Duskmoon Bundler

Duskmoon Bundler

Use DuskmoonBundler as the Phoenix asset toolchain for JavaScript, TypeScript, CSS, Tailwind v4, HMR, production manifests, JS/TS formatting and linting, and npm package management through duskmoon_npm. Keep setup small and prefer the installer unless the user is in an umbrella, custom endpoint, or migration path that needs manual edits.

Current repository package version: 9.7.1 for duskmoon_bundler, duskmoon_bundler_runtime, and duskmoon_npm.

Setup Path

Prefer the Igniter installer for normal Phoenix apps:

mix igniter.install duskmoon_bundler
mix phx.server

The installer should remove esbuild and tailwind, add the DuskmoonBundler deps, add config, add DuskmoonBundler.DevServer, add the dev watcher, update asset aliases, and register DuskmoonBundler.Formatter.

Treat DuskmoonBundler plus duskmoon_npm as the replacement for Phoenix's esbuild/Tailwind binary setup and Bun/npm/yarn package install workflows. Use Mix tasks such as mix npm.install instead of bun add, bun install, npm install, or yarn install.

Use manual setup when reviewing, repairing, or configuring an app without running Igniter. Add both dependencies:

def deps do
  [
    {:duskmoon_bundler_runtime, "~> 9.7"},
    {:duskmoon_bundler, "~> 9.7", runtime: Mix.env() == :dev}
  ]
end

Do not set :duskmoon_bundler to only: :dev; production asset aliases often run under MIX_ENV=prod. The runtime: option keeps the build toolchain out of releases while leaving Mix tasks available.

duskmoon_npm is a DuskmoonBundler dependency. Add it explicitly only when a project needs npm package-management tasks without depending on :duskmoon_bundler:

{:duskmoon_npm, "~> 9.7"}

NPM Package Management

Use duskmoon_npm for package manifests, installs, scripts, and local package binaries. It reads package.json, resolves npm semver, writes npm.lock, links node_modules/, and keeps package installation inside Mix.

For a new project:

mix npm.init
mix npm.install

For existing dependencies after cloning or editing package.json:

mix npm.install

Add packages through Mix instead of Bun/npm/yarn:

mix npm.install lodash
mix npm.install @types/node@^20
mix npm.install eslint --save-dev
mix npm.install lodash --save-exact

Use CI/frozen installs when the lockfile must not drift:

mix npm.ci
mix npm.install --frozen
mix npm.verify

Run package scripts and local binaries with:

mix npm.run build
mix npm.exec eslint .

For umbrella Phoenix assets, prefer one root package.json with workspaces and per-web-app manifests for apps that own assets:

{
  "name": "my_umbrella",
  "private": true,
  "workspaces": ["apps/*"]
}

Run mix npm.install from the umbrella root so duskmoon_npm resolves the root manifest and all workspace manifests into one root npm.lock and node_modules/.

Commit package.json and npm.lock. Do not commit node_modules/. Package lifecycle hooks are not executed automatically; packages declaring install hooks are installed with warnings for supply-chain safety.

Build Config

Configure a single app in config/config.exs:

config :duskmoon_bundler,
  entry: "assets/js/app.ts",
  root: "assets",
  target: :es2020,
  sourcemap: :hidden,
  tailwind: [
    css: "assets/css/app.css",
    sources: [
      %{base: "lib/", pattern: "**/*.{ex,heex}"},
      %{base: "assets/", pattern: "**/*.{js,ts,jsx,tsx}"}
    ]
  ]

Use named profiles for umbrellas or multiple web apps. Apply the same profile to config, watchers, DuskmoonBundler.DevServer, build commands, and runtime helpers:

config :duskmoon_bundler, :my_app_web,
  root: "apps/my_app_web/assets",
  entry: "apps/my_app_web/assets/js/app.js",
  outdir: "apps/my_app_web/priv/static/assets",
  resolve_dirs: ["apps", "deps"],
  tailwind: [
    css: "apps/my_app_web/assets/css/app.css",
    sources: [
      %{base: "apps/my_app_web/lib", pattern: "**/*.{ex,exs,heex}"},
      %{base: "apps/my_app_web/assets", pattern: "**/*.{css,js,ts,jsx,tsx}"}
    ]
  ],
  server: [
    watch_dirs: ["apps/my_app_web/lib", "apps/my_app_web/assets"]
  ]

Use this repository as a local example: config/config.exs defines the :phoenix_duskmoon and :duskmoon_storybook profiles.

Dev Server

Add the dev server plug inside the endpoint's code_reloading? path so it can serve source modules and HMR endpoints in development:

if code_reloading? do
  plug DuskmoonBundler.DevServer, root: "assets"
end

For named profiles, pass the profile and match the prefix to the assets you want the dev server to handle:

if code_reloading? do
  plug DuskmoonBundler.DevServer,
    profile: :my_app_web,
    root: "apps/my_app_web/assets/js",
    prefix: "/assets/js"
end

Start the watcher from config/dev.exs:

config :my_app, MyAppWeb.Endpoint,
  watchers: [
    duskmoon_bundler: {Mix.Tasks.DuskmoonBundler.Dev, :run, [~w(--tailwind)]}
  ]

For a profile watcher:

config :my_app, MyAppWeb.Endpoint,
  watchers: [
    duskmoon_bundler: {Mix.Tasks.DuskmoonBundler.Dev, :run, [["my_app_web"]]}
  ]

Use mix duskmoon_bundler.dev or mix duskmoon_bundler.dev my_app_web when starting the watcher directly.

Layout Tags

Use runtime helpers in layouts instead of hard-coded built filenames:

<link phx-track-static rel="stylesheet" href={DuskmoonBundler.static_path(@endpoint, "/assets/css/app.css")} />
<script defer phx-track-static type="module" src={DuskmoonBundler.static_path(@endpoint, "/assets/js/app.js")}></script>
<%= DuskmoonBundler.Preload.tags(@endpoint, "/assets/js/app.js") %>

Pass profile: :my_app_web for named profile assets:

<script
  defer
  type="module"
  src={DuskmoonBundler.static_path(MyAppWeb.Endpoint, "/assets/js/app.js", profile: :my_app_web)}
>
</script>

duskmoon_bundler_runtime owns these helpers and reads production manifests without starting the dev/build toolchain.

Production Build

Use asset aliases for Phoenix projects:

defp aliases do
  [
    "assets.build": ["duskmoon_bundler.build --tailwind"],
    "assets.deploy": ["duskmoon_bundler.build --tailwind", "phx.digest"]
  ]
end

Build manually when needed:

mix duskmoon_bundler.build
mix duskmoon_bundler.build my_app_web
mix duskmoon_bundler.build my_app_web --tailwind

Common production options:

• Use sourcemap: :hidden or --sourcemap hidden for error tracking without exposing source map URLs.
• Use asset_url_prefix or --asset-url-prefix to change public asset URLs without changing outdir.
• Use public_dir only when intentionally preserving Vite-style public directory behavior.
• Keep hash: true for normal production builds; use hash: false only when a package or fixture needs stable filenames.
• Use external: ~w(phoenix phoenix_html phoenix_live_view) when those packages are provided by the host page.

Formatting And Linting

Register the formatter when JS/TS files should be formatted by mix format:

[
  plugins: [DuskmoonBundler.Formatter],
  inputs: [
    "{mix,.formatter}.exs",
    "{config,lib,test}/**/*.{ex,exs}",
    "assets/**/*.{js,ts,jsx,tsx}"
  ]
]

Configure format and lint behavior in Elixir config:

config :duskmoon_bundler, :format,
  print_width: 100,
  semi: false,
  single_quote: true,
  trailing_comma: :none,
  arrow_parens: :always

config :duskmoon_bundler, :lint,
  plugins: [:typescript],
  rules: %{
    "no-debugger" => :deny,
    "eqeqeq" => :deny
  }

Use these commands:

mix format
mix duskmoon_bundler.js.format
mix duskmoon_bundler.lint
mix duskmoon_bundler.js.check
mix duskmoon_bundler.js.check --type-aware --type-check

Configure config :duskmoon_bundler, :lint, tsgolint: "...", cwd: "..." when type-aware checks need a project-local tsgolint executable.

Validation

After setup or changes, run the smallest checks that prove the edited surface:

mix deps.get
mix npm.install  # when package.json exists or npm deps changed
mix compile --warnings-as-errors
mix format --check-formatted
mix duskmoon_bundler.js.check
mix duskmoon_bundler.build --tailwind

For named profiles, validate the profile explicitly:

mix duskmoon_bundler.build my_app_web --tailwind

When editing this umbrella repository, run commands from the repository root and scope builds to the touched profile when possible, for example:

mix duskmoon_bundler.build phoenix_duskmoon
mix duskmoon_bundler.build duskmoon_storybook

Troubleshooting

If dev assets 404, verify root, prefix, and the requested layout path match. For example, a layout path of /assets/js/app.js usually needs a dev server prefix of /assets/js or a root that makes the requested relative path resolve.

If production helpers cannot find an asset, check that the build wrote manifest.json below the configured outdir and that the layout path matches the original source asset path, such as /assets/js/app.js.

If Tailwind classes are missing, expand the tailwind[:sources] list to include all HEEX, EEx, Elixir, JS, TS, JSX, TSX, Vue, Svelte, or Solid files that contain class names.

If umbrella assets resolve packages incorrectly, set resolve_dirs: ["apps", "deps"] or add the project-specific directories that contain dependencies.

If mix npm.exec cannot find a binary, run mix npm.install first and confirm the package exposes a bin entry under node_modules/.bin/.