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athenix/docs/USER_CONFIGURATION.md
2025-12-17 09:25:51 -05:00

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User Configuration Guide

Complete guide to managing user accounts in nixos-systems.

Table of Contents

Overview

Users are defined in users.nix but are not enabled by default on all systems. Each system must explicitly enable users in inventory.nix.

Default enabled users:

  • root - System administrator
  • engr-ugaif - Innovation Factory default account

Quick Start

1. Define User in users.nix

ugaif.users = {
  myuser = {
    description = "My Full Name";
    extraGroups = [ "wheel" "networkmanager" ];
    shell = pkgs.zsh;
    hashedPassword = "$6$...";  # Generate with: mkpasswd -m sha-512
    opensshKeys = [
      "ssh-ed25519 AAAA... user@machine"
    ];
  };
};

2. Enable User on Hosts

In inventory.nix:

nix-laptop = {
  devices = 2;
  overrides.ugaif.users.myuser.enable = true;  # Enables on all nix-laptop hosts
};

# Or for specific devices
nix-desktop = {
  devices = {
    "1".ugaif.users.myuser.enable = true;
    "2".ugaif.users.otheruser.enable = true;
  };
};

# Or use convenience option
nix-wsl = {
  devices."alice".ugaif.forUser = "alice-user";  # Automatically enables user
};

User Account Options

Each user in users.nix can have the following options:

username = {
  # === Identity ===
  description = "Full Name";              # User's full name
  
  # === System Access ===
  isNormalUser = true;                    # Default: true (false for root)
  extraGroups = [                         # Additional Unix groups
    "wheel"                               # Sudo access
    "networkmanager"                      # Network configuration
    "docker"                              # Docker access
    "video"                               # Video device access
    "audio"                               # Audio device access
  ];
  shell = pkgs.zsh;                       # Login shell (default: pkgs.bash)
  hashedPassword = "$6$...";              # Hashed password (see below)
  
  # === SSH Access ===
  opensshKeys = [                         # SSH public keys
    "ssh-ed25519 AAAA... user@host"
    "ssh-rsa AAAA... user@otherhost"
  ];
  
  # === Home Configuration ===
  home = builtins.fetchGit { ... };       # External home-manager config (see below)
  
  # OR (if not using external config):
  homePackages = with pkgs; [             # User packages
    ripgrep
    fd
    bat
  ];
  extraImports = [ ./my-module.nix ];     # Additional home-manager modules
  
  # === Theme Integration ===
  useZshTheme = true;                     # Apply system Zsh theme (default: true)
  useNvimPlugins = true;                  # Apply system Neovim config (default: true)
  
  # === System Enablement ===
  enable = false;                         # Enable on this system (set in inventory.nix)
};

External User Configurations

Users can maintain their dotfiles and home-manager configuration in separate Git repositories.

Basic External Configuration

In users.nix:

myuser = {
  description = "My Name";
  extraGroups = [ "wheel" ];
  hashedPassword = "$6$...";
  
  # Point to external dotfiles repository
  home = builtins.fetchGit {
    url = "https://github.com/username/dotfiles";
    rev = "abc123...";  # Pin to specific commit
  };
};

External Repository Structure

dotfiles/
├── home.nix     # Required: Home-manager configuration
├── nixos.nix    # Optional: System-level configuration
└── config/      # Optional: Your dotfiles
    ├── bashrc
    ├── vimrc
    └── ...

home.nix (required):

{ inputs, ... }:
{ config, lib, pkgs, osConfig, ... }:
{
  home.packages = with pkgs; [ vim git htop ];
  
  programs.git = {
    enable = true;
    userName = "My Name";
    userEmail = "me@example.com";
  };
  
  home.file.".bashrc".source = ./config/bashrc;
}

nixos.nix (optional):

{ inputs, ... }:
{ config, lib, pkgs, ... }:
{
  # System-level configuration
  users.users.myusername.extraGroups = [ "docker" ];
  environment.systemPackages = [ pkgs.docker ];
}

What External Modules Receive

In home.nix:

  • inputs - Flake inputs (nixpkgs, home-manager, etc.)
  • config - Home-manager configuration
  • lib - Nixpkgs library functions
  • pkgs - Package set
  • osConfig - OS-level configuration (read-only)

In nixos.nix:

  • inputs - Flake inputs
  • config - NixOS configuration
  • lib - Nixpkgs library functions
  • pkgs - Package set

Alternative Configuration Methods

Local path (for testing):

home = /home/username/dev/dotfiles;

Inline configuration:

home = {
  home.packages = with pkgs; [ vim ];
  programs.git.enable = true;
};

No external config (legacy):

homePackages = with pkgs; [ vim git ];
# home = null;  # Default

Create User Template

nix flake init -t github:UGA-Innovation-Factory/nixos-systems#user

See templates/user/README.md for complete template.

Enabling Users on Hosts

Users must be explicitly enabled on each host in inventory.nix.

Method 1: Enable in Overrides (All Devices)

nix-laptop = {
  devices = 5;
  overrides = {
    ugaif.users.student.enable = true;  # All 5 laptops get this user
  };
};

Method 2: Enable per Device

nix-desktop = {
  devices = {
    "1".ugaif.users.alice.enable = true;
    "2".ugaif.users.bob.enable = true;
    "3" = {
      ugaif.users.alice.enable = true;
      ugaif.users.bob.enable = true;
    };
  };
};

Method 3: Convenience Option (ugaif.forUser)

Quick setup for single-user systems:

nix-wsl = {
  devices = {
    "alice".ugaif.forUser = "alice-user";  # Automatically enables alice-user
    "bob".ugaif.forUser = "bob-user";
  };
};

This is equivalent to ugaif.users.alice-user.enable = true.

Password Management

Generate Hashed Password

mkpasswd -m sha-512
# Enter password when prompted
# Copy the output hash

In users.nix

myuser = {
  hashedPassword = "$6$rounds=656000$...";  # Paste hash here
};

Disable Password Login

myuser = {
  hashedPassword = "!";  # Locks password, SSH key only
  opensshKeys = [ "ssh-ed25519 ..." ];
};

Change Password Later

On the system:

sudo passwd myuser

Or regenerate hash and update users.nix.

SSH Keys

Adding SSH Keys

myuser = {
  opensshKeys = [
    "ssh-ed25519 AAAAC3Nza... user@laptop"
    "ssh-rsa AAAAB3NzaC1... user@desktop"
  ];
};

Generate SSH Key

ssh-keygen -t ed25519 -C "user@hostname"
cat ~/.ssh/id_ed25519.pub  # Copy this

Multiple Keys

Users can have multiple SSH keys for different machines:

opensshKeys = [
  "ssh-ed25519 ... user@work-laptop"
  "ssh-ed25519 ... user@home-desktop"  
  "ssh-ed25519 ... user@tablet"
];

Examples

Basic User

student = {
  description = "Student Account";
  extraGroups = [ "networkmanager" ];
  shell = pkgs.bash;
  hashedPassword = "$6$...";
};

Admin User with SSH

admin = {
  description = "System Administrator";
  extraGroups = [ "wheel" "networkmanager" "docker" ];
  shell = pkgs.zsh;
  hashedPassword = "$6$...";
  opensshKeys = [
    "ssh-ed25519 AAAA... admin@laptop"
  ];
};

User with External Dotfiles

developer = {
  description = "Developer";
  extraGroups = [ "wheel" "docker" ];
  shell = pkgs.zsh;
  hashedPassword = "$6$...";
  home = builtins.fetchGit {
    url = "https://github.com/username/dotfiles";
    rev = "abc123def456...";
  };
};

WSL User

wsl-user = {
  description = "WSL User";
  extraGroups = [ "wheel" ];
  shell = pkgs.zsh;
  hashedPassword = "$6$...";
  home = builtins.fetchGit {
    url = "https://github.com/username/dotfiles";
    rev = "abc123...";
  };
};

Enable in inventory.nix:

nix-wsl = {
  devices."my-wsl".ugaif.forUser = "wsl-user";
};

User Without System Themes

For users who want complete control over their shell/editor:

poweruser = {
  description = "Power User";
  extraGroups = [ "wheel" ];
  shell = pkgs.zsh;
  hashedPassword = "$6$...";
  useZshTheme = false;      # Don't apply system theme
  useNvimPlugins = false;   # Don't apply system nvim config
  home = builtins.fetchGit {
    url = "https://github.com/username/custom-dotfiles";
    rev = "abc123...";
  };
};

Theme Integration

System Zsh Theme

When useZshTheme = true (default), the system applies:

  • Oh My Posh with custom theme
  • History substring search
  • Vi mode (for non-root users)
  • Zsh plugins (zplug)

Disable if you want full control in your dotfiles.

System Neovim Config

When useNvimPlugins = true (default), the system applies:

  • LazyVim distribution
  • TreeSitter parsers
  • Language servers

Disable if you want to configure Neovim yourself.

Troubleshooting

User Can't Login

Check if enabled on host:

nix eval .#nixosConfigurations.nix-laptop1.config.ugaif.users.myuser.enable

Check if user exists:

# On the system
id myuser

SSH Key Not Working

Check key in configuration:

nix eval .#nixosConfigurations.nix-laptop1.config.users.users.myuser.openssh.authorizedKeys.keys

Verify key format:

  • Should start with ssh-ed25519, ssh-rsa, or ssh-dss
  • Should be all on one line
  • Should end with comment (optional)

External Config Not Loading

Check repository access:

git ls-remote https://github.com/username/dotfiles

Verify structure:

  • Must have home.nix at repository root
  • nixos.nix is optional
  • Check file permissions

Test with local path first:

home = /path/to/local/dotfiles;

See Also