The Nix Hour

Currently Playing: The Nix Hour #40 [debugging and tracing NixOS modules]

Questions can only be asked by voice or chat in the meeting: https://meet.jit.si/nix-hour The Nix Hour is an open beginner-oriented Q&A-style lecture on Nix, where you can bring your questions and we’ll answer them with more context, examples, alternatives, tradeoffs and related topics. Matrix room for questions, feedback and notifications: https://matrix.to/#/%23nix-hour:matrix.org Issue tracker for asynchronous questions: https://github.com/tweag/nix-hour/issues Previous sessions playlist: https://www.youtube.com/playlist?list=PLyzwHTVJlRc8yjlx4VR4LU5A5O44og9in For more information and updates, check out https://discourse.nixos.org/t/the-nix-hour-a-weekly-nix-qa-lecture-by-tweag/22767 00:00 Intro 01:11 Q: Debugging derivations with Nix trace 02:32 Simplest NixOS module scaffolding 03:45 Aside: Catch-all NixOS types (raw, anything) 06:27 Getting a confusing error from NixOS module system 10:54 Difference from Nix 2.3 12:41 Adding information to the trace with builtins.addErrorContext 14:45 Looking at PR#8623: Stack trace improvements https://github.com/NixOS/nix/pull/8623 18:42 Back to NixOS modules example 19:33 lib.types.string is deprecated in favor of str 25:05 Providing overridable defaults for NixOS options 32:17 Pattern for overridable settings 34:02 Injecting pkgs argument into module system without NixOS 35:15 Strict evaluation and derivations 36:14 nix-instantiate traverses attribute sets 37:15 Creating options for values derived from other options 41:00 Q: How to use pasthru.tests outside nixpkgs? 50:50 Q: Changing dbeaver version in nixpkgs 52:39 Issue with passing arrays to builder as arguments, pkgs.lib.escapeShellArgs 57:37 Outro