nixos-to-flake.md

From scratch to flake

How to go from the system set up by the installer to the a flake-managed configuration.

Fetch the repo

Enter a shell with git:

nix shell nixpkgs#git --extra-experimental-features nix-command --extra-experimental-features flakes

Then, fetch your configurations

cd .config
git clone https://github.com/user/nixpkgs

Remember to then change remote URL to git@..., after registering the SSH key

Edit the flake

Skip if you want to use an existing configuration.

It is recommended choosing a new hostname, then go to systems/nixos/ and add a new folder named after the chosen hostname.

Then, copy in that folder the file that is located under /etc/nixos/hardware-configuration.nix, and export its content through a default.nix (cf. the existing systems).

Expose the whole system in systems/nixos.nix.

Add any new file and directory to Git, to make it available for the flake (also without committing, but even for that it should be at least staged to make it visible).

Switch to the flake configuration

Finally, switch to the flake by entering:

sudo nixos-rebuild switch --flake .#myhostname

A reboot never hurts ;)

Read also

• This cute world guide on a similar subject