nixos-config/docs/website/content/en/03-project-specific-setup/01-declarative-host-management/index.adoc

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title: Declarative host management --- = Declarative host management

This project uses a custom setup for declarative host management. It is a custom github:hercules-ci/flake-parts[opts=repo] module that allows you to easily initialize NixOS systems of multiple platforms (with multiple images output) while making it purely-built as much as possible.

This custom flake-parts modules integrates the following projects:

• It automatically adds github:serokell/deploy-rs[opts=repo] nodes ready to be deployed with deploy CLI tool when given the right parameters.

• Mandatory inclusion of github:nix-community/home-manager[opts=repo].

• Image output generation made easy with github:nix-community/nixos-generators[opts=repo].

Each of the declared hosts are then exported either as part of the images or nixosConfigurations (or both) flake output attribute. The images flake output attribute contains a per-system set of packages of the NixOS systems as the indicated package format. For example, you can build my personalized NixOS installer ISO with the following command.

nix build {canonical-flake-url}#images.x86_64-linux.bootstrap-install-iso

The following code listing is an example of a declarative NixOS setup. It should have the following effects in the flake output:

• Two additional NixOS configurations to be deployed at nixosConfigurations.plover-{x86_64-linux,aarch64-linux}. By default, declarative NixOS setups are not added automatically to nixosConfigurations output unless we have configs.<config>.formats = null; but we did configure configs.<config>.deploy so that makes it even.

• Four additional derivations added in images flake output (since there’s 2 formats and 2 platforms) at images.{x86_64-linux,aarch64-linux}.plover-{do,gce}.

{
  setups.nixos.configs.plover = {
    systems = [ "x86_64-linux" "aarch64-linux" ];
    formats = [ "do" "gce" ];
    domain = "foodogsquared.one";
    nixpkgsBranch = "nixos-unstable-small";
    homeManagerBranch = "home-manager-unstable";
    modules = [
      ({ config, lib, ... }: {
        services.foo.enable = true;
      })
    ];
    overlays = [
      inputs.neovim-nightly-overlay.overlays.default
    ];
    deploy = {
      fastConnection = true;
      autoRollback = true;
      magicRollback = true;
      remoteBuild = true;
      profiles = os: {
        system = {
          sshUser = "root";
          user = "admin";
          path = inputs.deploy.lib.${os.system}.activate.nixos os.config;
        };
      };
    };
  };
}