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CC 4.0 License

The content of this section is derived from the content of the following links and is subject to the CC BY 4.0 license.

The following contents can be assumed to be the result of modifications and deletions based on the original contents if not specifically stated.

EnvironmentPlugin

The EnvironmentPlugin is shorthand for using the DefinePlugin on process.env keys.

Options

  • Type: string[] | Record<string, string>

Examples

Basic Use Case

The EnvironmentPlugin accepts either an array of keys or an object mapping its keys to their default values.

new rspack.EnvironmentPlugin(['NODE_ENV', 'DEBUG']);

This is equivalent to the following DefinePlugin application:

new rspack.DefinePlugin({
  'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV),
  'process.env.DEBUG': JSON.stringify(process.env.DEBUG),
});
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Not specifying the environment variable raises an "EnvironmentPlugin - ${key} environment variable is undefined" error.

Usage with default values

Alternatively, the EnvironmentPlugin supports an object, which maps keys to their default values. The default value for a key is taken if the key is undefined in process.env.

new rspack.EnvironmentPlugin({
  NODE_ENV: 'development', // use 'development' unless process.env.NODE_ENV is defined
  DEBUG: false,
});
WARNING

Variables coming from process.env are always strings.

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Unlike DefinePlugin, default values are applied to JSON.stringify by the EnvironmentPlugin.

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Default values of null and undefined behave differently. Use undefined for variables that must be provided during bundling, or null if they are optional.

WARNING

If an environment variable is not found during bundling and no default value was provided, Rspack will throw an error instead of a warning.

Let's investigate the result when running the previous EnvironmentPlugin configuration on a test file entry.js:

if (process.env.NODE_ENV === 'production') {
  console.log('Welcome to production');
}
if (process.env.DEBUG) {
  console.log('Debugging output');
}

When executing NODE_ENV=production Rspack in the terminal to build, entry.js becomes this:

if ('production' === 'production') {
  // <-- 'production' from NODE_ENV is taken
  console.log('Welcome to production');
}
if (false) {
  // <-- default value is taken
  console.log('Debugging output');
}

Running DEBUG=false Rspack yields:

if ('development' === 'production') {
  // <-- default value is taken
  console.log('Welcome to production');
}
if ('false') {
  // <-- 'false' from DEBUG is taken
  console.log('Debugging output');
}

Git Version

The following EnvironmentPlugin configuration provides process.env.GIT_VERSION (such as "v5.4.0-2-g25139f57f") and process.env.GIT_AUTHOR_DATE (such as "2020-11-04T12:25:16+01:00") corresponding to the last Git commit of the repository:

const child_process = require('child_process');
function git(command) {
  return child_process.execSync(`git ${command}`, { encoding: 'utf8' }).trim();
}

new rspack.EnvironmentPlugin({
  GIT_VERSION: git('describe --always'),
  GIT_AUTHOR_DATE: git('log -1 --format=%aI'),
});

DotenvPlugin

The third-party DotenvPlugin (dotenv-webpack) allows you to expose (a subset of) dotenv variables:

// .env
DB_HOST=127.0.0.1
DB_PASS=foobar
S3_API=mysecretkey
new Dotenv({
  path: './.env', // Path to .env file (this is the default)
  safe: true, // load .env.example (defaults to "false" which does not use dotenv-safe)
});