from Hacker News

Improved evaluation times with pre-resolved Nix store paths

by biggestlou on 2/12/25, 3:05 PM with 48 comments

• by asmor on 2/12/25, 3:35 PM

  DetSys, once again, building a moat.

  I really do not like how this approach depends on their seemingly not open source backend. Nix needs tools like this, no question, but I'd hate to see it get adoption through a way that isn't reproducible by anyone. It looks like it could be a repeat of the Snap store problem - interesting tech, made unusable through de-facto dependencies on proprietary services.

• by jljljl on 2/12/25, 5:00 PM

  This is cool! We do something similar in Devbox where we pre-evaluate store paths from the Nix repository, and then fetch the packages directly from the official Nix cache. This greatly reduces the evaluation time.

  Here's a blog post we wrote on the topic:

  https://www.jetify.com/blog/how-we-sped-up-nix-package-insta...

• by biggestlou on 2/12/25, 3:35 PM

  Blog post author here! Please feel free to ask me any questions directly in this forum :)

• by pinetroey on 2/15/25, 7:49 PM

  Is this similar to, using nixos-rebuild and target a second machine?

  I use my laptop's nixos-rebuild and push a new generation to another device. The 2nd device doesn't have the config, so it won't be able to build it. For these devices, I don't want the config to be on the 2nd device.

• by mongol on 2/12/25, 3:38 PM

  This will make discourse.nixos.org explode again. It happens every time Determinate System publishes something.

• by knoopx on 2/12/25, 4:08 PM

  what a coincidence, my eval times have worsened over the past months too!