Creating a NixOS live CD

Motivation

Creating a modified NixOS LiveCD out of an existing working NixOS installation has a number of benefits:

• Ensures authenticity.
• No need for internet access.
• It is easy to add your own packages and configuration changes to the image.

Building

Create a file iso.nix:

# This module defines a small NixOS installation CD.  It does not
# contain any graphical stuff.
{config, pkgs, ...}:
{
  imports = [
    <nixpkgs/nixos/modules/installer/cd-dvd/installation-cd-minimal.nix>

    # Provide an initial copy of the NixOS channel so that the user
    # doesn't need to run "nix-channel --update" first.
    <nixpkgs/nixos/modules/installer/cd-dvd/channel.nix>
  ];
}

Build the image via:

nix-build '<nixpkgs/nixos>' -A config.system.build.isoImage -I nixos-config=iso.nix

The resulting image can be found in result:

$ ls result/iso/
nixos-17.09.git.158ec57-x86_64-linux.iso

SSH

In your iso.nix:

{
  ...
  # Enable SSH in the boot process.
  systemd.services.sshd.wantedBy = lib.mkForce [ "multi-user.target" ];
  users.users.root.openssh.authorizedKeys.keys [
    "ssh-ed25519 AaAeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee username@host"
  ];
  ...
}

Static IP Address

Static IP addresses can be set in the image itself. This can be useful for VPS installation.

{
  ...
  networking = {
    usePredictableInterfaceNames = false;
    interfaces.eth0.ip4 = [{
      address = "64.137.201.46";
      prefixLength = 24;
    }];
    defaultGateway = "64.137.201.1";
    nameServers = [ "8.8.8.8" ];
  };
  ...
}

ZFS Support

NixOS ISOs do not contain ZFS tools and kernel modules by default. They can be added via:

{
  ...
  boot.supportedFilesystems = [ "zfs" ];
  ...
}

See also

• NixOS Manual: Building your own CD.