Creating a NixOS live CD
motivation
creating a modified NIXOS live CD out of a working nixos installation gives you the benefits:
- verify what is included
- no need to download it
- it is easy to add your own programs to the image
how to build such an image
we will use the NIXREPOS variable, which points to the nixpkgs/nixos checkouts, see Create and debug nix packages
just run this command (for 64 bit):
export NIX_PATH=$NIXREPOS nix-build -A iso_graphical.x86_64-linux $NIXREPOS/nixos/release.nix
for 32 bit:
export NIX_PATH=$NIXREPOS nix-build -A iso_graphical.i686-linux $NIXREPOS/nixos/release.nix
once the building process is over, you should see multiple nix distributions built (for multiple archs). See contents to find iso image path:
$ cat /nix/store/2y4bivmrzg4d2dgby2b7prvfj7445088-nixos-iso-0.1pre1234/nix-support/hydra-build-products file iso /nix/store/94rrfklbk2hcqhkr4627vsrlprlyva50-iso9660-image/iso/nixos-minimal-0.1pre1234-i686-linux-test.iso
and copy the new image from there to your USB drive (or use unetbootin).
adding additional software to the image
the basic script /etc/nixos/nixos/release.nix contains several entry points for custom images. as we are using -A iso_minimal have a look at: iso_minimal which will redirect us to:
- ./modules/installer/cd-dvd/installation-cd-minimal.nix -> /etc/nixos/nixos/modules/installer/cd-dvd/installation-cd-minimal.nix
# This module defines a small NixOS installation CD. It does not
# contain any graphical stuff.
{config, pkgs, ...}:
{
require = [
./installation-cd-base.nix
../../profiles/minimal.nix
];
}
=== Start SSH with your SSH key
In your configuration.nix:
services.openssh = {
enable = true;
hostKeys = [
{ bits = 8192; type = "ed25519"; path = "/etc/ssh/ssh_host_ed25519_key"; }
];
};
# enable ssh in the iso boot process
systemd.services.sshd.wantedBy = lib.mkForce [ "multi-user.target" ];
users.users.root.openssh.authorizedKeys.keys [
"ssh-rsa AAAAB3NzaC1y...== me@my-laptop"
];
software installation inside the 'once' deployed and booted image
in case you have booted from your image you can add software as described here:
references
- See also section "Building your own NixOS CD" of the NixOS manual.