nixos-config

Installation Guide

This guide explains how to install my NixOS configuration.

Quick Start

Configure my system by editing install-config.nix
Boot from NixOS Live USB
Clone this repository
Run the installer

Configuration

Edit install-config.nix at the root of this repository:

{
  # Disk configuration
  disk = {
    # Device to use (null = auto-detect first disk during installation)
    # Set to specific device if needed, e.g., "/dev/nvme0n1"
    device = null;

    # Filesystem type: "btrfs" or "ext4"
    filesystem = "btrfs";

    # Enable LUKS encryption (true/false)
    useLuks = true;

    # Partition sizes
    swapSize = "32G";      # Swap partition size
    efiSize = "512M";      # EFI partition size

    # Encryption settings (only used if useLuks = true)
    luks = {
      name = "crypted";    # Name for the encrypted volume
    };
  };

  # Btrfs settings (only used if filesystem = "btrfs")
  btrfs = {
    filesystemLabel = "nixos";
    subvolumes = {
      "/" = { };
      "/home" = {
        compression = "zstd";
      };
      "/nix" = {
        options = [ "noatime" "compress-force=zstd:1" "nodatacow" ];
      };
      "/var/log" = {
        compression = "zstd";
      };
    };
  };

  # Ext4 settings (only used if filesystem = "ext4")
  ext4 = {
    filesystemLabel = "nixos";
    mountOptions = [ "noatime" ];
  };

  # Tmpfs configuration
  tmpfs = {
    enable = true;
    size = "4G";
    mode = "1777";
  };
}

Note: The hostname should be set in hosts/<your-host>/default.nix, NOT in install-config.nix.

Common configurations:

For no encryption: useLuks = false;
For ext4 filesystem: filesystem = "ext4";
For different swap size: swapSize = "16G";

Installation Steps

1. Boot from NixOS Live USB

Download and flash the latest NixOS minimal ISO:

# Download NixOS ISO
wget https://channels.nixos.org/latest-nixos-minimal-x86_64-linux.iso

# Flash to USB (replace /dev/sdX with your USB device)
sudo dd if=nixos-minimal-x86_64-linux.iso of=/dev/sdX bs=4M conv=fsync status=progress

2. Prepare the System

Boot from the USB and ensure you have internet:

# Test internet connection
ping google.com

# Clone this repository
git clone https://github.com/jokyv/nixos-config.git /tmp/nixos-config
cd /tmp/nixos-config

3. Set Hostname

Edit hosts/jokyv/default.nix and set your hostname:

networking.hostname = "nixos";  # Change to your preferred hostname

4. (One-time) Add disko to host config

IMPORTANT: For installation ONLY, temporarily add disko to your host config:

In hosts/jokyv/default.nix, add these lines to the imports array:

imports = [
  inputs.disko.nixosModules.disko
  ../../disks/universal-config.nix
  # ... rest of your imports
];

You must remove these after installation! See Post-Installation below.

5. Set User Password

Choose one of these methods:

Option A: Temporary password (simple)

# In hosts/jokyv/default.nix, add:
users.users.jokyv.initialPassword = "changeme";

Remove this line after first boot and set a proper password with passwd.

Option B: sops-nix (secure, recommended)

# Import sops module
import = [ inputs.sops-nix.nixosModules.sops ]

# Define the secret
sops.secrets."pass_jokyv" = { };

# Use it for user password
users.users.jokyv.passwordFile = config.sops.secrets."pass_jokyv".path;

6. Run the Installer

The universal installer will automatically detect the first disk:

# Format and install NixOS
sudo nix run --experimental-features "nix-command flakes" github:nix-community/disko -- --mode disko --flake .#nixos

The installer will automatically format and partition the first available disk.

7. Install NixOS

sudo nixos-install --no-root-password --flake .#nixos

8. Reboot

sudo reboot

Remove the USB stick when the computer turns off.

Option 2: Legacy Manual Configuration

If you need to select a specific disk or use a legacy configuration:

Use lsblk to identify the disk name
Modify the appropriate disk config file in disks/ directory:
- disk-config-btrfs-luks.nix - Btrfs with LUKS encryption
- disk-config-btrfs.nix - Btrfs without encryption
Run the same disko command as above

Post-Installation: CRITICAL STEP

After booting into your new system, you must remove disko from the host configuration to prevent issues with future rebuilds:

# Edit hosts/jokyv/default.nix
nano ~/nixos-config/hosts/jokyv/default.nix

Remove these lines from the imports array:

inputs.disko.nixosModules.disko
../../disks/universal-config.nix

Then verify the configuration works:

sudo nixos-rebuild switch --flake .#nixos

Verify Disko Installation

Check that disko has set up everything correctly:

# Verify tmpfs is mounted
findmnt /tmp

# Verify /var subvolume
findmnt /var

# List all btrfs subvolumes
sudo btrfs subvolume list /

Set up Home Manager

# Clone the repository
git clone git@github.com:jokyv/nixos-config.git ~/nixos-config
cd ~/nixos-config

# Install home-manager temporarily
nix shell -p home-manager

# Apply Home Manager configuration
home-manager switch --flake .#jokyv

# Or use just (if you have justfile installed)
just home

Post-installation Script

After installation, you may want to:

Symlink configurations for tools like aider-chat
Symlink configs to .config - for example, ruff.toml for Python linting
Set up your development environment using devenv/direnv (already included)

Filesystem Options

Btrfs (Recommended)

Advantages: Snapshots, compression, subvolumes
Default subvolumes: /, /home, /nix, /var/log
Built-in compression for better space efficiency
Supports rollback and system snapshots

Ext4

Advantages: Simple, reliable, widely supported
No built-in snapshots or compression
Simpler structure for basic setups

Encryption (LUKS)

Encrypts the root partition (not EFI or swap)
You’ll be prompted for password on every boot
Swap uses random encryption when enabled

Troubleshooting

ERROR: No disks found!

If you see this error during installation:

Check you’re on actual hardware (not in a container/VM)
Verify disks are detected: lsblk
Check permissions: Ensure you can access /dev/disk/by-diskseq/

If the issue persists, manually specify the disk in install-config.nix:

disk = {
  device = "/dev/nvme0n1";  # or /dev/sda
  ...
};

Wrong Disk Selected?

The installer uses /dev/disk/by-diskseq/1 (first disk) by default. To select a different disk, edit install-config.nix:

disk.device = "/dev/nvme0n1";  # Your specific disk

Multiple Disks?

The universal installer handles the first disk. For multi-disk setups, use the legacy configurations in disks/disk-config-*.nix.

Boot Issues?

Check that the disk is detected: lsblk
Verify EFI partition is mounted: mount | grep /boot
Check encrypted partition: lsblk -f
Ensure you removed disko/universal-config from imports after installation

Directory Structure

nixos-config/
├── install-config.nix          # Installation configuration (disk, fs, encryption)
├── disks/
│   └── universal-config.nix    # Auto-detecting disk config (for installation only)
├── hosts/
│   └── jokyv/
│       ├── default.nix         # Host configuration (does NOT import universal-config)
│       └── hardware-configuration.nix  # Generated hardware config with mount points
└── docs/
    └── installation.md         # This file

Important: universal-config.nix is ONLY used during installation. Normal rebuilds use hardware-configuration.nix for filesystem mounts.

Adding New Hosts

To add a new host:

Create hosts/new-host/default.nix
Copy from hosts/jokyv/default.nix
Set networking.hostname to the new hostname
Adjust host-specific settings
For installation: temporarily add inputs.disko.nixosModules.disko and ../../disks/universal-config.nix to imports, then remove after installation
Edit install-config.nix before installing (disk, filesystem, encryption settings)

Then add to flake.nix:

nixosConfigurations = {
  jokyv = nixpkgs.lib.nixosSystem { modules = [ ./hosts/jokyv/default.nix ... ]; };
  new-host = nixpkgs.lib.nixosSystem { modules = [ ./hosts/new-host/default.nix ... ]; };
};

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