helm/doc/start/from-nixos.md

From NixOS

Generate Configuration

Assuming you're happy with your existing partition layout, you can generate a basic NixOS configuration for your system using:

flk up

This will make a new file hosts/up-$(hostname).nix, which you can edit to your liking.

You must then add a host to nixos.hosts in flake.nix:

{
  nixos.hosts = {
    modules = hosts/NixOS.nix;
  };
}

Make sure your i18n.defaultLocale and time.timeZone are set properly for your region. Keep in mind that networking.hostName will be automatically set to the name of your host;

Now might be a good time to read the docs on suites and profiles and add or create any that you need.

Note:

While the up sub-command is provided as a convenience to quickly set up and install a "fresh" NixOS system on current hardware, committing these files is discouraged.

They are placed in the git staging area automatically because they would be invisible to the flake otherwise, but it is best to move what you need from them directly into a host module of your own making, and commit that instead.

Installation

Once you're ready to deploy hosts/my-host.nix:

flk my-host switch

This calls nixos-rebuild with sudo to build and install your configuration.

Notes:

• Instead of switch, you can pass build, test, boot, etc just as with nixos-rebuild.

• It is convenient to have the template living at /etc/nixos so you can simply sudo nixos-rebuild switch from anywhere on the system, but it is not required.