configuring-layers

NixOS configuration layering resolves option conflicts by applying a seven-level hierarchy—Common, Platform, Home, Suite, Archetype, Host, and User—with defined precedence rules so defaults, host overrides, and user customizations never clash across multi-machine environments.

The best way to decide is following a step-by-step decision tree that evaluates the change scope from common modules down to host configs and user customizations, placing options in the most specific layer necessary to avoid unintended overrides.

Configuration layering precedence works by applying defaults at the Common level, escalating through Platform and Host layers, and resolving with strong User overrides, ensuring higher-level customizations cleanly supersede lower-level defaults without conflicts.

Yes, layered configuration strategies apply to both host and home-manager user customizations by mapping changes across the seven levels, allowing platform-wide defaults to coexist with specific host configs and individual user home settings.

You should avoid a multi-level configuration hierarchy for simple, single-machine NixOS setups where the overhead of managing seven layers outweighs the benefit of structured conflict resolution, as a flat configuration suffices without drift risks.