# Why I threw out my dotfiles

2021-09-08 by Dave Gallant
nix dotfiles home‑manager

Over the years I have collected a number of dotfiles that I have shared across both Linux and macOS machines (`~/.zshrc`, `~/.config/git/config`, `~/.config/tmux/tmux.conf`, etc). I have tried several different ways to manage them, including bare git repos and utilities such as GNU Stow. These solutions work well enough, but I have since found what I would consider a much better solution for organizing user configuration: home-manager.

## What is home-manager?#

Before understanding home-manager, it is worth briefly discussing what nix is. nix is a package manager that originally spawned from a PhD thesis. Unlike other package managers, it uses symbolic links to keep track of the currently installed packages, keeping around the old ones in case you may want to rollback.

For example, I have used nix to install the package bind which includes `dig`. You can see that it is available on multiple platforms. The absolute path of `dig` can be found by running:

    $ ls -lh $(which dig)
    lrwxr-xr-x 73 root 31 Dec  1969 /run/current-system/sw/bin/dig -> /nix/store/0r4qdyprljd3dki57jn6c6a8dh2rbg9g-bind-9.16.16-dnsutils/bin/dig

Notice that there is a hash included in the file path? This is a nix store path and is computed by the nix package manager. This nix pill does a good job explaining how this hash is computed. All of the nix pills are worth a read, if you are interested in learning more about nix itself. However, using home-manager does not require extensive knowledge of nix.

Part of the nix ecosystem includes nixpkgs. Many popular tools can be found already packaged in this repository. As you can see with these stats, there is a large number of existing packages that are being maintained by the community. Contributing a new package is easy, and anyone can do it!

home-manager leverages the nix package manager (and nixpkgs), as well the nix language so that you can declaratively define your system configuration. I store my nix-config in git so that I can keep track of my packages and configurations, and retain a clean and informative git commit history so that I can understand what changed and why.

## Setting up home-manager#

> ⚠️ If you run this on your main machine, make sure you backup your configuration files first. home-manager is pretty good about not overwriting existing configuration, but it is better to have a backup! Alternatively, you could test this out on a VM or cloud instance.

The first thing you should do is install nix:

    curl -L https://nixos.org/nix/install | sh

It’s generally not a good idea to curl and execute files from the internet (without verifying integrity), so you might want to download the install script first and take a look before executing it!

Open up a new shell in your terminal and running `nix` should work. If not, run `. ~/.nix-profile/etc/profile.d/nix.sh`

Now, install home-manager:

    nix-channel --add https://github.com/nix-community/home-manager/archive/master.tar.gz home-manager
    nix-channel --update
    nix-shell '<home-manager>' -A install

You should see a wave of `/nix/store/*` paths being displayed on your screen.

Now, to start off with a basic configuration, open up `~/.config/nixpkgs/home.nix` in the editor of your choice and paste this in (you will want to change `userName` and `homeDirectory`):

    { config, pkgs, ... }:

    {
      programs.home-manager.enable = true;

      home = {
        username = "dave";
        homeDirectory = "/home/dave";
        stateVersion = "21.11";
        packages = with pkgs; [
          bind
          exa
          fd
          ripgrep
        ];
      };

      programs = {

        git = {
          enable = true;
          aliases = {
            aa = "add -A .";
            br = "branch";
            c = "commit -S";
            ca = "commit -S --amend";
            cb = "checkout -b";
            co = "checkout";
            d = "diff";
            l =
              "log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit";
          };

          delta = {
            enable = true;

            options = {
              features = "line-numbers decorations";
              whitespace-error-style = "22 reverse";
              plus-style = "green bold ul '#198214'";
              decorations = {
                commit-decoration-style = "bold yellow box ul";
                file-style = "bold yellow ul";
                file-decoration-style = "none";
              };
            };
          };

          extraConfig = {
            push = { default = "current"; };
            pull = { rebase = true; };
          };

        };

        starship = {
          enable = true;
          enableZshIntegration = true;

          settings = {
            add_newline = false;
            scan_timeout = 10;
          };
        };

        zsh = {
          enable = true;
          enableAutosuggestions = true;
          enableSyntaxHighlighting = true;
          history.size = 1000000;

          localVariables = {
            CASE_SENSITIVE = "true";
            DISABLE_UNTRACKED_FILES_DIRTY = "true";
            RPROMPT = ""; # override because macOS defaults to filepath
            ZSH_AUTOSUGGEST_HIGHLIGHT_STYLE = "fg=#838383,underline";
            ZSH_DISABLE_COMPFIX = "true";
          };

          initExtra = ''
            export PAGER=less
          '';

          shellAliases = {
            ".." = "cd ..";
            grep = "rg --smart-case";
            ls = "exa -la --git";
          };

          "oh-my-zsh" = {
            enable = true;
            plugins = [
              "gitfast"
              "last-working-dir"
            ];
          };

        };

      };
    }

Save the file and run:

    home-manager switch

You should see another wave of `/nix/store/*` paths. The new configuration should now be active.

If you run `zsh`, you should see that you have starship and access to several other utils such as `rg`, `fd`, and `exa`.

This basic configuration above is also defining your `~/.config/git/config` and `.zshrc`. If you already have either of these files, home-manager will complain about them already existing.

If you run `cat ~/.zshrc`, you will see the way these configuration files are generated.

You can extend this configuration for programs such as (neo)vim, emacs, alacritty, ssh, etc. To see other programs, take a look at home-manager/modules/programs.

## Gateway To Nix#

In ways, home-manager can be seen as a gateway to the nix ecosystem. If you have enjoyed the way you can declare user configuration with home-manager, you may be interested in expanding your configuration to include other system dependencies and configuration. For example, in Linux you can define your entire system’s configuration (including the kernel, kernel modules, networking, filesystems, etc) in nix. For macOS, there is nix-darwin that includes nix modules for configuring launchd, dock, and other preferences and services. You may also want to check out Nix Flakes: a more recent feature that allows you declare dependencies, and have them automatically pinned and hashed in `flake.lock`, similar to that of many modern package managers.

## Wrapping up#

The title of this post is slightly misleading, since it’s possible to retain some of your dotfiles and have them intermingle with home-manager by including them alongside nix. The idea of defining user configuration using nix can provide a clean way to maintain your configuration, and allow it to be portable across platforms. Is it worth the effort to migrate away from shell scripts and dotfiles? I’d say so.

You can find my nix config here.