rollup-plugin-node-externals

A Rollup plugin that automatically declares NodeJS built-in modules as external. Can also handle npm dependencies, devDependencies, peerDependencies and optionalDependencies.

Why?

By default, Rollup doesn't know a thing about NodeJS, so trying to bundle simple things like import * as path from 'path' in your code generates an Unresolved dependencies error. The solution here is twofold, depending on what you're building:

• If building a standalone app, e.g. for the browser, you'll need to use some kind of shim like those provided by rollup-plugin-node-builtins.
• If building an npm module or lib, you'll need to tell Rollup that the path module is in fact external: this way, Rollup won't try to bundle the module in and rather leave the import statement as is (or translate it to a require() call if bundling for CommonJS).

However, this must be done for each and every NodeJS built-in: path, os, fs, etc., which can quicky become cumbersome when done manually. So the primary goal of this plugin is simply to automatically declare all NodeJS built-in modules as external.

This plugin will also allow you to declare your dependencies (as declared in your package.json file) as external. This may come in handy when building an Electron app, for example.

Install

npm install --save-dev rollup-plugin-node-externals

Usage

import externals from 'rollup-plugin-node-externals'

export default {
  // ...
  plugins: [
    externals({
      // The path to your package.json. Optional. Default: process.cwd() which is usally the same dir where rollup.config.js stands
      packagePath: 'path/to/package.json',

      // Make node built-ins external. Optional. Default: true
      builtins: true,

      // Make pkg.dependencies external. Optional. Default: false
      deps: false,

      // Make pkg.peerDependencies external. Optional. Default: true
      peerDeps: true,

      // Make pkg.optionalDependencies external. Optional. Default: true
      optDeps: true,

      // Make pkg.devDependencies external. Optional. Default: true
      devDeps: true,

      // Modules to exclude from externals. Optional. Default: none
      exclude: [],

      // Modules to include in externals. Optional. Default: all
      include: [],

      // Deprecated -- see below
      except: []
    })
  ]
}

Most of the time, the built-in defaults are just what you need:

import externals from 'rollup-plugin-node-externals'
// ...

export default {
  // ...
  plugins: [
    externals(),        // Bundle deps in; make Node built-ins, devDeps, peerDeps and optDeps external
  ]
}

Note: the list of builtins is obtained via the builtin-modules package, by Sindre Sorhus and should be up-to-date with your current NodeJS version.

Note: if you're also using rollup-plugin-node-resolve, make sure this plugin comes before it in the plugins array:

import externals from 'rollup-plugin-node-externals'
import resolve from 'rollup-plugin-node-resolve'
// ...

export default {
  // ...
  plugins: [
    externals(),
    resolve(),
    // other plugins
  ]
}

Options

By default, the plugin will mark all Node built-in modules and all your dev-, peer- and optionalDependencies as external. Normal dependencies are left unmarked so Rollup will still bundle them with your code as expected in most situations.

• Set the deps, devDeps, peerDeps and/or optDeps options to false to prevent the corresponding dependencies from being externalized, therefore letting Rollup bundle them with your code. Set them to true for Rollup to treat the corresponding dependencies as external.

• Use the exclude option to remove certain dependencies from the list of externals. exclude can be a string, a regex, or an array of those, for example:

externals({
    deps: true,             // Don't bundle dependencies, we'll require() them at runtime instead
    exclude: [
        'electron-reload',  // Yet we want `electron-reload` bundled in
        /^vuex?/            // as well as the VueJS family (vue, vuex, vue-router, etc.)
    ]
})

• Use the include option to force certain dependencies into the list of externals, for example:

externals({
    peerDeps: false,        // Bundle peerDependencies in
    include: /^lodash/      // Except for Lodash
})

Just like exclude, the include option can be a string, a regex or an array of those.

Note: this plugin uses an exact match against your imports, so if your are using some path substitution in your code, eg.:

// in your code:
import something from '@/mylib'   // Say '@/' is mapped to some directory
...

and you don't want mylib bundled in, then write:

// in rollup.config.js:
externals({
    include: '@/mylib'            // /^@\// or /mylib$/ would work too
})

Migrating from version 1.x

• In 1.x, normal dependencies were externalized by default. This is no more true, so you'll need to change:

externals()

to:

externals({ deps: true })

if you want the same behavior.

• For consistency with all other Rollup plugins out there, the except option from 1.x is now deprecated in favor of the Rollup-friendly exclude option. except is still accepted for backward compatibility and works exactly the same as exclude but it will issue a warning if used. To suppress this warning, just replace except with exclude.

Licence

MIT