Lightmeter [Nixified]

Funded by the European Commission under the Next Generation Internet initiative

Objective

1. Package Lightmeter for NixOS
2. Allow usage of Lightmeter through the module system for NixOS

Current State

As of 2020, September 16, this flake is in a working state and achieving all of its objectives.

Usage

Instructions were last updated on 2020, September 16.

Building the Package (Nix)

If you are using Nix 2.x, compatibility is provided through github:edolstra/flake-compat, as such the package can be built with just nix-build in the current directory or more verbosely, nix-build -A packages.x86_64-linux.lightmeter. If you do not want to clone the repository, then you can add the repository into NIX_PATH by including -I lightmeter=https://github.com/ngi-nix/lightmeter/tarball/master '<lightmeter>' which can also be pinned at a certain commit, such as a32bfe25a5c8bafa0297a75327693b13240723ea.

If you are using Nix 3.x, cloning the repository isn't needed and one can just run nix build github:ngi-nix/lightmeter or more verbosely, nix build --print-build-logs github:ngi-nix/lightmeter#packages.x86_64-linux.lightmeter.

Using the Module (NixOS)

To enable the lightmeter module in NixOS, you will have to use lightmeter.nix and package in lightmeter.nix

This will only cover the flake-based approach (Nix 3.x), but can be expanded for Nix 2.x compatibility.

To include github:ngi-nix/lightmeter into your flake, you will first have to include it as an input like the following

{
  #...
  # Can be consistently pinned at a certain revision with `rev = ""`
  inputs.lightmeter = { type = "github"; owner = "ngi-nix"; repo = "lightmeter"; };
  #...
  # Or just `{ self, nixpkgs, lightmeter }` but that doesn't cover all cases
  outputs = { self, nixpkgs, ... }@inputs:
  #...
}

Before including the module and overlay into the system configuration

{
  #...
  nixosConfigurations.<name> = nixpkgs.lib.nixosSystem {
    system = "<system>";
    modules = [
      #...
      ({ ... }: {
        # Or just `imports = [ inputs.lightmeter.nixosModules.lightmeter ]`
        imports = builtins.attrValues inputs.lightmeter.nixosModules;
        nixpkgs.overlays = [ inputs.lightmeter.overlay ];
      })
      #...
    ];
  };
  #...
}

In which you can enable the service afterwards

{
  #...
  nixosConfigurations.<name> = nixpkgs.lib.nixosSystem {
    system = "<system>";
    modules = [
      #...
      ({ ... }: {
        services.lightmeter.enable = true;
        # Or to watch a file use the following command
        #   services.lightmeter.flags.watch_file = "/etc/postfix/mail.log";
        services.lightmeter.flags.watch_dir = "/etc/postfix";
      })
      #...
    ];
  };
  #...
}

Using the Virtual Machine Testbed

See REVIEW.md