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 deployyour app to App Engine.Note: For information about other ways to build and deploy your app, seeTesting and deploying your app.

Before you begin

1. Install Java

2. Install Gradle

3. Install git

4. If you haven't already done so, follow the steps in thisguideto download the gcloud CLI, create your Google Cloud project, andinitialize your App Engine app.

5. Install the gcloud CLIapp-engine-java component:

   gcloudcomponentsinstallapp-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 deploythe hello world project.

To create a new project:

1. Create a new directory and navigate to it.

2. To initialize a new project:

   1. Rungradle init:

      gradleinit--typejava-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

   2. Create theWEB-INF folder:

      mkdir-papp/src/main/webapp/WEB-INF

   3. Create theappengine folder:

      mkdir-papp/src/main/appengine

3. Remove the stub files generated bygradle init:

   rm./app/src/main/java/org/example/App.java./app/src/test/java/org/example/AppTest.java

4. Add the following to yourapp/build.gradle file to add App EngineGradle tasks, Maven repositories, the App Engine Gradle plugin,dependencies, and task configuration:

   applyplugin:'java'applyplugin:'war'buildscript{repositories{// gretty plugin is in Maven CentralmavenCentral()}dependencies{classpath'com.google.cloud.tools:appengine-gradle-plugin:2.8.1'classpath'org.gretty:gretty:4.1.5'}}applyplugin:'org.gretty'applyplugin:'com.google.cloud.tools.appengine'repositories{mavenCentral()}appengine{deploy{// deploy configurationstopPreviousVersion=true// default - stop the current versionpromote=true// default - & make this the current versionprojectId='GCLOUD_CONFIG'version='GCLOUD_CONFIG'}}sourceSets{// In Gradle 8, the default location is app/src/java, which does not match// Maven's directory structure.main.java.srcDirs=['src/main/java']main.resources.srcDirs=['src/main/resources','src/main/webapp']test.java.srcDirs=['src/test/java']}dependencies{implementation'com.google.appengine:appengine-api-1.0-sdk:2.0.30'implementation'jakarta.servlet:jakarta.servlet-api:6.1.0'// Test DependenciestestImplementation'com.google.appengine:appengine-testing:2.0.30'testImplementation'com.google.appengine:appengine-api-stubs:2.0.30'testImplementation'com.google.appengine:appengine-tools-sdk:2.0.30'testImplementation'com.google.truth:truth:1.1.5'testImplementation'junit:junit:4.13.2'testImplementation'org.mockito:mockito-core:4.11.0'}

5. You also need to add the following files to your project, using a texteditor or integrated development environment (IDE):

   • app/src/main/appengine/app.yaml

   • app/src/main/docker/Dockerfile (optional forcustom runtimes)
   • Java classes
   • Javatesting classes

SeeSet up your development environment for anoverview of a Java App Engine project.

Testing your application with the development server

1. To access Google resources from your project when running locally,set the application default credentials by running:

   gcloudauthapplication-defaultlogin

2. Change to the root of your application directory.

3. During the development phase, you can run and test your application at anytime in the development server by invoking Gradle:

   gradlejettyRun

   Alternatively, you can run Gradle without installing it byusing the Gradle wrapper.

4. Wait for the server to start. The server is started with yourapplication running when you see a message similar to this:

   :prepareInplaceWebAppFolder:createInplaceWebAppFolder:compileJava:processResources UP-TO-DATE:classes:prepareInplaceWebAppClasses:prepareInplaceWebApp:jettyRun17:40:05 INFO  Jetty 9.2.15.v20160210 started and listening on port 808017:40:05 INFO   runs at:17:40:05 INFO    http://localhost:8080/

5. See your app running athttp://localhost:8080.

To learn more about theGretty plugin,seeGretty Configuration andGretty tasks.

Deploy your application

To deploy your application:

gradleappengineDeploy

TheappengineDeploy task and all other Gradle tasks have associated propertiesthat you can use. For a complete list of tasks and properties, refer toApp Engine Gradle Tasks and Properties.

Use the Gradle wrapper

Gradle provides a mechanism to download and run the required version of Gradlewithout installation:

Additional information on Gradle can be found inApp Engine Gradle Tasks and Properties.

What's next

• Explore the plugin code and report issues onGitHub.
• Learn how to specify properties for tasks by referring toApp Engine Gradle Tasks and Properties.