Using Gradle and the App Engine Plugin

This page explains how to manage an App Engine flexible environment project using Gradle, a flexible build automation system that is declarative and is used to automate build, testing, publishing, and deployment.

Before you begin

Installing the App Engine Java SDK

To use App Engine Gradle tasks, you must install the App Engine Java SDK:

gcloud components install app-engine-java

Configuring Google Cloud SDK

Initialize gcloud and log in:

gcloud init

If you've already initialized gcloud:

  • To authorize the user account without performing setup steps, run gcloud auth login

  • To access Google resources from your project when running locally, set the application default credentials by running gcloud beta auth application-default login.

Creating a new 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:

  1. Create a new directory and navigate to it.

  2. To initialize a new project:

    gradle init --type java-library;
    mkdir -p src/main/webapp/WEB-INF;
    mkdir -p src/main/appengine
  3. Remove the stub files generated by gradle init:

    rm src/main/java/ src/test/java/
  4. Add the following to your build.gradle file to add App Engine Gradle tasks, Maven repositories, the App Engine Gradle plugin, dependencies, and task configuration:

    buildscript {      // Configuration for building
      repositories {
        jcenter()      // Bintray's repository - a fast Maven Central mirror & more
      dependencies {
        classpath ''
        classpath 'org.akhikhl.gretty:gretty:+'
    repositories {   // repositories for JARs you access in your code
      maven {
        url ''             // Google's mirror of Maven Central
    //maven {
    //  url '' // SNAPSHOT repository if needed
    apply plugin: 'java'
    apply plugin: 'war'
    apply plugin: 'org.akhikhl.gretty'
    apply plugin: ''
    dependencies {
      providedCompile 'javax.servlet:javax.servlet-api:3.1.0'
      providedCompile ''
    // Add your dependencies here.
    gretty {
        port = 8080
        contextPath = '/'
        servletContainer = 'jetty9'  // What App Engine Flexible uses
    appengine {
      deploy {   // deploy configuration
        stopPreviousVersion = true  // default - stop the current version
        promote = true              // default - & make this the current version
    group = 'com.example.appengine'   // Generated output GroupId
    version = '1.0-SNAPSHOT'          // Version in generated output
    sourceCompatibility = 1.8
    targetCompatibility = 1.8

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

See the quickstart for an overview of a Java App Engine project.

Downloading the Hello World app

  1. Clone the Hello World sample app repository to your local machine:

    git clone

    Alternatively, you can download the sample as a zip file and extract it.

  2. Change to the directory that contains the sample code:

    cd java-docs-samples/appengine/helloworld-new-plugins

Testing your application with the development server

  1. Change to the root of your application directory.

  2. 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.

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

    :processResources UP-TO-DATE
    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/

  4. See your app running at http://localhost:8080.

To learn more about the Gretty plugin, see Gretty Configuration and Gretty tasks.

Deploying 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.

Using the compat runtime

The Java 8 /Jetty 9 Compat runtime is compatible with the App Engine standard environment APIs, and is identified by having a src/main/webapp/WEB-INF/appengine-web.xml file that specifies <vm>true<\vm>. For compat runtimes, the Gradle plugin behaves as it does in the App Engine standard environment. For more details, see Using Gradle in the standard environment and Tasks and Properties in the standard environment.

Instead of gradle jettyRun to test your application, you can run the App Engine development server with:

gradle appengineRun

Using the Gradle wrapper

Gradle provides a mechanism to download and run the required version of Gradle without installation:

Mac OS X and Linux

./gradlew jettyRun


gradlew.bat jettyRun

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

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