rollup-license-plugin

Manage third-party license compliance in your rollup and vite builds

Key Features • Installation • How to use • Available options • Examples

Key features

This plugin extracts open source license information about all of the npm/yarn/pnpm packages in your rollup or vite output and helps you identify and fix problems with your open source licensing policy.

• Discover every node_module used in your rollup or vite build
• Find out how it is licensed
• Cancel builds that include unacceptable licenses
• Exclude internal packages from being scanned
• Create a customized inventory (usually called bill of materials) in json, html, csv or other formats

Installation

Install rollup-license-plugin as a development dependency to your current project:

npm install -D rollup-license-plugin

How to use

Use rollup-license-plugin in your rollup or vite configuration by adding it to the plugins array.

Rollup

import { createRollupLicensePlugin } from 'rollup-license-plugin';

export default {
  plugins: [
    createRollupLicensePlugin()
  ]
}

Vite

import { defineConfig } from 'vite'
import { createViteLicensePlugin } from 'rollup-license-plugin'

export default defineConfig({
  plugins: [
    createViteLicensePlugin()
  ],
})

Further code examples will only show createRollupLicensePlugin, but they are applicable to Vite aswell by importing createViteLicensePlugin instead.

Available options

Options are given as an Object to the createRollupLicensePlugin and createViteLicensePlugin methods:

createViteLicensePlugin({
  outputFilename: 'thirdPartyNotice.json'
})

The available options are:

Name	Description
additionalFiles	Default: {}. Object that defines additional files that should be generated by this plugin based on it's default output (e.g. an html representation of the licenses in addition to the generated json). Keys represent filenames, values are functions that get invoked with the packages array and should return the content written to the additional file. These functions can be async or return a Promise.
excludedPackageTest	A method to exclude packages from the process. It is invoked with packageName (string) and version (string) of every package and should return true to exclude the package.
licenseOverrides	Default: {}. Object with licenses to override. Keys have the format <name>@<version>, values are valid spdx license expressions. This can be helpful when license information is inconclusive and has been manually checked.
outputFilename	Default: oss-licenses.json. Path to the output file that will be generated. Relative to the bundle output directory.
replenishDefaultLicenseTexts	Default: false. When this is enabled, default license texts are taken from spdx.org for packages where no license text was found.
unacceptableLicenseTest	A method to define license identifiers as unacceptable. It is invoked with licenseIdentifier (string) for every package and should return true when the license is unacceptable and encountering it should fail the build.
includePackages	Default: () => []. A method to define packages that should always be included in the output. It must return an array containing the absolute paths of those packages. This function can be async or return a Promise.

Example with custom options

This example writes the result to a file named meta/licenses.json in the output directory, fails whenever it encounters one of the given licenses and overrides the license of the package fuse.js@3.2.1.

createRollupLicensePlugin({
  excludedPackageTest: (packageName, version) => {
    return packageName.startsWith('@internal/')
  },
  licenseOverrides: {
    // has "Apache" in package.json, but Apache-2.0 text in LICENSE file
    'fuse.js@3.2.1': 'Apache-2.0'
  },
  outputFilename: 'meta/licenses.json',
  unacceptableLicenseTest: (licenseIdentifier) => {
    return ['GPL', 'AGPL', 'LGPL', 'NGPL'].includes(licenseIdentifier)
  }
})

Default output

The output is a oss-licenses.json file in the rollup or vite build output directory. It contains an array of packages that were found to be part of the build output and lists several license-related details for every package:

Name	Description
name	package name
version	package version
author	author listed in package.json (if available)
repository	repository url listed in package.json (if available)
source	package tarball url on npm registry
license	the license listed in package.json. If this is not a valid spdx license expression, this plugin will inform you. You can then inform the package maintainers about this problem and temporarily workaround this issue with the licenseOverrides option for the specific combination of package name and version.
licenseText	the license text read from a file matching /^licen[cs]e/i in the package's root

Example output file

[
  {
    "name": "fbjs",
    "version": "0.8.17",
    "repository": "https://github.com/facebook/fbjs",
    "source": "https://registry.npmjs.org/fbjs/-/fbjs-0.8.17.tgz",
    "license": "MIT",
    "licenseText": "..."
  },
  {
    "name": "object-assign",
    "version": "4.1.1",
    "author": "Sindre Sorhus",
    "repository": "https://github.com/sindresorhus/object-assign",
    "source": "https://registry.npmjs.org/object-assign/-/object-assign-4.1.1.tgz",
    "license": "MIT",
    "licenseText": "..."
  },
  {
    "name": "react-dom",
    "version": "16.4.2",
    "repository": "https://github.com/facebook/react",
    "source": "https://registry.npmjs.org/react-dom/-/react-dom-16.4.2.tgz",
    "license": "MIT",
    "licenseText": "..."
  },
  {
    "name": "react",
    "version": "16.4.2",
    "repository": "https://github.com/facebook/react",
    "source": "https://registry.npmjs.org/react/-/react-16.4.2.tgz",
    "license": "MIT",
    "licenseText": "..."
  }
]

Examples

additionalFiles examples

When the additionalFiles option is set, the output shown above is passed into the transform function as an array for every additional file configured.

This way, the output can be formatted to any format you might need and then be written to one or more additional files.

Package list as CSV

createRollupLicensePlugin({
  additionalFiles: {
    'oss-licenses.csv': (packages) => {
      const keys = ['name', 'version', 'license']
      return [
        '"sep=,"',
        keys.join(','),
        ...packages.map(p => keys.map(key => `="${p[key]}"`).join(',')),
      ].join('\n')
    }
  }
})

Package list and additional summary

createRollupLicensePlugin({
  additionalFiles: {
    'oss-summary.json': packages => {
      const licenseCount = packages.reduce(
        (prev, { license }) => ({
          ...prev,
          [license]: prev[license] ? prev[license] + 1 : 1,
        }),
        {}
      )
      return JSON.stringify(licenseCount, null, 2)
    },
  },
})