# `Volt.Config`
[🔗](https://github.com/elixir-volt/volt/blob/v0.16.0/lib/volt/config.ex#L1)

Read Volt configuration from application environment.

## Flat config (single app)

All config lives under the `:volt` application key in `config/config.exs`:

    # config/config.exs
    config :volt,
      entry: "assets/js/app.ts",
      target: :es2020,
      external: ~w(phoenix phoenix_html phoenix_live_view),
      aliases: %{
        "@" => "assets/src",
        "@components" => "assets/src/components"
      },
      plugins: [],
      tailwind: [
        css: "assets/css/app.css",
        sources: [
          %{base: "lib/", pattern: "**/*.{ex,heex}"},
          %{base: "assets/", pattern: "**/*.{vue,ts,tsx}"}
        ]
      ]

    # config/dev.exs
    config :volt, :server,
      prefix: "/assets",
      watch_dirs: ["lib/"]

## Named profiles (umbrella / multi-web apps)

Use a named profile to configure multiple independent Volt instances:

    # config/config.exs
    config :volt, :my_app_web,
      entry: "apps/my_app_web/assets/js/app.js",
      outdir: "apps/my_app_web/priv/static/assets",
      tailwind: [
        css: "apps/my_app_web/assets/css/app.css",
        sources: [
          %{base: "apps/my_app_web/lib/", pattern: "**/*.{ex,heex,eex}"}
        ]
      ],
      server: [watch_dirs: ["apps/my_app_web/lib/"]]

Pass the profile name to Mix tasks and the plug:

    mix volt.build my_app_web --tailwind
    mix volt.dev my_app_web --tailwind

    plug Volt.DevServer, root: "assets", profile: :my_app_web

CLI flags and plug options override config values.

## Source maps

The `:sourcemap` option controls production source map generation:

  * `true` — write `.map` files and append `//# sourceMappingURL` (default)
  * `:hidden` — write `.map` files but omit the URL comment (for error tracking services)
  * `false` — no source maps

## Tree shaking

Production builds tree-shake JavaScript by default. Set `tree_shaking: false`
to preserve unused exports.

## Environment variables

The `:env_prefix` option controls which `.env` variables are exposed to
client code through `import.meta.env`. It defaults to `"VOLT_"` and accepts a
string or list of strings.

## Asset URL prefix

The `:asset_url_prefix` option controls the public URL prefix emitted for
production asset references in JavaScript and CSS. It defaults to `"/assets"`,
matching Phoenix's conventional `priv/static/assets` mount.

## Manual chunks

The `:chunks` option controls manual chunk splitting:

    config :volt,
      chunks: %{
        "vendor" => ["vue", "vue-router", "pinia"],
        "ui" => ["assets/src/components"]
      }

Bare specifiers match package names in node_modules. Path patterns match
against the full module path.

## tsconfig.json paths

Volt automatically reads `compilerOptions.paths` from `tsconfig.json` in
the project root and merges them into aliases. Explicitly configured
aliases take precedence over tsconfig paths.

# `build`

```elixir
@spec build(atom() | keyword()) :: map()
```

Read the full build config, merged with defaults.

Accepts an optional profile atom as the first argument. When given, reads
from `Application.get_env(:volt, profile)` and merges it on top of flat
config and defaults.

`overrides` (from CLI flags or function opts) take precedence over all
config sources.

Automatically reads `compilerOptions.paths` from `tsconfig.json` and
merges them into aliases. Explicit aliases override tsconfig paths.

# `build`

```elixir
@spec build(
  atom() | nil,
  keyword()
) :: map()
```

# `server`

```elixir
@spec server(atom() | keyword()) :: map()
```

Read dev server config, merged with defaults.

When a profile is given, reads the `:server` key from within that profile's
config, falling back to the global `:server` config.

# `server`

```elixir
@spec server(
  atom() | nil,
  keyword()
) :: map()
```

# `tailwind`

```elixir
@spec tailwind(atom() | nil) :: keyword()
```

Read Tailwind config.

When a profile is given, reads the `:tailwind` key from within that
profile's config, falling back to the global `:tailwind` config.

---

*Consult [api-reference.md](api-reference.md) for complete listing*