JarCastingGoogle Cloud Java Client Libraries
Java idiomatic client for Google Cloud Platform services.
Supported APIs
Libraries are available on GitHub and Maven Central for developing Java applications that interact with individual Google Cloud services:
If the service is not listed, google-api-java-client interfaces with additional Google Cloud APIs using a legacy REST interface.
When building Java applications, preference should be given to the libraries listed in the table.
Specifying a Project ID
Most google-cloud libraries require a project ID. There are multiple ways to specify this project ID.
- When using
google-cloudlibraries from within Compute/App Engine, there's no need to specify a project ID. It is automatically inferred from the production environment. - When using
google-cloudelsewhere, you can do one of the following:
- Supply the project ID when building the service options. For example, to use Datastore from a project with ID "PROJECT_ID", you can write:
Datastore datastore = DatastoreOptions.newBuilder().setProjectId("PROJECT_ID").build().getService();
- Specify the environment variable
GOOGLE_CLOUD_PROJECTto be your desired project ID. - Set the project ID using the Google Cloud SDK. To use the SDK, download the SDK if you haven't already, and set the project ID from the command line. For example:
gcloud config set project PROJECT_ID
google-cloud determines the project ID from the following sources in the listed order, stopping once it finds a value:
- The project ID supplied when building the service options
- Project ID specified by the environment variable
GOOGLE_CLOUD_PROJECT - The App Engine / Compute Engine project ID
- The project ID specified in the JSON credentials file pointed by the
GOOGLE_APPLICATION_CREDENTIALSenvironment variable - The Google Cloud SDK project ID
In cases where the library may expect a project ID explicitly, we provide a helper that can provide the inferred project ID:
import com.google.cloud.ServiceOptions;
...
String projectId = ServiceOptions.getDefaultProjectId();
Authentication
google-cloud-java uses https://github.com/googleapis/google-auth-library-java to authenticate requests. google-auth-library-java supports a wide range of authentication types; see the project's README and javadoc for more details.
Google Cloud Platform environment
When using Google Cloud libraries from a Google Cloud Platform environment such as Compute Engine, Kubernetes Engine, or App Engine, no additional authentication steps are necessary.
For example:
Storage storage = StorageOptions.getDefaultInstance().getService();
or:
CloudTasksClient cloudTasksClient = CloudTasksClient.create();
Other environments
Using a service account (recommended)
-
After downloading that key, you must do one of the following:
- Define the environment variable GOOGLE_APPLICATION_CREDENTIALS to be the location of the key. For example:
export GOOGLE_APPLICATION_CREDENTIALS=/path/to/my/key.json- Supply the JSON credentials file when building the service options. For example, this Storage object has the necessary permissions to interact with your Google Cloud Storage data:
Storage storage = StorageOptions.newBuilder() .setCredentials(ServiceAccountCredentials.fromStream(new FileInputStream("/path/to/my/key.json"))) .build() .getService();
Local development/testing
If running locally for development/testing, you can use the Google Cloud SDK. Create Application Default Credentials with gcloud auth application-default login, and then google-cloud will automatically detect such credentials.
Existing OAuth2 access token
If you already have an OAuth2 access token, you can use it to authenticate (notice that in this case, the access token will not be automatically refreshed):
Credentials credentials = GoogleCredentials.create(new AccessToken(accessToken, expirationTime));
Storage storage = StorageOptions.newBuilder()
.setCredentials(credentials)
.build()
.getService();
or:
Credentials credentials = GoogleCredentials.create(new AccessToken(accessToken, expirationTime));
CloudTasksSettings cloudTasksSettings = CloudTasksSettings.newBuilder()
.setCredentialProvider(FixedCredentialsProvider.create(credentials))
.build();
CloudTasksClient cloudTasksClient = CloudTasksClient.create(cloudTasksSettings);
Application Default Credentials
If no credentials are provided, google-cloud will attempt to detect them from the environment using GoogleCredentials.getApplicationDefault() which will search for Application Default Credentials in the following locations (in order):
- The credentials file pointed to by the
GOOGLE_APPLICATION_CREDENTIALSenvironment variable - Credentials provided by the Google Cloud SDK
gcloud auth application-default logincommand - Google App Engine built-in credentials
- Google Cloud Shell built-in credentials
- Google Compute Engine built-in credentials
Troubleshooting
To get help, follow the instructions in the Troubleshooting document.
Configuring a Proxy
HTTP Clients
For HTTP clients, a proxy can be configured by using http.proxyHost, https.proxyHost, and related system properties as documented by Java Networking and Proxies.
gRPC Clients
For gRPC clients, a proxy can be configured by using the GRPC_PROXY_EXP environment variable as documented by the gRPC release notes. Please note that gRPC proxy support is currently experimental.
For a more custom proxy, you will need supply a ProxyDetector to the ManagedChannelBuilder:
import com.google.api.core.ApiFunction;
import com.google.api.gax.rpc.TransportChannelProvider;
import com.google.cloud.tasks.v2.CloudTasksClient;
import com.google.cloud.tasks.v2.CloudTasksSettings;
import com.google.cloud.tasks.v2.stub.CloudTasksStubSettings;
import io.grpc.HttpConnectProxiedSocketAddress;
import io.grpc.ManagedChannelBuilder;
import io.grpc.ProxiedSocketAddress;
import io.grpc.ProxyDetector;
import javax.annotation.Nullable;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
public CloudTasksClient getService() throws IOException {
TransportChannelProvider transportChannelProvider =
CloudTasksStubSettings.defaultGrpcTransportProviderBuilder()
.setChannelConfigurator(
new ApiFunction<ManagedChannelBuilder, ManagedChannelBuilder>() {
@Override
public ManagedChannelBuilder apply(ManagedChannelBuilder managedChannelBuilder) {
return managedChannelBuilder.proxyDetector(
new ProxyDetector() {
@Nullable
@Override
public ProxiedSocketAddress proxyFor(SocketAddress socketAddress)
throws IOException {
return HttpConnectProxiedSocketAddress.newBuilder()
.setUsername(PROXY_USERNAME)
.setPassword(PROXY_PASSWORD)
.setProxyAddress(new InetSocketAddress(PROXY_HOST, PROXY_PORT))
.setTargetAddress((InetSocketAddress) socketAddress)
.build();
}
});
}
})
.build();
CloudTasksSettings cloudTasksSettings =
CloudTasksSettings.newBuilder()
.setTransportChannelProvider(transportChannelProvider)
.build();
return CloudTasksClient.create(cloudTasksSettings);
}
Long Running Operations
Long running operations (LROs) are often used for API calls that are expected to take a long time to complete (e.g. provisioning a GCE instance or a Dataflow pipeline). The initial API call creates an "operation" on the server and returns an operation ID to track its progress.
Our generated gRPC clients provide a nice interface for starting the operation and then waiting for the operation to complete. This is accomplished by returning an OperationFuture. When you call get() on the OperationFuture we poll the operation endpoint to check on the operation. These polling operations have a default timeout that varies from service to service and will throw a java.util.concurrent.CancellationException with the message: Task was cancelled. after that timeout has been reached.
Configuring LRO Timeouts
ClusterControllerSettings.Builder settingsBuilder = ClusterControllerSettings.newBuilder();
TimedRetryAlgorithm timedRetryAlgorithm = OperationTimedPollAlgorithm.create(
RetrySettings.newBuilder()
.setInitialRetryDelay(Duration.ofMillis(500L))
.setRetryDelayMultiplier(1.5)
.setMaxRetryDelay(Duration.ofMillis(5000L))
.setInitialRpcTimeout(Duration.ZERO) // ignored
.setRpcTimeoutMultiplier(1.0) // ignored
.setMaxRpcTimeout(Duration.ZERO) // ignored
.setTotalTimeout(Duration.ofHours(24L)) // set polling timeout to 24 hours
.build());
settingsBuilder.createClusterOperationSettings()
.setPollingAlgorithm(timedRetryAlgorithm);
ClusterControllerClient clusterControllerClient = ClusterControllerClient.create(settingsBuilder.build());
Managing Dependencies
If you are using more than one Google Cloud client library, we recommend you use one of our Bill of Material (BOM) artifacts to help manage dependency versions. For more information, see https://github.com/GoogleCloudPlatform/cloud-opensource-java/wiki/The-Google-Cloud-Platform-Libraries-BOM.
Java Versions
Java 7 or above is required for using the clients in this repository.
Supported Platforms
Clients in this repository use either HTTP or gRPC for the transport layer. All HTTP-based clients should work in all environments.
For clients that use gRPC, the supported platforms are constrained by the platforms that Forked Tomcat Native supports, which for architectures means only x86_64, and for operating systems means Mac OS X, Windows, and Linux. Additionally, gRPC constrains the use of platforms with threading restrictions.
Thus, the following are not supported:
- Android
- Consider Firebase, which includes many of these APIs.
- It is possible to use these libraries in many cases, although it is unsupported. You can find examples, such as this one, in this example repository but consider the risks carefully before using these libraries in an application.
- Raspberry Pi (since it runs on the ARM architecture)
- Google App Engine Standard Java 7
The following environments should work (among others):
- standalone Windows on x86_64
- standalone Mac OS X on x86_64
- standalone Linux on x86_64
- Google Compute Engine (GCE)
- Google Container Engine (GKE)
- Google App Engine Standard Java 8 (GAE Std J8)
- Google App Engine Flex (GAE Flex)
- Alpine Linux (Java 11+)
Testing
This library provides tools to help write tests for code that uses google-cloud services.
See TESTING to read more about using our testing helpers.
Versioning
This library follows Semantic Versioning, with some additional qualifications:
-
Components marked with
@BetaApior@Experimentalare considered to be "0.x" features inside a "1.x" library. This means they can change between minor and patch releases in incompatible ways. These features should not be used by any library "B" that itself has consumers, unless the components of library B that use@BetaApifeatures are also marked with@BetaApi. Features marked as@BetaApiare on a path to eventually become "1.x" features with the marker removed.Special exception for google-cloud-java: google-cloud-java is allowed to depend on
@BetaApifeatures in gax-java without declaring the consuming code@BetaApi, because gax-java and google-cloud-java move in step with each other. For this reason, gax-java should not be used independently of google-cloud-java. -
Components marked with
@InternalApiare technically public, but only because of the limitations of Java's access modifiers. For the purposes of semver, they should be considered private. -
Interfaces marked with
@InternalExtensionOnlyare public, but should only be implemented by internal classes. For the purposes of semver, we reserve the right to add to these interfaces without default implementations (for Java 7).
Please note these clients are currently under active development. Any release versioned 0.x.y is subject to backwards incompatible changes at any time.
GA
Libraries defined at a GA quality level are expected to be stable and all updates in the libraries are guaranteed to be backwards-compatible. Any backwards-incompatible changes will lead to the major version increment (1.x.y -> 2.0.0).
Beta
Libraries defined at a Beta quality level are expected to be mostly stable and we're working towards their release candidate. We will address issues and requests with a higher priority.
Alpha
Libraries defined at an Alpha quality level are still a work-in-progress and are more likely to get backwards-incompatible updates. Additionally, it's possible for Alpha libraries to get deprecated and deleted before ever being promoted to Beta or GA.
IDE Plugins
If you're using IntelliJ or Eclipse, you can add client libraries to your project using these IDE plugins:
Besides adding client libraries, the plugins provide additional functionality, such as service account key management. Refer to the documentation for each plugin for more details.
These client libraries can be used on App Engine standard for Java 8 runtime and App Engine flexible (including the Compat runtime). Most of the libraries do not work on the App Engine standard for Java 7 runtime. However, Datastore, Storage, and Bigquery should work.
Contributing
Contributions to this library are always welcome and highly encouraged.
See google-cloud's CONTRIBUTING documentation and the shared 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.
License
Apache 2.0 - See LICENSE for more information.
