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>0.24.0</version>
</dependency>

If you are using Gradle, add this to your dependencies

compile 'com.google.auth:google-auth-library-oauth2-http:0.24.0'

If you are using SBT, add this to your dependencies

libraryDependencies += "com.google.auth" % "google-auth-library-oauth2-http" % "0.24.0"

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 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
ExternalAccountCredentials: base class for credentials using workload identity federation to access Google Cloud resources from non-Google Cloud platforms
IdentityPoolCredentials: credentials using workload identity federation to access Google Cloud resources from Microsoft Azure or any identity provider that supports OpenID Connect (OIDC)
AwsCredentials: credentials using workload identity federation to access Google Cloud resources from Amazon Web Services (AWS)

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:

Credentials file pointed to by the GOOGLE_APPLICATION_CREDENTIALS environment variable
Credentials provided by the Google Cloud SDK gcloud auth application-default login command
Google App Engine built-in credentials
Google Cloud Shell built-in credentials
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,
    "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);

Workload Identity Federation

Using workload identity federation, your application can access Google Cloud resources from Amazon Web Services (AWS), Microsoft Azure, or any identity provider that supports OpenID Connect (OIDC).

Traditionally, applications running outside Google Cloud have used service account keys to access Google Cloud resources. Using identity federation, your workload can impersonate a service account. This lets the external workload access Google Cloud resources directly, eliminating the maintenance and security burden associated with service account keys.

Accessing resources from AWS

In order to access Google Cloud resources from Amazon Web Services (AWS), the following requirements are needed:

A workload identity pool needs to be created.
AWS needs to be added as an identity provider in the workload identity pool (the Google organization policy needs to allow federation from AWS).
Permission to impersonate a service account needs to be granted to the external identity.

Follow the detailed instructions on how to configure workload identity federation from AWS.

After configuring the AWS provider to impersonate a service account, a credential configuration file needs to be generated. Unlike service account credential files, the generated credential configuration file contains non-sensitive metadata to instruct the library on how to retrieve external subject tokens and exchange them for service account access tokens. The configuration file can be generated by using the gcloud CLI.

To generate the AWS workload identity configuration, run the following command:

# Generate an AWS configuration file.
gcloud iam workload-identity-pools create-cred-config \
    projects/$PROJECT_NUMBER/locations/global/workloadIdentityPools/$POOL_ID/providers/$AWS_PROVIDER_ID \
    --service-account $SERVICE_ACCOUNT_EMAIL \
    --aws \
    --output-file /path/to/generated/config.json

Where the following variables need to be substituted:

$PROJECT_NUMBER: The Google Cloud project number.
$POOL_ID: The workload identity pool ID.
$AWS_PROVIDER_ID: The AWS provider ID.
$SERVICE_ACCOUNT_EMAIL: The email of the service account to impersonate.

This generates the configuration file in the specified output file.

You can now use the Auth library to call Google Cloud resources from AWS.

Access resources from Microsoft Azure

In order to access Google Cloud resources from Microsoft Azure, the following requirements are needed:

A workload identity pool needs to be created.
Azure needs to be added as an identity provider in the workload identity pool (the Google organization policy needs to allow federation from Azure).
The Azure tenant needs to be configured for identity federation.
Permission to impersonate a service account needs to be granted to the external identity.

Follow the detailed instructions on how to configure workload identity federation from Microsoft Azure.

After configuring the Azure provider to impersonate a service account, a credential configuration file needs to be generated. Unlike service account credential files, the generated credential configuration file contains non-sensitive metadata to instruct the library on how to retrieve external subject tokens and exchange them for service account access tokens. The configuration file can be generated by using the gcloud CLI.

To generate the Azure workload identity configuration, run the following command:

# Generate an Azure configuration file.
gcloud iam workload-identity-pools create-cred-config \
    projects/$PROJECT_NUMBER/locations/global/workloadIdentityPools/$POOL_ID/providers/$AZURE_PROVIDER_ID \
    --service-account $SERVICE_ACCOUNT_EMAIL \
    --azure \
    --output-file /path/to/generated/config.json

Where the following variables need to be substituted:

$PROJECT_NUMBER: The Google Cloud project number.
$POOL_ID: The workload identity pool ID.
$AZURE_PROVIDER_ID: The Azure provider ID.
$SERVICE_ACCOUNT_EMAIL: The email of the service account to impersonate.

This generates the configuration file in the specified output file.

You can now use the Auth library to call Google Cloud resources from Azure.

Accessing resources from an OIDC identity provider

In order to access Google Cloud resources from an identity provider that supports OpenID Connect (OIDC), the following requirements are needed:

A workload identity pool needs to be created.
An OIDC identity provider needs to be added in the workload identity pool (the Google organization policy needs to allow federation from the identity provider).
Permission to impersonate a service account needs to be granted to the external identity.

Follow the detailed instructions on how to configure workload identity federation from an OIDC identity provider.

After configuring the OIDC provider to impersonate a service account, a credential configuration file needs to be generated. Unlike service account credential files, the generated credential configuration file contains non-sensitive metadata to instruct the library on how to retrieve external subject tokens and exchange them for service account access tokens. The configuration file can be generated by using the gcloud CLI.

For OIDC providers, the Auth library can retrieve OIDC tokens either from a local file location (file-sourced credentials) or from a local server (URL-sourced credentials).

File-sourced credentials For file-sourced credentials, a background process needs to be continuously refreshing the file location with a new OIDC token prior to expiration. For tokens with one hour lifetimes, the token needs to be updated in the file every hour. The token can be stored directly as plain text or in JSON format.

To generate a file-sourced OIDC configuration, run the following command:

# Generate an OIDC configuration file for file-sourced credentials.
gcloud iam workload-identity-pools create-cred-config \
    projects/$PROJECT_NUMBER/locations/global/workloadIdentityPools/$POOL_ID/providers/$OIDC_PROVIDER_ID \
    --service-account $SERVICE_ACCOUNT_EMAIL \
    --credential-source-file $PATH_TO_OIDC_ID_TOKEN \
    # Optional arguments for file types. Default is "text":
    # --credential-source-type "json" \
    # Optional argument for the field that contains the OIDC credential.
    # This is required for json.
    # --credential-source-field-name "id_token" \
    --output-file /path/to/generated/config.json

Where the following variables need to be substituted:

$PROJECT_NUMBER: The Google Cloud project number.
$POOL_ID: The workload identity pool ID.
$OIDC_PROVIDER_ID: The OIDC provider ID.
$SERVICE_ACCOUNT_EMAIL: The email of the service account to impersonate.
$PATH_TO_OIDC_ID_TOKEN: The file path used to retrieve the OIDC token.

This generates the configuration file in the specified output file.

URL-sourced credentials For URL-sourced credentials, a local server needs to host a GET endpoint to return the OIDC token. The response can be in plain text or JSON. Additional required request headers can also be specified.

To generate a URL-sourced OIDC workload identity configuration, run the following command:

# Generate an OIDC configuration file for URL-sourced credentials.
gcloud iam workload-identity-pools create-cred-config \
    projects/$PROJECT_NUMBER/locations/global/workloadIdentityPools/$POOL_ID/providers/$OIDC_PROVIDER_ID \
    --service-account $SERVICE_ACCOUNT_EMAIL \
    --credential-source-url $URL_TO_GET_OIDC_TOKEN \
    --credential-source-headers $HEADER_KEY=$HEADER_VALUE \
    # Optional arguments for file types. Default is "text":
    # --credential-source-type "json" \
    # Optional argument for the field that contains the OIDC credential.
    # This is required for json.
    # --credential-source-field-name "id_token" \
    --output-file /path/to/generated/config.json

Where the following variables need to be substituted:

$PROJECT_NUMBER: The Google Cloud project number.
$POOL_ID: The workload identity pool ID.
$OIDC_PROVIDER_ID: The OIDC provider ID.
$SERVICE_ACCOUNT_EMAIL: The email of the service account to impersonate.
$URL_TO_GET_OIDC_TOKEN: The URL of the local server endpoint to call to retrieve the OIDC token.
$HEADER_KEY and $HEADER_VALUE: The additional header key/value pairs to pass along the GET request to $URL_TO_GET_OIDC_TOKEN, e.g. Metadata-Flavor=Google.

You can now use the Auth library to call Google Cloud resources from an OIDC provider.

Using External Identities

External identities (AWS, Azure, and OIDC-based providers) can be used with Application Default Credentials. In order to use external identities with Application Default Credentials, you need to generate the JSON credentials configuration file for your external identity as described above. Once generated, store the path to this file in the GOOGLE_APPLICATION_CREDENTIALS environment variable.

export GOOGLE_APPLICATION_CREDENTIALS=/path/to/config.json

The library can now choose the right type of client and initialize credentials from the context provided in the configuration file.

GoogleCredentials googleCredentials = GoogleCredentials.getApplicationDefault();

String projectId = "your-project-id";
String url = "https://storage.googleapis.com/storage/v1/b?project=" + projectId;

HttpCredentialsAdapter credentialsAdapter = new HttpCredentialsAdapter(googleCredentials);
HttpRequestFactory requestFactory = new NetHttpTransport().createRequestFactory(credentialsAdapter);
HttpRequest request = requestFactory.buildGetRequest(new GenericUrl(url));

JsonObjectParser parser = new JsonObjectParser(GsonFactory.getDefaultInstance());
request.setParser(parser);

HttpResponse response = request.execute();
System.out.println(response.parseAsString());

You can also explicitly initialize external account clients using the generated configuration file.

ExternalAccountCredentials credentials = 
    ExternalAccountCredentials.fromStream(new FileInputStream("/path/to/credentials.json"));

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.

blead/google-auth-library-java

Google Auth Library

Quickstart

google-auth-library-credentials

google-auth-library-appengine

google-auth-library-oauth2-http

Application Default Credentials

Explicit Credential Loading

ImpersonatedCredentials

Workload Identity Federation

Accessing resources from AWS

Access resources from Microsoft Azure

Accessing resources from an OIDC identity provider

Using External Identities

Configuring a Proxy

Using Credentials with google-http-client

Verifying JWT Tokens (Beta)

Verifying a Signature

Customizing the TokenVerifier

CI Status

Contributing

Running the Tests

License

Using Credentials with `google-http-client`