Including an external package in texlive.withPackages

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1

Hi everyone,

I’m running into an issue when building a custom LaTeX environment using Nix flakes. My setup combines the full TeX Live distribution (texliveFull) with an external LaTeX class (lipics). The build fails with a “Permission denied” error related to creating a symlink in the Nix store.

Error Message

Here’s the error message I receive during the build process (hashes removed):

texlive: generating format symlinks
ln: failed to create symbolic link '/nix/store/...-texlive-2023-env/share/texmf/...-texlive-2023-env-texmfdist': Permission denied
error: builder for '/nix/store/...-texlive-env.drv' failed with exit code 1;

Here is the full log.

Flake Configuration

Below is a minimal reproduction flake.nix. This, and other required files, are available on GitHub.

{
  description = "A Nix flake to build a LaTeX document using TeX Live and TikZ";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs";
  };

  outputs = { self, nixpkgs }:
    let
      system = "x86_64-linux";
      pkgs = import nixpkgs { inherit system; };
      lipicsPkg = pkgs.stdenv.mkDerivation {
        name = "lipics";
        pname = "lipics";
        src = ./lipics;
        outputs = [ "out" "tex" ];
        installPhase = ''
          mkdir -p $out/share/texmf/tex/latex/lipics/
          mkdir -p $tex/tex/latex/lipics/
          cp *.cls $out/share/texmf/tex/latex/lipics/
          cp *.cls $tex/tex/latex/lipics/
        '';
      };
      texliveBundle = pkgs.texliveFull.withPackages (ps: [
        ps.latexmk
        lipicsPkg
      ]);
    in
    {
      packages.${system}.default = pkgs.stdenv.mkDerivation {
        name = "build-paper";
        src = ./.;
        nativeBuildInputs = [
          texliveBundle
        ];
        buildPhase = ''
          export XDG_CACHE_HOME=$(mktemp -d)
          latexmk -pdf --shell-escape paper.tex
        '';
        installPhase = ''
          mkdir -p $out
          cp paper.pdf $out/
        '';
      };
    };
}

This flake does the following:

  1. Defines a custom derivation (lipicsPkg) for the external LaTeX class lipics, which includes lipics-v2021.cls.
  2. Combines this package with texliveFull using withPackages.
  3. Builds a minimal LaTeX document (paper.tex) that uses the lipics class.

The only files other than the flake that are needed are:

  • lipics/lipics-v2021.cls: The custom LaTeX class.
  • paper.tex: A minimal LaTeX document that incrrentcludes the lipics class.

Observations

  • The error occurs during the symlink creation phase of the TeX Live environment setup.
  • If I remove the external package (lipicsPkg), the build succeeds without issues.
  • If I change the TeX Live bundle constructor to texlive.combine then
  • Based on my understanding, TeX Live tries to generate symlinks dynamically during its configuration phase, which seems to conflict with Nix’s immutability constraints.
  • This appears to be related to GitHub issue 10375, however this is marked as fixed, so I shouldn’t be seeing this in my current version.

Questions

  1. What is causing this symlink permission error when adding an external package to the TeX Live environment?
  2. Is it intended to create this symlink or is the symlink being created by an error in my flake.
  3. Is there a way to configure TeX Live or Nix to avoid writing symlinks directly into the Nix store?
  4. Are there alternative approaches for including external LaTeX packages in a TeX Live environment built with flakes?

Any help or insights would be greatly appreciated!

2

I got worried for a moment! The bug is actually in this line:

TeX Live owns the directory $out/share/texmf so you can never add content to it. You should remove the out output from lipicsPkg, or at least leave it empty.

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