folder for the NixOS filesystem: ```powershell New-Item -Path .\NixOS -ItemType Directory ``` Then install the NixOS root image with the `wsl` command: ```powershell wsl --import NixOS .\NixOS\ ..\Downloads\nixos-wsl-installer-fixed.tar.gz --version 2 ``` And start NixOS once to have it install itself: ```powershell wsl -d NixOS ``` Once that finishes, press control-D (or use the `exit` command) to exit out of NixOS and restart the WSL virtual machine: ```powershell exit wsl --shutdown wsl -d NixOS ``` And then you have yourself a working NixOS environment! It's very barebones, but we can use it to test the `nix run` command against our gohello command: ```console $ nix run github:Xe/gohello Hello reader! ``` ## Local Services We can also use this NixOS environment to run a local nginx server. Open `/etc/nixos/configuration.nix`: ```nix { lib, pkgs, config, modulesPath, ... }: with lib; let nixos-wsl = import ./nixos-wsl; in { imports = [ "${modulesPath}/profiles/minimal.nix" nixos-wsl.nixosModules.wsl ]; wsl = { enable = true; automountPath = "/mnt"; defaultUser = "nixos"; startMenuLaunchers = true; # Enable integration with Docker Desktop (needs to be installed) # docker.enable = true; }; # Enable nix flakes nix.package = pkgs.nixFlakes; nix.extraOptions = '' experimental-features = nix-command flakes ''; } ``` Right after the `wsl` block, add this nginx configuration to the file: ```nix services.nginx.enable = true; services.nginx.virtualHosts."test.local.cetacean.club" = { root = "/srv/http/test.local.cetacean.club"; }; ``` This will create an nginx configuration that points the domain `test.local.cetacean.club` to the contents of the folder `/srv/http/test.local.cetacean.club`. The /srv folder is set aside for site-specific data, which is code for "do whatever you want with this folder". In many cases people make a separate /srv/http folder and put each static subdomain in its own folder under that, however I am also told that it is idiomatic to put stuff in /var/www. Pick your poison. Then you can test the web server with the `curl` command: ```console $ curl http://test.local.cetacean.club 404 Not Found

404 Not Found


nginx
``` This is good! Nginx is running and since we haven't created the folder with our website content yet, this 404 means that it can't find it! Let's create the folder so that nginx has permission to it and we can modify things in it: ``` sudo mkdir -p /srv/http/test.local.cetacean.club sudo chown nixos:nginx /srv/http/test.local.cetacean.club ``` Finally we can make an amazing website. Open `/srv/http/test.local.cetacean.club/index.html` in nano: ``` nano /srv/http/test.local.cetacean.club/index.html ``` And paste in this HTML: ```html amazing website xD

look at my COOL WEBsite :3/h1> idk It's pretty random tbh, like me!! <3 :D ``` And then you can see it show up with `curl`: ```console $ curl http://test.local.cetacean.club amazing website xD

look at my COOL WEBsite :3/h1> idk It's pretty random tbh, like me!! <3 :D ``` You can also check this out in a browser by clicking [here](http://test.local.cetacean.club): ![a browser window titled "amazing website xD" with the header "look at my COOL WEBsite" and content of "idk It's pretty random tbh, like me!! <3 :D"](https://cdn.christine.website/file/christine-static/blog/Screenshot+2022-04-23+141937.png) ## Installing `gohello` To install the `gohello` service, first we will need to convert this machine to use NixOS flakes. We can do that really quick and easy by adding this file to `/etc/nixos/flake.nix`: Do this as root! ```nix { inputs = { nixpkgs.url = "nixpkgs/nixos-unstable"; }; outputs = { self, nixpkgs, ... }: { nixosConfigurations.nixos = nixpkgs.lib.nixosSystem { system = "x86_64-linux"; modules = [ ./configuration.nix # add things here ]; }; }; } ``` Then run `nix flake check` to make sure everything is okay: ``` sudo nix flake check /etc/nixos ``` And finally activate the new configuration with flakes: ``` sudo nixos-rebuild switch ``` After it thinks for a bit, you should notice that nothing happened. This is good, we have just converted the system over to using Nix flakes instead of the classic `nix-channel` rebuild method. To get `gohello` in the system, first we need to add `git` to the commands available on the system in `configuration.nix`: ```nix environment.systemPackages = with pkgs; [ git ]; ``` Then we can add `gohello` to our system flake: ```nix { inputs = { nixpkgs.url = "nixpkgs/nixos-unstable"; # XXX(Xe): this URL may change for you, such as github:Xe/gohello-http gohello.url = "git+https://tulpa.dev/cadey/gohello-http?ref=main"; }; outputs = { self, nixpkgs, gohello, ... }: { nixosConfigurations.nixos = nixpkgs.lib.nixosSystem { system = "x86_64-linux"; modules = [ ./configuration.nix # add things here gohello.nixosModule ({ pkgs, ... }: { xeserv.services.gohello.enable = true; }) ]; }; }; } ``` And rebuild the system with `gohello` enabled: ``` sudo nixos-rebuild switch ``` Finally, poke it with `curl`: ```console $ curl http://gohello.local.cetacean.club hello world :) ``` To update it, update the flake inputs in `/etc/nixos` and run `nixos-rebuild`: ``` sudo nix flake update /etc/nixos sudo nixos-rebuild switch ``` --- And from here you can do whatever you want with NixOS. You can use [containers](https://nixos.org/manual/nixos/stable/#ch-containers), set up arbitrary services, or plan for world domination as normal. I thought it was "to save the world from devastation", not "to plan for world domination". Who needs a monopoly on violence for world domination when you have Nix expressions? Siiiiiiiiiiiiiiiiiigh. I will use this setup in future posts to make this more accessible and easy to hack at without having to have a dedicated NixOS machine laying around.