Recently firefox and thunderbird started being rebuilt with cudaSupport enabled because they depend on some other package that now has cuda support. For my laptop with 32GB of ram it takes ages to compile either of them and it eventually runs out of RAM when it's time to link the binary even with --max-jobs 1. It seems that they were added to release-cuda in https://github.com/NixOS/nixpkgs/pull/437809 so they should be cached by the nix-community cache. Yet even after I waited for half a week or more for the new commit to be cached nix still tries to build thunderbird and firefox.
Today I found out about hydra.nixos-cuda.org and decided to try the nixpkgs commit that was built by it https://hydra.nixos-cuda.org/eval/2348 that seems to have thunderbird and firefox cached. Yet nix still tried to build firefox and thunderbird.

This seems to only be possible if hydra.nixos-cuda.org doesn't push to nix-community or if it signs things with a key I don't trust.

Here is my configuration:

          substituters = [
            "https://nix-community.cachix.org"
          ];
          trusted-public-keys = [
            "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
          ];

Does anyone know what I have to do to get build outputs from the cuda hydra?

Two thoughts:

• Helion backend for einops
• Optuna integration with Helion to allow for persistent studies (e.g., if the seed is fixed and the number of generations is increased, the optimization should resume from where it stopped rather than start an entirely new optimization)