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>0.16.0</version>
</dependency>

If you are using Gradle, add this to your dependencies

compile 'com.google.auth:google-auth-library-oauth2-http:0.16.0'

If you are using SBT, add this to your dependencies

libraryDependencies += "com.google.auth" % "google-auth-library-oauth2-http" % "0.16.0"

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. The AppEngineCredentials class allows you to authorize your App Engine application given an instance of AppIdentityService.

You can install the App Engine SDK from Maven Central:

$ mvn dependency:get -Dartifact=com.google.appengine:appengine-api-1.0-sdk:1.9.71

You can find all available versions on Maven Central.

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 ImpersonaedCredentials 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,
    "impersonated-account@project.iam.gserviceaccount.com", 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); 

CI Status

Java Version	Status
Java 7
Java 8
Java 8 OSX
Java 8 Windows
Java 10

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+
• App Engine SDK (see installation instructions above)

$ mvn install -DskipTests=true
$ mvn test

License

BSD 3-Clause - See LICENSE for more information.