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

Tip

Usually, you’d make this your default package, so as to be able to use nix run. In flake.nix:

# 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@

Note

The activate app will activate the home-manager configuration if the argument contains a @ (separating user and the optional hostname). The above command has no hostname, indicating that we are activating for the local host.

Note

The activate app will move your existing dotfiles out of the way with a timestamped backup extension. For example, your existing ~/.zshrc will be backed up in ~/.zshrc.nixos-unified.2025-01-15-22:29:54.bak.

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:

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

Note

Remote home-manager activation uses the user@host format for the SSH connection, where the user is extracted from the configuration name and the host is 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.

Note

It is possible however that nixos-unified can grow to support more sophisticated deployment capabilities