Dart

Get Google Cloud Storage Access Token using Service Account JSON Private Key

See more Google Cloud Storage Examples

Demonstrates how to get a Google Cloud Storage access token using a JSON service account private key. Obtaining an access token for a service account requires no user interaction (it does not require a browser, nor callback URI's, etc.).

When an access token expires, an application can be (and should be) designed to automatically fetch a new access token.

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  // First load the JSON key into a string.
  final fac = CkFileAccess();
  final String jsonKey;
  try {
    jsonKey = fac.readEntireTextFile('qa_data/googleApi/ChilkatCloud-13a07a2e8b3f.json', 'utf-8');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // A JSON private key should look something like this:

  // 	{
  // 	  "type": "service_account",
  // 	  "project_id": "chilkattest-1350",
  // 	  "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
  // 	  "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
  // 	  "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
  // 	  "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
  // 	  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
  // 	  "token_uri": "https://accounts.google.com/o/oauth2/token",
  // 	  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
  // 	  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
  // 	}

  final gAuth = CkAuthGoogle();
  gAuth.jsonKey = jsonKey;

  // Choose a scope.
  gAuth.scope = 'https://www.googleapis.com/auth/cloud-platform';

  // Request an access token that is valid for this many seconds.
  gAuth.expireNumSeconds = 3600;

  // If the application is requesting delegated access:
  // The email address of the user for which the application is requesting delegated access,
  // then set the email address here. (Otherwise leave it empty.)
  gAuth.subEmailAddress = '';

  // Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
  // The Chilkat socket object is used so that the connection can be established
  // through proxies or an SSH tunnel if desired.
  final tlsSock = CkSocket();
  try {
    tlsSock.connect('www.googleapis.com', 443, true, 5000);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Send the request to obtain the access token.
  try {
    gAuth.obtainAccessToken(tlsSock);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Examine the access token:
  print('Access Token: ${gAuth.accessToken}');

  // We're going to save this access token to a file to be used
  // by other examples.
  final sbToken = CkStringBuilder();
  sbToken.append(gAuth.accessToken);
  sbToken.writeFile('qa_data/tokens/googleCloudStorageAccessToken.txt', 'utf-8', false);
}