nixos-configuration

The collection of publically visible nixos-configuration files used for all of my NixOS machines. Deployment (both local and remote) is managed using colmena. All machines can be found in the top-level flake.nix file.

Local Machines

My personal laptop configuration is reflected in the top-level framework directory (named after the framework laptop I use). This flake defines a home-manager configuration for a single user called jrpotter. We can apply a nixos-rebuild switch by running:

$ nix flake update  # If any changes were made to local machines.
$ colmena apply-local [--sudo]

Remote Machines

Remote machines are hosted on DigitalOcean. The custom image used by each droplet can be built using the top-level images/digital-ocean-23.11pre-git flake. This image disables a root password in favor of SSH. A droplet running this image will automatically pull in any enabled SSH keys from your DigitalOcean account at creation time (so make sure to include them when creating a new droplet).

Secrets

Secrets are managed via sops-nix. The top-level .sops.yaml configures the age keys used to encrypt all secrets. Once configured, you can create/edit a new secrets file using sops like so:

$ nix-shell -p sops --run "sops <filename>"

Keep in mind that sops-nix supports YAML, JSON, INI, dotenv and binary at the moment. What format is used is determined by <filename>'s extension.

Admins

To generate a new user-controlled key, you will need an ed25519 SSH key. Generate one (if you do not already have one) by running:

$ ssh-keygen -t ed25519 -C "<email>"

You can then generate an age secret:

$ mkdir -p ~/.config/sops/age
$ nix-shell -p ssh-to-age --run \
    "ssh-to-age -private-key -i <ssh-file> > ~/.config/sops/age/keys.txt"

and find its corresponding public key:

$ nix-shell -p ssh-to-age --run "ssh-to-age < ~/.ssh/id_ed25519.pub"

This public key can then be written into the .sops.yaml file.

Servers

Each machine that needs to decrypt secret files will also need to be registered. To do so, run:

$ nix-shell -p ssh-to-age --run 'ssh-keyscan <host> | ssh-to-age'

This will look for any SSH host ed25519 public keys and automatically run through ssh-to-age. Include an appropriately top-level keys entry in .sops.yaml before generating the secrets needed by the machine. Refer to phobos for an example.

Deployment

Like our local configurations, remote updates are managed by colmena. colmena requires non-interactively connecting over the ssh-ng protocol meaning you must add the appropriate private SSH key to an ssh-agent before deploying:

$ eval $(ssh-agent -s)
$ ssh-add ~/.ssh/id_ed25519

Afterward you can run the following:

$ nix flake update  # If any changes were made to remote machines.
$ colmena apply