Registry Visualization

When your configuration grows complex enough, understanding which modules import what becomes genuinely difficult. The visualization tool generates an interactive dependency graph.

Setup

Visualization requires the imp-graph input. Add it to your flake and import the visualization module:

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    flake-parts.url = "github:hercules-ci/flake-parts";
    imp.url = "github:imp-nix/imp.lib";
    imp-graph.url = "github:imp-nix/imp.graph";
    imp-graph.inputs.nixpkgs.follows = "nixpkgs";
  };

  outputs = inputs@{ flake-parts, imp, ... }:
    flake-parts.lib.mkFlake { inherit inputs; } {
      imports = [
        imp.flakeModules.default
        imp.flakeModules.visualize
      ];
      imp = {
        src = ./outputs;
        registry.src = ./registry;
      };
    };
}

The module activates automatically when it detects the imp-graph input. This adds two apps: visualize (a standalone tool) and imp-vis (which uses your configured registry).

Usage

nix run .#imp-vis > deps.html
nix run .#imp-vis -- --format=json > deps.json

Open the HTML file in a browser. Nodes represent registry entries, connected by edges for each registry.X.Y reference found in source files. Hover over a node to highlight its connections. Drag to reposition. Scroll to zoom.

The standalone visualize app works without registry configuration:

nix run .#visualize -- ./path/to/nix > deps.html

Reading the graph

Nodes are colored by cluster (hosts, modules.home, modules.nixos). Sink nodes (final outputs like nixosConfigurations) appear larger with labels. Nodes with identical edge topology are merged to reduce visual clutter.

Edges show registry.X.Y references found in each file. A dashed edge from hosts.server to modules.nixos.base means the server host imports that base module.

JSON format

For programmatic access:

{
  "nodes": [{ "id": "hosts.server", "cluster": "hosts" }],
  "edges": [{ "from": "hosts.server", "to": "modules.nixos.base" }]
}