Gradle is an open-source build automation tool focused on flexibility and performance. App Engine provides a Gradle plugin that you can use to build and deploy your app to App Engine. The code samples in this guide use Gradle version 8.
Before you begin
If you haven't already done so, follow the steps in this guide to download the gcloud CLI, create your Google Cloud project, and initialize your App Engine app.
Install the gcloud CLI
app-engine-java
component:gcloud components install app-engine-java
Create a new Gradle project
You can create a new Gradle project from scratch using the shell. Alternatively, to try out the plugin, you can download, run locally, and deploy the hello world project.
To create a new project:
Create a new directory and navigate to it.
To initialize a new project:
Run
gradle init
:gradle init --type java-application
You'll be asked to answer questions:
- Enter target Java version (min: 7, default: 21): 21
- Select application structure: 1 for Single application project
- Select build script DSL: 2 (for Groovy)
- Select test framework: 1 (for JUnit 4)
- Generate build using new APIs and behavior: no
Create the
WEB-INF
folder:mkdir -p app/src/main/webapp/WEB-INF
Create the
appengine
folder:mkdir -p app/src/main/appengine
Remove the stub files generated by
gradle init
:rm ./app/src/main/java/org/example/App.java ./app/src/test/java/org/example/AppTest.java
Add the following to your
app/build.gradle
file to add App Engine Gradle tasks, Maven repositories, the App Engine Gradle plugin, dependencies, and task configuration:You also need to add the following files to your project, using a text editor or integrated development environment (IDE):
- app/src/main/docker/Dockerfile (optional for custom runtimes)
- Java classes
- Java testing classes
See Set up your development environment for an overview of a Java App Engine project.
Download the Hello World app
Clone the Hello World sample app repository to your local machine:
git clone https://github.com/GoogleCloudPlatform/java-docs-samples.git
Alternatively, you can download the sample as a zip file and extract it.
Change to the directory that contains the sample code:
cd java-docs-samples/flexible/java-8/helloworld
Testing your application with the development server
To access Google resources from your project when running locally, set the application default credentials by running:
gcloud auth application-default login
Change to the root of your application directory.
During the development phase, you can run and test your application at any time in the development server by invoking Gradle:
gradle jettyRun
Alternatively, you can run Gradle without installing it by using the Gradle wrapper.
Wait for the server to start. The server is started with your application running when you see a message similar to this:
:prepareInplaceWebAppFolder :createInplaceWebAppFolder :compileJava :processResources UP-TO-DATE :classes :prepareInplaceWebAppClasses :prepareInplaceWebApp :jettyRun 17:40:05 INFO Jetty 9.2.15.v20160210 started and listening on port 8080 17:40:05 INFO runs at: 17:40:05 INFO http://localhost:8080/
See your app running at
http://localhost:8080
.
To learn more about the Gretty plugin, see Gretty Configuration and Gretty tasks.
Deploy your application
To deploy your application:
gradle appengineDeploy
The appengineDeploy
task and all other Gradle tasks have associated properties
that you can use. For a complete list of tasks and properties, refer to
App Engine Gradle Tasks and Properties.
Use the Gradle wrapper
Gradle provides a mechanism to download and run the required version of Gradle without installation:
Linux/macOS
Change to the sample code directory.
Run gradlew:
./gradlew jettyRun
Windows
Change to the sample code directory.
Run gradlew:
./gradlew.bat jettyRun
Additional information on Gradle can be found in App Engine Gradle Tasks and Properties.
What's next
- Explore the plugin code and report issues on GitHub.
- Learn how to specify properties for tasks by referring to App Engine Gradle Tasks and Properties.