Google Auth Library

Open source authentication client library for Java.

• API Documentation

This project consists of 3 artifacts:

• google-auth-library-credentials: contains base classes and interfaces for Google credentials
• google-auth-library-appengine: contains App Engine credentials. This artifact depends on the App Engine SDK.
• google-auth-library-oauth2-http: contains a wide variety of credentials as well as utility methods to create them and to get Application Default Credentials

Note: This client is a work-in-progress, and may occasionally make backwards-incompatible changes.

Quickstart

If you are using Maven, add this to your pom.xml file (notice that you can replace google-auth-library-oauth2-http with any of google-auth-library-credentials and google-auth-library-appengine, depending on your application needs):

<dependency>
  <groupId>com.google.auth</groupId>
  <artifactId>google-auth-library-oauth2-http</artifactId>
  <version>0.22.2</version>
</dependency>

If you are using Gradle, add this to your dependencies

compile 'com.google.auth:google-auth-library-oauth2-http:0.22.2'

If you are using SBT, add this to your dependencies

libraryDependencies += "com.google.auth" % "google-auth-library-oauth2-http" % "0.22.2"

google-auth-library-credentials

This artifact contains base classes and interfaces for Google credentials:

• Credentials: base class for an authorized identity. Implementations of this class can be used to authorize your application
• RequestMetadataCallback: interface for the callback that receives the result of the asynchronous Credentials.getRequestMetadata(URI, Executor, RequestMetadataCallback)
• ServiceAccountSigner: interface for a service account signer. Implementations of this class are capable of signing byte arrays using the credentials associated to a Google Service Account

google-auth-library-appengine

This artifact depends on the App Engine SDK (appengine-api-1.0-sdk) and should be used only by applications running on App Engine environments that use urlfetch. The AppEngineCredentials class allows you to authorize your App Engine application given an instance of AppIdentityService.

Usage:

import com.google.appengine.api.appidentity.AppIdentityService;
import com.google.appengine.api.appidentity.AppIdentityServiceFactory;
import com.google.auth.Credentials;
import com.google.auth.appengine.AppEngineCredentials;

AppIdentityService appIdentityService = AppIdentityServiceFactory.getAppIdentityService();

Credentials credentials =
    AppEngineCredentials.newBuilder()
        .setScopes(...)
        .setAppIdentityService(appIdentityService)
        .build();

Important: com.google.auth.appengine.AppEngineCredentials is a separate class from com.google.auth.oauth2.AppEngineCredentials.

google-auth-library-oauth2-http

Application Default Credentials

This artifact contains a wide variety of credentials as well as utility methods to create them and to get Application Default Credentials. Credentials classes contained in this artifact are:

• CloudShellCredentials: credentials for Google Cloud Shell built-in service account
• ComputeEngineCredentials: credentials for Google Compute Engine built-in service account
• OAuth2Credentials: base class for OAuth2-based credentials
• ServiceAccountCredentials: credentials for a Service Account - use a JSON Web Token (JWT) to get access tokens
• ServiceAccountJwtAccessCredentials: credentials for a Service Account - use JSON Web Token (JWT) directly in the request metadata to provide authorization
• UserCredentials: credentials for a user identity and consent

To get Application Default Credentials use GoogleCredentials.getApplicationDefault() or GoogleCredentials.getApplicationDefault(HttpTransportFactory). These methods return the Application Default Credentials which are used to identify and authorize the whole application. The following are searched (in order) to find the Application Default Credentials:

1. Credentials file pointed to by the GOOGLE_APPLICATION_CREDENTIALS environment variable
2. Credentials provided by the Google Cloud SDK gcloud auth application-default login command
3. Google App Engine built-in credentials
4. Google Cloud Shell built-in credentials
5. Google Compute Engine built-in credentials
   • Skip this check by setting the environment variable NO_GCE_CHECK=true
   • Customize the GCE metadata server address by setting the environment variable GCE_METADATA_HOST=<hostname>

Explicit Credential Loading

To get Credentials from a Service Account JSON key use GoogleCredentials.fromStream(InputStream) or GoogleCredentials.fromStream(InputStream, HttpTransportFactory). Note that the credentials must be refreshed before the access token is available.

GoogleCredentials credentials = GoogleCredentials.fromStream(new FileInputStream("/path/to/credentials.json"));
credentials.refreshIfExpired();
AccessToken token = credentials.getAccessToken();
// OR
AccessToken token = credentials.refreshAccessToken();

ImpersonatedCredentials

Allows a credentials issued to a user or service account to impersonate another. The source project using ImpersonatedCredentials must enable the "IAMCredentials" API. Also, the target service account must grant the orginating principal the "Service Account Token Creator" IAM role.

String credPath = "/path/to/svc_account.json";
ServiceAccountCredentials sourceCredentials = ServiceAccountCredentials
     .fromStream(new FileInputStream(credPath));
sourceCredentials = (ServiceAccountCredentials) sourceCredentials
    .createScoped(Arrays.asList("https://www.googleapis.com/auth/iam"));

ImpersonatedCredentials targetCredentials = ImpersonatedCredentials.create(sourceCredentials,
    "[email protected]", null,
    Arrays.asList("https://www.googleapis.com/auth/devstorage.read_only"), 300);

Storage storage_service = StorageOptions.newBuilder().setProjectId("project-id")
    .setCredentials(targetCredentials).build().getService();

for (Bucket b : storage_service.list().iterateAll())
    System.out.println(b); 

Configuring a Proxy

For HTTP clients, a basic proxy can be configured by using http.proxyHost and related system properties as documented by Java Networking and Proxies.

For a more custom proxy (e.g. for an authenticated proxy), provide a custom HttpTransportFactory to GoogleCredentials:

import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.apache.v2.ApacheHttpTransport;
import com.google.auth.http.HttpTransportFactory;
import com.google.auth.oauth2.GoogleCredentials;
import org.apache.http.HttpHost;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.CredentialsProvider;
import org.apache.http.client.HttpClient;
import org.apache.http.conn.routing.HttpRoutePlanner;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.client.ProxyAuthenticationStrategy;
import org.apache.http.impl.conn.DefaultProxyRoutePlanner;

import java.io.IOException;

public class ProxyExample {
  public GoogleCredentials getCredentials() throws IOException {
    HttpTransportFactory httpTransportFactory = getHttpTransportFactory(
        "some-host", 8080, "some-username", "some-password"
    );

    return GoogleCredentials.getApplicationDefault(httpTransportFactory);
  }

  public HttpTransportFactory getHttpTransportFactory(String proxyHost, int proxyPort, String proxyUsername, String proxyPassword) {
    HttpHost proxyHostDetails = new HttpHost(proxyHost, proxyPort);
    HttpRoutePlanner httpRoutePlanner = new DefaultProxyRoutePlanner(proxyHostDetails);

    CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
    credentialsProvider.setCredentials(
        new AuthScope(proxyHostDetails.getHostName(), proxyHostDetails.getPort()),
        new UsernamePasswordCredentials(proxyUsername, proxyPassword)
    );

    HttpClient httpClient = ApacheHttpTransport.newDefaultHttpClientBuilder()
        .setRoutePlanner(httpRoutePlanner)
        .setProxyAuthenticationStrategy(ProxyAuthenticationStrategy.INSTANCE)
        .setDefaultCredentialsProvider(credentialsProvider)
        .build();

    final HttpTransport httpTransport = new ApacheHttpTransport(httpClient);
    return new HttpTransportFactory() {
      @Override
      public HttpTransport create() {
        return httpTransport;
      }
    };
  }
}

The above example requires com.google.http-client:google-http-client-apache-v2.

Using Credentials with google-http-client

Credentials provided by google-auth-library can be used with Google's HTTP-based clients. We provide a HttpCredentialsAdapter which can be used as an HttpRequestInitializer.

import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.services.bigquery.Bigquery;
import com.google.auth.http.HttpCredentialsAdapter;
import com.google.auth.oauth2.GoogleCredentials;

GoogleCredentials credentials = GoogleCredentials.getApplicationDefault();
HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(credentials);

Bigquery bq = new Bigquery.Builder(HTTP_TRANSPORT, JSON_FACTORY, requestInitializer)
    .setApplicationName(APPLICATION_NAME)
    .build();

Verifying JWT Tokens (Beta)

To verify a JWT token, use the TokenVerifier class.

Verifying a Signature

To verify a signature, use the default TokenVerifier:

import com.google.api.client.json.webtoken.JsonWebSignature;
import com.google.auth.oauth2.TokenVerifier;

TokenVerifier tokenVerifier = TokenVerifier.newBuilder().build();
try {
  JsonWebSignature jsonWebSignature = tokenVerifier.verify(tokenString);
  // optionally verify additional claims
  if (!"expected-value".equals(jsonWebSignature.getPayload().get("additional-claim"))) {
    // handle custom verification error
  }
} catch (TokenVerifier.VerificationException e) {
  // invalid token
}

Customizing the TokenVerifier

To customize a TokenVerifier, instantiate it via its builder:

import com.google.api.client.json.webtoken.JsonWebSignature;
import com.google.auth.oauth2.TokenVerifier;

TokenVerifier tokenVerifier = TokenVerifier.newBuilder()
  .setAudience("audience-to-verify")
  .setIssuer("issuer-to-verify")
  .build();
try {
  JsonWebSignature jsonWebSignature = tokenVerifier.verify(tokenString);
  // optionally verify additional claims
  if (!"expected-value".equals(jsonWebSignature.getPayload().get("additional-claim"))) {
    // handle custom verification error
  }
} catch (TokenVerifier.VerificationException e) {
  // invalid token
}

For more options, see the TokenVerifier.Builder documentation.

CI Status

Java Version	Status
Java 7
Java 8
Java 8 OSX
Java 8 Windows
Java 11

Contributing

Contributions to this library are always welcome and highly encouraged.

See CONTRIBUTING documentation for more information on how to get started.

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms. See Code of Conduct for more information.

Running the Tests

To run the tests you will need:

• Maven 3+

$ mvn test

License

BSD 3-Clause - See LICENSE for more information.