Package pdfpc-extractor for NixOS users

[data-niklas]

This PR will add a NixOS flake, which builds the pdfpc-extractor and exposes it as a package.

Usage

1. Add the flake to your own flake.nix as input
2. Use the package inputs.polylux.defaultPackage.${pkgs.system} (under the assumption that the flake was named polylux in your inputs), which will build pdfpc-extractor

Dev env

Either run

• nix build to build the package into the result directory
  or run
• nix develop to enter a dev env where you should be able to run cargo build commands as usual

[andreasKroepelin]

Cool! Can you add a note to the installation section in this file? https://github.com/andreasKroepelin/polylux/blob/main/book/src/external/pdfpc.md

Also, I don't really know much about Nix, so it's hard for me to review... @drupol, can you have a look maybe?

[drupol]

Sure, will do that tomorrow!

I'm using the pdfpc extractor in a presentation, with its own nix file. I'll let you know what I think of this PR tomorrow.

[data-niklas]

I slightly restructured the installation instruction section to streamline instructions for different OS, so we now have 3 subtitles for

• Source
• Arch Linux
• NixOS

[drupol]

Dear @data-niklas,

Here's my take on this:

{
  description = "Polylux packages";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
    systems.url = "github:nix-systems/default";
  };

  outputs = inputs @ { self, flake-parts, ... }: flake-parts.lib.mkFlake { inherit inputs; } {
    imports = [
      inputs.flake-parts.flakeModules.easyOverlay
    ];

    systems = import inputs.systems;

    perSystem = { config, self', inputs', pkgs, system, lib, ... }:
      let
        pdfpc-extractor = pkgs.rustPlatform.buildRustPackage {
          pname = "pdfpc-extractor";
          version = "dev";

          src = ./pdfpc-extractor;

          cargoHash = "sha256-VTJRfDFprKIrwfw5lU9/RnDuGLQ7nXBEc/dms5YVupM=";

          meta.mainProgram = "polylux2pdfpc";
        };
      in
      {
        formatter = pkgs.nixpkgs-fmt;

        overlayAttrs = self'.packages;

        packages = {
          pdfpc-extractor = pdfpc-extractor;
          default = pdfpc-extractor;
        };

        apps = {
          default = {
            type = "app";
            program = lib.getExec self'.packages.pdfpc-extractor;
          };
        };

        devShells.default = pkgs.mkShell {
          name = "polylux-devshell";
          buildInputs = with pkgs; [
            cargo
            rustc
          ];
        };
      };
  };
}

When I have to add a flake to a project, I try to limit to the maximum the external dependencies it depends on to avoid bad surprises. Therefore, I don't think using the contrib project naersk is needed here since we can build pdfpc-extractor with just the nixpkgs repository.
Moreover, I don't think requiring flake-utils is needed as well since we can use flake-parts which is already in nixpkgs and it has a better design (check NixOS Discourse about this).

I also expose pdfpc-extractor in the packages but also as an app that we can just run by doing: nix run github:andreaskroepelin/polylux#pdfpdf-extractor

I don't use the old flake syntax defaultPackages either and there's a default formatter which is set as well.

I forgot to add the default overlay, I will do that as soon as I'm back on a computer.

Let me know what you think of all of this.

PS: I'm currently travelling to Germany to make a talk (where the slides were made with Typst/Polylux) so there might be some delay in my replies.

[data-niklas]

Awesome! I reused the naersk Rust template from another template, as I was not so familiar withe the other methods to package Rust programs. If your version works and is more minimal, great.

How will the cargoHash work between updates? I tried to use your flake locally and got mismatched cargoHashes, as my local version is slightly different. Does it only base the hash on the cargo dependencies?

I think we then need to at least document somewhere, that the cargoHash needs to be updated, when the Rust dependencies change.

Currently it is obtained by inserting a fake checksum into the expression and building the package once

Sadly the checksum would need to be updated by a NixOS user. Alternatively we could try to add the polylux package into nixpkgs, as I assume that pdfpc-extractor is updated less frequently than e.g. the polylux core.

[data-niklas]

Else I would just more or less replace the flake with your more minimal flake

[drupol]

Package has been merged in Nix today @ NixOS/nixpkgs#280525

[data-niklas]

Great! In that case I can and will close this PR.