Daniel Duan's Articles About home-manager

Daniel Duan's Articles About home-manager https://duan.ca/tag/home-manager/ Flake For Non-Nix Projects The ideal outcome of using Nix or home-manager is to have as many things as possible under their control. Among these things are developer tools for coding. You may need <code>cargo</code>, and <code>rust-analyzer</code> for Rust projects; <code>ipython</code>, and <code>python-lsp-server</code> for Python projects, etc. Of course, the simplest solution is to have them all installed and configured in home-manager or the OS level. But, over time, you'll end up with a ton of stuff. Maybe that won't bother you. Fine, but this approach is at odds with some convention of the Nix community. You see, there's this command called <code>nix-shell</code>, or <code>nix develop</code>, which sets up a environment with certain packages, with the expectation that you only need them sometimes, usually within the context of developing a certain software project. So, arguably, a better alternative to installing everything you possibly need is to keep only the essential tools you always need, regardless of what you are working on. Things like <code>neovim</code>, <code>git</code>, <code>ripgrep</code>, etc. When a project demands things such as <code>rust-analyzer</code>, running <code>nix develop</code> should set it up for you. How do we implement that? In a imaginary world where every single software project is built with a flake.nix, the <code>devShell</code> property should provide everything the software project owner expect you to need. And you just <code>cd</code> into the root of the project, run <code>nix develop</code>, and you are off to the races. Several problems: <ol> <li>running <code>nix develop</code> is repetitive, and therefore, annoying.</li> <li>the owner of a flake.nix may have drastically different taste for the best dev tools for their project (bet!).</li> <li>we don't live in a world built with Nix flakes.</li> </ol> Yikes. To solve <code>1</code>, enter <a href="https://github.com/nix-community/nix-direnv">direnv</a>. It's a piece of software that let you create a environment for a directory, and automatically switch to it when you enter said directory. The "environment" could contain envvars, and, you guessed it: a Nix developer shell. If you have a flake.nix, add <code>use flake</code> in your project directory's <code>.envrc</code> file, direnv will automatically call <code>nix develop</code> the next time you <code>cd</code> in. Neat! To make this work in practice, you'll want to add <code>.envrc</code> and <code>.direnv/</code> to your global git ignore list, as they are personal preferences that probably shouldn't end up in git history. Ok, we are so close to solve problem <code>2</code>, and <code>3</code> now. In short, <code>nix develop</code> may set up a environment, but it may not be the environment that suits you the best. <a href="https://github.com/nix-community/nix-direnv">nix-direnv</a> extends direnv to save us: <pre><code>use flake path/to/flake#target </code></pre> ... with this in <code>.envrc</code>, direnv will set up the Nix environment according to <code>path/to/flake#target</code>. That could point to any location on your hard drive! You can have a flake.nix whose <code>devShell</code> has <code>cargo</code>, and <code>rust-analyzer</code>. You can have another with <code>ipython</code>, and <code>python-lsp-server</code>. Mix and match to your liking to the infinite degree... For now, I've decided to give nix-direnv a try. Alongside my home-manager configuration, I've also included extra flakes for generic Python/Rust projects, and specific projects that may require a mix of tools. A lot of the project I work on don't use flake as their package manager. With this approach, I get to customize my setup for them each, and stay in the comfort of Nix and home-manager. direnv and nix-direnv can be configured together with home-manager. To achieve everything mentioned in this article, including direnv's shell integration (Fish, for me), it's as simple as <pre><code class="language-Nix"># In home manager config... programs.direnv = { enable = true; nix-direnv = { enable = true; enableFlakes = true; }; } </code></pre> To recap, having the snippet above in my home-manager setup, I now can enter any project's root directory and add a <code>.envrc</code> file with the content <code>use flake ~/src/dotfiles/direnvs/python</code>. <code>~/src/dotfiles/direnvs/python</code> contains a <code>flake.nix</code> (and a <code>flake.lock</code>) that has the <code>devShell</code> value I like for all Python projects. When I <code>cd</code> into this project, <code>(nix-)direnv</code> will read from that <code>devShell</code> and set every tool listed under there. The tools are cached in a <code>.direnv</code> directory so when I return here, the setup is basically instantaneous. Since I make <code>git</code> to ignore <code>.envrc</code>, and <code>.direnv</code> no matter where they are, this project I'm working on is unaffected by all this. Sat, 19 Mar 2022 00:37:01 -0700 https://duan.ca/2022/03/19/nix-dirnev/ https://duan.ca/2022/03/19/nix-dirnev/ Flake, Home Manager, and Extra Packages So, you use a standalone home-manager, it's set up with flake, tracking a particular nixpkgs channel. How do you use a package from another channel? This seemingly simple task took me, a Nix noob, quite a bit of research to solve. Here's how I did it. A simple flake.nix for home-manager might look like this: <pre><code class="language-nix">{ inputs = { nixpkgs.url = "github:nixos/nixpkgs/nixos-21.11"; home-manager.url = "github:nix-community/home-manager/release-21.11"; home-manager.inputs.nixpkgs.follows = "nixpkgs"; }; outputs = { self, nixpkgs, home-manager }: { "dan@some-mac" = home-manager.lib.homeManagerConfiguration { username = "dan"; system = "x86_64-darwin"; homeDirectory = "/home/dan"; configuration = { config, pkgs ... }: { home.packages = [ pkgs.hello ]; }; }; }; } </code></pre> A few things of note: <ol> <li>home manager is set to follow <code>nixpkgs</code>, which tracks <code>nixos-21.11</code>.</li> <li><code>pkgs.hello</code> refers to the package in <code>nixos-21.11</code> as well.</li> </ol> To put things in concrete terms, our goal is to put a package from a channel other than <code>nixos-21.11</code> alongside <code>pkgs.hello</code>. The key to my solution is the <code>extraModules</code> in <code>home-manager.lib.homeManagerConfiguration</code>'s argument set. We'll leverage it to modify the environment made available to its sibling, <code>configuration</code>. First, add the new channel as input <code>nixpkgs-unstable</code>: <pre><code class="language-nix">{ inputs = { # ... nixpkgs-unstable.url = "github:nixos/nixpkgs"; }; ... } </code></pre> Then, add a small module to <code>extraModules</code>. In it we make <code>nixpkgs-unstable</code> an argument to <code>_module</code>. <pre><code class="language-nix">{ input = { ... }; outputs = { self, nixpkgs, nixpkgs-unstable, home-manager }: { # Note we also pass in nixpkgs-unstable here "dan@some-mac" = home-manager.lib.homeManagerConfiguration { extraModules = [ ({ pkgs, ... }: rec { _module.args.nixpkgs-unstable = import nixpkgs-unstable { inherit system; }; }) ]; # ... }; }; } </code></pre> ... now that we added <code>args.nixpkgs-unstable</code>, it becomes available in the configuration: <pre><code class="language-nix">{ input = { ... }; outputs = { self, nixpkgs, nixpkgs-unstable, home-manager }: { # Note we also pass in nixpkgs-unstable here "dan@some-mac" = home-manager.lib.homeManagerConfiguration { # ... configuration = { config, pkgs, nixpkgs-unstable, ... }: home.packages = [ pkgs.hello nixpkgs-unstable.python39Packages.python-lsp-server ]; }; }; }; } </code></pre> There, we made <code>python39Packages.python-lsp-server</code> from nixpkgs's master branch appear alongside our standard, default channel. And that's how you add packages from a different channel in a flake setup for standalone home-manager. Tue, 15 Mar 2022 18:53:59 -0700 https://duan.ca/2022/03/15/standalone-home-manager-flake-channels/ https://duan.ca/2022/03/15/standalone-home-manager-flake-channels/