The Nix Hour

Currently Playing: The Nix Hour #5 [overriding a rust source, derivation internally, closure inspection]

The Nix Hour is a weekly beginner-oriented improvised 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. The Nix hour happens every week, is open to the public and is recorded and uploaded to the Tweag YouTube channel. For more info check out https://discourse.nixos.org/t/the-nix-hour-a-weekly-nix-qa-lecture-by-tweag/22767 This week we looked at these topics: 00:00 Overriding the source of a Rust package in an overlay 05:50 Impure overlay locations 06:49 Not providing a hash to different fetchers 11:53 Providing the overlay on the CLI instead of impurely 13:44 Discussion about derivation names 15:02 Looking how buildRustPackage is implemented and figuring out how to override the dependency hash 19:30 Actually overriding the dependency hash 21:18 Discussion on whether the name matters for fixed-output derivation caching 23:02 Looking at the Nix store database directly with sqlite 23:59 Checking discourse for how to override rust packages dependency hashes 25:05 Why outputHash? 28:34 Asking for questionsA 30:15 Inspecting derivation attributes 33:16 The derivation primitive 36:37 The derivationStrict primitive underneath the derivation primitive 38:18 Nix repl requirements for a derivation 39:52 Why derivation attributes aren't needed to build derivations 44:10 Derivation inputs 45:20 Inspecting build-time dependencies of derivations 47:07 Finding the derivation for a store path using nix-store --query --deriver 49:20 Subpar explanation of some GC related nix.conf options 52:12 Manually replicating Nix's grepping for runtime dependencies 55:38 Looking at references schema in the Nix database 56:02 Looking at the GC related options again and some recommendations