Overview

Core Concepts

Context Transformation

Declarative pipeline that flows configuration through named context types — host, user, home, and custom. Learn More

Context-Aware Aspects

Aspects are functions of context. A single aspect can target NixOS, Home-Manager, Darwin, and more — resolved automatically by context. Learn More

Context Pipeline

Stage-by-stage flow from host entry through user enumeration, HM detection, deduplication, and standalone homes. Learn More

Context System

Named context types with den.ctx schema — providers, includes, transformations, fan-out, and 10+ built-in context types. Learn More

Parametric Aspects

den.lib.parametric with matching variants: atLeast, exactly, fixedTo, expands, withOwn, and take functions. Learn More

Library vs Framework

Den’s dual nature — use the pure library for custom pipelines, or the framework for NixOS/Darwin/HM. All parts optional and replaceable. Learn More

Configuration & Schema

Declare Hosts & Users

Define hosts with class detection, custom attributes, multiple users, standalone HM, base modules, and custom instantiation. Learn More

Configure Aspects

Static host config, context-aware includes, bidirectional user/host config, conditional config, global defaults, and named sub-aspects. Learn More

Schema Reference

Entity schemas for den.hosts, den.homes, den.base — host options, user options, home options, class detection, and instantiation. Learn More

Output & Build

How Den builds nixosConfigurations, darwinConfigurations, and homeConfigurations. Output placement, main module resolution. Learn More

Aspects Reference

Aspect attribute table, automatic creation from den.hosts/den.homes, resolution via flake-aspects, den.aspects and den.provides. Learn More

Context Reference

All built-in context types in detail: host, user, default, home, hm-host, hm-user, maid-host, maid-user, hjem-host, hjem-user. Learn More

Home & User Management

Home Manager Integration

Automatic HM detection, host-managed users, standalone HM, useGlobalPkgs, custom modules, osConfig access, and context hooks. Learn More

Custom Classes

Create new Nix classes with den._.forward — hjem, maid, containers, VMs, guarded forward with conditions. Learn More

User Classes

Default homeManager class, multiple user classes, per-class aspect resolution, OS user class forwarding. Learn More

Bidirectional Config

Host-owned config applies to all users; user-owned config applies to all hosts. Static, parametric, and function-based. Learn More

Standalone Homes

Standalone homeConfigurations output — aspect config, custom username, den.ctx.home context, independent of any host. Learn More

Hjem & Maid Classes

Built-in hjem and maid user class support — forwarding, merge with NixOS, automatic class detection. Learn More

OS User Class

Forward user descriptions, access OS args like pkgs, mergeable options across user/host/NixOS boundaries. Learn More

Batteries Included

define-user

den._.define-user — creates isNormalUser, sets home directory, works at user, host, or default level. Learn More

primary-user

den._.primary-user — adds wheel and networkmanager groups to the primary user. Learn More

user-shell

den._.user-shell — sets the user shell on both OS and Home-Manager simultaneously. Learn More

unfree

den._.unfree — sets allowUnfreePredicate on both NixOS and Home-Manager. Learn More

tty-autologin

den._.tty-autologin — creates a getty autologin service for the user. Learn More

import-tree

den._.import-tree._.host — auto-imports host directories based on class, handles missing dirs gracefully. Learn More

inputs' & self'

den._.inputs' and den._.self' — provide flake-parts special args (inputs', self') inside aspects. Learn More

forward

den._.forward — forward aspect config into custom Nix classes with optional guard conditions. Learn More

Batteries Guide

Overview and usage guide for all built-in batteries — when to use each one, practical examples, and composition patterns. Learn More

Library API

den.lib Reference

Full API: parametric, take, canTake, aspects, isFn, owned, statics, isStatic, __findFile. Learn More

Angle Brackets

Opt-in <den/...> shorthand — access <den.lib>, <den/import-tree/host>, namespaces like <ns/path>. Learn More

Namespaces

Define local namespaces, consume remote ones, nested provides, expose as flake output, merge multiple sources. Learn More

Cross-Provider Contexts

den.ctx.*.into.* cross-provider derivation — transform config between context types, per-value providers. Learn More

Host Propagation

Full propagation: owned, static, lax, exact, atLeast contexts with default includes, hm-host, and hm-user stages. Learn More

Default Includes

den.default.includes — global defaults applied to all hosts/users, dynamic class resolution, hostname from context. Learn More

Schema Base Modules

den.base.conf, den.base.host, den.base.user, den.base.home — extend entity schemas with custom modules. Learn More

Custom Instantiation

Override instantiate for standalone HM with osConfig special arg, or custom deployment targets. Learn More

Conditional Config

Conditional NixOS imports based on host/user attributes. Per-user HM config. Static aspects in defaults. Learn More

External Providers

Consume aspects from external flakes. Provider flake integration, deep nested namespace aspects. Learn More

Getting Started

Minimal Template

Smallest possible setup — one host, one user, no extra deps. Single flake.nix + modules/den.nix. Learn More

Default Template

Recommended starting point with flake-parts, Home-Manager, and VM testing. Full file walkthrough. Learn More

Example Template

Advanced: cross-platform hosts, namespaces, angle brackets, bidirectional providers, custom routes. Learn More

No-Flake Template

Using Den with stable Nix via npins. No flakes required. Works with nix-maid. Learn More

Bogus / Bug Report

Bug reproduction template with nix-unit. denTest helper and available test fixtures. Learn More

Templates Overview

Comparison table of all 6 templates, quick start commands, project structure. Learn More

Advanced & Operations

Migration Guide

Incremental adoption from flake-parts, import existing modules, mix Den with existing nixosSystem, recommended path. Learn More

Debugging

builtins.trace, builtins.break, REPL inspection, manually resolving aspects, common issues. Learn More

CI Test Suite

40+ test files covering every feature. Run tests, write new ones, understand test harness (denTest, evalDen). Learn More

Community & Project

Motivation & History

Why Den exists — from vic/vix through blueprint, snowfall, and flake-parts to dendritic design. Learn More

Community

GitHub Discussions, Zulip Chat, Matrix channel, real-world examples, ecosystem projects. Learn More

Contributing

Report bugs, contribute PRs, run tests, format code. Learn More

Sponsor

Support Den development via GitHub Sponsors. Learn More