Most of the functionality provided by the App Engine bundled services is now provided by the Cloud Client Libraries for Java. For more information, see the recommended alternatives listed below.
If migrating to an unbundled solution is not an option for your project, then you may be able to continue using legacy bundled services in your Java 11/17 apps as a fallback. This approach gives you flexibility to move to unbundled services later in the migration cycle.
You can use Firestore in Datastore mode as an alternative to the Datastore API that is bundled with the Java 8 runtime. Firestore is the newest version of Datastore, and we recommend Datastore mode for databases that will be used primarily by App Engine apps.
You can serve images from Cloud Storage, serve them directly, or use a third-party content delivery network (CDN).
To resize, convert, and manipulate images, use an image processing library such as ImageJ2, imgscalr, or thumbnailator To use one of these third-party libraries, add the library as a dependency and update your code to call the library's APIs.
The App Engine Images service also provided functionality to avoid dynamic requests to your application by handling image resizing using a serving URL. If you want similar functionality, you can generate the re-sized images ahead of time and upload them to Cloud Storage for serving. Alternatively, you could use a third-party content delivery network (CDN) service that offers image resizing.
We recommend that you update your app to use Cloud Logging, which supports features such as viewing logs in the Logs Explorer, downloading logs, filtering messages by severity, and correlating app messages with specific requests. As an alternative, you can enable these features by writing log messages that contain specific data structured in a JSON object. For more information, see Writing and viewing logs.
To cache application data, use Memorystore for Redis.
To obtain information and modify your application's running services, use a combination of environment variables and the App Engine Admin API:
|Service information||How to access|
|Current application ID||
|Current project ID||
|Current service name||
|Current service version||
|Current instance ID||
|Default hostname||Admin API
|List of services||Admin API
|List of versions for a service||Admin API
|Default version for a service, including any traffic splits||Admin API
|List of running instances for a version||Admin API
The Namespaces API enabled multitenant apps to partition data across tenants simply by specifying a unique namespace string for each tenant.
While Datastore supports multitenancy directly, other Google Cloud services do not. If your multitenant app uses other Google Cloud services, you will need to handle multitenancy manually. To have completely isolated instances of services, you can create new projects programmatically using the Cloud Resource Manager API and access resources across projects.
Host any full-text search database such as Elasticsearch on Compute Engine and access it from your service.
Queue tasks for asynchronous code execution using the Cloud Tasks REST API, RPC API, or the Google Cloud Client library, and use a Java 11/17 App Engine standard service as a Push target. For more information, see Migrating from Task Queues to Cloud Tasks.
In many cases where you might use pull queues, such as queuing up tasks or messages that will be pulled and processed by separate workers, Pub/Sub can be a good alternative as it offers similar functionality and delivery guarantees.
For Java 11/17, see the following sample program interacting with the Cloud Tasks API.
For an alternative to the Users API, use any HTTP-based authentication mechanism such as:
- OAuth 2.0 and OpenID Connect which provide federated identity from the provider of your choice. Google is an OpenID Connect identity provider. There are also several other providers available. For Java 11/17, this sample implements an OAuth 2.0 flow using the Google OAuth Client Library for Java.
- Firebase Authentication, which provides authentication using username/password and federated identity using Google, Facebook, Twitter, and more.
- Google Identity Platform, which provides many options for authentication and authorization of Google user accounts.
- Auth0, which provides authentication with various identity providers and single sign-on features.