Nix flake build suddenly takes forever in GitHub action

Hello friends,

I have a project which builds a rust and a node program into a docker container with a nix flake build. Here is my flake.nix. When I build it locally it takes a reasonable time to build, well under one minute.

Now to the actual problem I need help with: I have a GitHub action build pipeline which builds and publishes the container image. As of recent builds it takes a few hours to build the container image via nix build. As you can see in the history of the runs, I haven’t changed anything related to the build when it started taking so long. Since I use a flake lock and a tagged version of the install nix action I am out of ideas where I should look for further clues.

Thanks in advance for ideas and help :smile:

For some reason the long build also build NodeJS
(/nix/store/i6hr3qai2hc41i8i6a8i3d0rj1gmkxzj-nodejs-18.16.0.drv) while e.g. feat(button): prettify compile button · jgero/j-k-ratio-plus-L@fbfda77 · GitHub doesn’t.

Whatever the reason, it seems the :magic_wand: Magic Cache was just announced in time to ease your woes :slight_smile:

2 Likes

oh wow that looks mega, I’ll check it out further, thanks!

I’m using the magic cache now and magically it works now, thank you very much for you help, much appreciated :smiley: