google-dwd

Google Domain Wide Delegation Client for Node.js

This library enables Domain-Wide Delegation (DWD) using Service Account credentials without requiring a local private key file. It supports:

• Standard Service Accounts (via GOOGLE_APPLICATION_CREDENTIALS)
• Compute Engine / Cloud Run default service accounts (via Metadata Server)
• Impersonated Credentials

It solves the limitation where standard Google libraries require a local private key for DWD, enabling secure, keyless operation in environments like Cloud Run or GKE.

Install

npm install google-dwd

Usage

const { GoogleAuth } = require('google-auth-library');
const dwd = require('google-dwd');

async function main() {
  // 1. Obtain the initial client (Must be a Service Account, Compute, or Impersonated client)
  const auth = new GoogleAuth({
    scopes: ['https://www.googleapis.com/auth/cloud-platform']
  });
  const client = await auth.getClient();

  // 2. Exchange it for a DWD client acting as a specific user
  const dwdClient = await dwd(
    client, 
    '[email protected]', // The user to impersonate
    ['https://www.googleapis.com/auth/gmail.readonly'] // Scopes required for the user
  );

  // 3. Use the new client to make requests
  const res = await dwdClient.request({ url: 'https://gmail.googleapis.com/gmail/v1/users/me/profile' });
  console.log(res.data);
}

main().catch(console.error);

Supported Credential Types

The client passed to google-dwd must be an instance of one of the following classes from google-auth-library:

• JWT (Standard Service Account key file)
• Compute (Environment-provided credentials on GCE/Cloud Run)
• Impersonated (Short-lived credentials created via IAMCredentials API)

Note: User credentials (e.g., from gcloud auth application-default login) cannot be used directly. However, you can use them to create an Impersonated client (acting as a Service Account), which is supported.

License

Apache-2.0