Activation

nixos-unified provides an .#activate flake app that can be used in place of nixos-rebuild switch (if using NixOS),darwin-rebuild switch (if using nix-darwin) or home-manager switch (if using home-manager)

In addition, it can remotely activate the system over SSH (see further below).

Activating NixOS or nix-darwin configurations

In order to activate a system configuration for the current host ($HOSTNAME), run:

nix run .#activate

Passwordless local NixOS activation

By default, local NixOS activation runs nixos-rebuild switch --sudo, so nixos-rebuild decides when to invoke sudo for privileged steps.

If you want sudoers to match a single command, configure the target host to run nixos-rebuild itself through sudo:

{
  nixos-unified.localPrivilegeMode = "sudo-nixos-rebuild";
}

This makes the activator run /run/current-system/sw/bin/nixos-rebuild via sudo. Add a narrowly scoped sudoers rule for the user and command you use for activation:

{
  security.sudo.extraRules = [
    {
      users = [ "myuser" ];
      commands = [
        {
          command = "/run/current-system/sw/bin/nixos-rebuild switch *";
          options = [ "NOPASSWD" ];
        }
      ];
    }
  ];
}

# In perSystem
{
    packages.default = self'.packages.activate
}

Activating home configuration

If you are on a non-NixOS Linux (or on macOS but you do not use nix-darwin), you will have a home-manager configuration. Suppose, you have it stored in legacyPackages.homeConfigurations."myuser" (where myuser matches $USER), you can activate that by running:

nix run .#activate $USER@

Per-host home configurations

You may also have separate home configurations for each machine, such as legacyPackages.homeConfigurations."myuser@myhost". These can be activated using:

nix run .#activate $USER@$HOSTNAME

This will activate the home-manager configuration for the specified host over SSH (see below).

Remote Activation

nixos-unified acts as a lightweight alternative to the various deployment tools such as deploy-rs and colmena. The .#activate app takes the hostname as an argument and supports remote activation for both system configurations (NixOS/nix-darwin) and home-manager configurations.

Remote System Activation

For NixOS or nix-darwin configurations, set the nixos-unified.sshTarget option in your configuration:

{
    nixos-unified.sshTarget = "myuser@myhost";
}

Then, you will be able to run the following to deploy to myhost from any machine:

nix run .#activate myhost

Remote Home-Manager Activation

For home-manager configurations, remote activation works by specifying the user and hostname:

nix run .#activate myuser@myhost

This will:

1. Copy the flake and necessary inputs to the remote host via SSH
2. Run the home-manager activation remotely on the target machine

Non-goals

Remote activation doesn’t seek to replace other deployment tools, and as such doesn’t provide features like rollbacks. It is meant for simple deployment use cases.