The Nix Hour

Currently Playing: The Nix Hour #41 [passthru attribute, using services from nixos-unstable]

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 Files from this session: https://github.com/tweag/nix-hour/tree/master/41 00:00 Intro 00:19 Q: How does passthru work and why 01:15 Simple derivation example 02:32 Adding attributes to derivation attrset with // 06:54 Overriding derivation that uses // instead of passthru 09:23 Aside: how runCommand passes script to builder 11:02 Why use passthru instead of // 12:45 How does passthru work 19:10 Escaping env var when passing to derivations 20:40 Q: How to find what attributes that can be set in flakes https://nixos.wiki/wiki/Flakes#Output_schema https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-flake-check.html#evaluation-checks 27:15 Q: Using services from different versions of NixOS in flake 35:02 Aside: How master differs from unstable 38:20 Back to using service available in nixos-unstable 40:34 Aside: Attribute sets and path interpolation to strings 44:20 Back to importing module from nixos-unstable 46:30 Infinite recursion when using NixOS module arguments 47:44 Aside: Using nix-instantiate to build NixOS configuration 52:03 Back to infinite recursion, specialArgs 53:41 Adding package from unstable to NixOS configuration with nixpkgs.overlays 59:16 Outro