Installing Lazyvim and Oh-My-Zsh on NixOS without Home Manager or flakes

A recent contract I’m on requires me to SSH into a VM running NixOS. Little did I know, its default editor is nano, and besides the repo I’m working on having a VSCode server I could SSH into with Cursor, getting around the filesystem and doing other setup required using nano, which I knew nothing about. I had also lost all my aliases and configs.

Installing neovim

# /etc/nixos/configuration.nix
environment.systemPackages = with pkgs; [
  neovim
];

I decided to install Neovim, and since that worked, why not bring in LazyVim? I was in for a nightmare. As it turns out, Nix is a language, an operating system, and a package manager. Unlike the only other 2 Debian distros I had gently used, there was no apt.

Maybe because Nix is some penultimate meta-operating system where you can configure the hell out of the setup, there are 3+ ways to install any package:

• the authoritative Nix configuration file /etc/nixos/configuration.nix which would install the package globally but require rebuild of the operating system
• the nix-shell -p <package> command which would run it as an ephemeral, isolated bash environment with the package installed for the duration of the shell
• the nix-env command which would install the package globally but has some faction of users who claim you should never use nix-env
• Nix flakes have their own registry, nixpkgs and use the nix run command. They’re also able to be committed to repos and set at the system, user or repo level. As I was on a short timeline and didn’t want to impact the setup of my current project, I decided against this approach.
• other userland inventions like nixvim, kickstart-nix.nvim or home-manager which had their own way of managing the configuration of Neovim.

There are probably more I don’t know about.

Since I had used Nix for all but 2 days, I went down a rabbit hole of old forums and documentation.

As I was using 25.05 NixOS, some of the older posts contained syntax that was no longer valid.

Adding the vimPlugins.LazyVim plugin:

# /etc/nixos/configuration.nix
  environment.systemPackages = with pkgs; [
    ...
    vimPlugins.LazyVim
  ];

Then came the challenge of actually installing my LazyVim config, which I had already saved in my dotfiles, so I cloned, then copied my nvim/.config/nvim into my NixOS /home/user/.config/nvim folder.

Configuring Neovim to use my LazyVim config files:

# /etc/nixos/configuration.nix

programs.neovim = {
  enable = true;
  defaultEditor = true;
  viAlias = true;
  vimAlias = true;
	configure = {
	    customRC = ''

          let mapleader = "\<Space>"

          lua << EOF
            ${builtins.readFile /home/user/.config/nvim/init.lua}

            ${builtins.readFile /home/user/.config/nvim/lua/config/lazy.lua}

            ${builtins.readFile /home/user/.config/nvim/lua/config/keymaps.lua}

            ${builtins.readFile /home/user/.config/nvim/lua/config/autocmds.lua}
          EOF

        '';
	};
 };

And of course, because I’m a demented Mac user, I had to throw in Oh My Zsh for the shell:

# /etc/nixos/configuration.nix

  environment.systemPackages = with pkgs; [
    ...
    oh-my-zsh
  ];

  programs.zsh = {
    enable = true;
    ohMyZsh = {
      enable = true;
      plugins = [ "git" "zsh-autosuggestions" "zsh-autocomplete" "direnv" ];
      theme = "robbyrussell";
    };
  };

Replaced the .zshrc and copied the folders from my custom zsh path at /Users/user/.oh-my-zsh/custom/plugins into NixOS’ /home/user/.oh-my-zsh/custom/plugins.

And now with exec zsh, my auto-completions are back!

The whole config

# /etc/nixos/configuration.nix
{ config, pkgs, ... }:

{
imports = [];

# ...omitted for brevity...

 programs.neovim = {
  enable = true;
  defaultEditor = true;
  viAlias = true;
  vimAlias = true;
	configure = {
	    customRC = ''

          let mapleader = "\<Space>"

          lua << EOF
            ${builtins.readFile /home/jenc/.config/nvim/init.lua}

            ${builtins.readFile /home/jenc/.config/nvim/lua/config/lazy.lua}

            ${builtins.readFile /home/jenc/.config/nvim/lua/config/keymaps.lua}

            ${builtins.readFile /home/jenc/.config/nvim/lua/config/autocmds.lua}
          EOF

        '';
	};
 };

  system.userActivationScripts.zshrc = "touch .zshrc"; # to avoid being prompted to generate the config for the first time

  programs.direnv.enable = true;

 # Enable Zsh with Oh My Zsh
  programs.zsh = {
    enable = true;
    enableCompletion = true;
    ohMyZsh = {
      enable = true;
      plugins = [ "git" "zsh-autosuggestions" "zsh-autocomplete" "direnv" ];
      theme = "robbyrussell";
    };
  };

  # Allow proprietary packages
  nixpkgs.config.allowUnfree = true;

  environment.systemPackages = with pkgs; [
    wget
    direnv
    gitFull
    nixfmt-rfc-style
    starship
    vim
    neovim
    zsh
    oh-my-zsh
    tree
    fzf
    vimPlugins.nvim-cmp
    vimPlugins.LazyVim
];

}

And then nixos-rebuild switch to apply the changes.

If you’re curious, my dotfiles are available on GitHub.