Documentation Structure

Understand

Core Concepts

How Nest’s mental model works and why it’s designed this way.

CSS for Nix How the CSS analogy maps to NixOS configuration — DOM, traits as classes, rules as stylesheets.

The DOM How Nest traverses your attrset hierarchy, builds node contexts, and propagates inherited attributes.

Traits Entity types, marker traits, dependency DAGs with needs/neededBy, and bottom-up synthesis.

The Pipeline The seven-step evaluation pipeline from DOM walk to nixosConfigurations output.

Guides

How-To Guides

Step-by-step walkthroughs and practical examples.

Getting Started A minimal working example: one host, one trait, one rule. Everything you need to understand the basics.

Multi-Environment Fleet Prod and staging environments with a load balancer, web servers, haproxy backend discovery, and /etc/hosts synthesis.

Dynamic User Assignment Define users once in a registry, synthesize them as DOM children on each host based on environment policy.

Reference

API Documentation

Complete reference for every selector, trait API, and the select context.

Selectors All selector forms: trait, star, id, name, attr, attrs, or, not, has, within, when, class, child, descendant.

Traits class, needs, neededBy, synth — full trait API with examples.

Rules Rule format, class keys, function-valued rules, and the synth key.

Select API The select context: node, parentNode, siblings, children, parents, parent, within — and the default filter functor.

CSS Syntax String-based CSS selector syntax: #id, .class, [attr], combinators, pseudo-classes.

flakeModule Integrating Nest with flake-parts: options, byClass routing, output classes.