NOTE: All App Engine users (except Android Studio users - support is not quite ready) are encouraged to transition to the [new gradle plugin] (https://github.com/GoogleCloudPlatform/app-gradle-plugin) for their projects.

Gradle App Engine plugin

The plugin provides tasks for uploading, downloading, running and managing Google App Engine (App Engine) projects in any given Gradle build.

Usage

To use the App Engine plugin, include in your build script:

apply plugin: 'appengine'

The plugin JAR needs to be defined in the classpath of your build script. It is directly available on Maven Central. Alternatively, you can download it from GitHub and deploy it to your local repository. The following code snippet shows an example on how to retrieve it from Maven Central:

buildscript {
  repositories {
    mavenCentral()
  }

  dependencies {
    classpath 'com.google.appengine:gradle-appengine-plugin:1.9.56'
  }
}

Note: The plugin requires you to set the environment variable APPENGINE_HOME or the system property appengine.sdk.root pointing to your current Google App Engine SDK installation. In case you have both variables set the system property takes precedence over the environment variable. Alternatively, you can choose to automatically download the SDK by setting the convention property downloadSdk to true. This option requires you to specify the SDK version you want to use by setting the configuration appengineSdk.

dependencies {
  appengineSdk 'com.google.appengine:appengine-java-sdk:1.9.56'
}

Tasks

The App Engine plugin defines the following tasks:

• appengineConfigureBackends: Dynamically updates settings in backends.xml without having to stop the backend. The setting is defined by the project property setting.
• appengineCronInfo: Verifies and prints the scheduled task (cron) configuration.
• appengineDeleteBackend: Deletes the indicated backend. The backend is defined by the project property backend.
• appengineDownloadApp: Retrieves the most current version of your application.
• appengineDownloadSdk: Downloads and sets Google App Engine SDK.
• appengineEndpointsGetClientLibs: Download Endpoints client libraries. (this makes network calls)
• appengineEndpointsGetDiscoveryDocs: Download Endpoints discovery docs, you should run appengineExplodeApp with this to ensure the discovery docs are copied into the project after download. (this makes network calls)
• appengineEndpointsInstallClientLibraries: Install client libraries to the local maven repo.
• appengineEndpointsExportClientLibraries: Export client libraries to user-defined destination.
• appengineEnhance: Enhances DataNucleus classes by using byte-code manipulation to make your normal Java classes "persistable". This requires you to add the necessary enhancer jars as dependencies to your project.
• appengineExplodeApp: Extends the war/ear task to generate WAR/EAR file and explodes the artifact into build/exploded-app.
• appengineFunctionalTest: Runs the tests from functionalTest source set against a local development server started in daemon mode.
• appengineListBackends: Lists all the backends configured for the app specified in appengine-web.xml.
• appengineLogs: Retrieves log data for the application running on App Engine.
• appengineRollback: Undoes a partially completed update for the given application.
• appengineRollbackBackend: Rolls back a backend update that was interrupted by the user or stopped due to a configuration error. The backend is defined by the project property backend.
• appengineRun: Starts a local development server running your project code. By default the WAR file is created, exploded and used as web application directory each time you run this task. This behavior can be changed by setting the convention property warDir.
• appengineSetDefaultVersion : Sets the default version of the given module based on appengine-web.xml.
• appengineStartBackend: Sets the backend state to START, allowing it to receive HTTP requests. The backend is defined by the project property backend.
• appengineStop: Stops the local development server.
• appengineStopBackend: Sets the backend state to STOP and shuts down any running instances. The backend is defined by the project property backend.
• appengineUpdateAllBackends: Creates or updates all backends configured in backends.xml.
• appengineUpdateBackend: Creates or updates backend configured in backends.xml. The backend is defined by the project property backend.
• appengineUpdateCron: Updates the schedule task (cron) configuration for the app, based on the cron.xml file.
• appengineUpdateDispatch: Updates the dispatch configuration for the app, based on the dispatch.xml file.
• appengineUpdateDos: Updates the DoS protection configuration for the app, based on the dos.xml file.
• appengineUpdateIndexes: Updates datastore indexes in App Engine to include newly added indexes.
• appengineUpdateQueues: Updates the task queue configuration (queue.xml) in App Engine.
• appengineUpdate: Uploads files for an application given the application's root directory. The application ID and version are taken from the appengine-web.xml file.
• appengineUpdateAll: Uploads your application to App Engine and updates all backends by running the task appengineUpdate and appengineUpdateAllBackends.
• appengineVacuumIndexes: Deletes unused indexes in App Engine server.
• appengineVersion: Prints detailed version information about the SDK, Java and the operating system.

Project layout

The App Engine plugin uses the same layout as the Gradle War plugin. The only difference is the addition of the functionalTest source set (located in src/functionalTest by default) which is used by the appengineFunctionalTest task.

Convention properties

The App Engine plugin defines the following convention properties in the appengine closure:

• httpAddress: The IP address for the local development server (if server is to be accessed from network). Default is localhost.
• httpPort: The TCP port which local development server should listen for HTTP requests on (defaults to 8080).
• daemon: Specifies whether the local development server should run in the background. When true, this task completes as soon as the server has started. When false, this task blocks until the local development server is stopped (defaults to false).
• Running the App Engine local development server in daemon mode requires that Gradle is also run as a daemon. The local development server will always be stopped when Gradle exits.
• warDir: Web application directory used for local development server (defaults to build/exploded-war).
• disableUpdateCheck: Disables the Google App Engine update check if set to true.
• jvmFlags: The JVM flags to pass on to the local development server. The data type is a List.
• downloadSdk: Downloads the Google App Engine SDK defined by the configuration name appengineSdk and explodes the artifact into ~/.gradle/appengine-sdk (defaults to false). If set to true the given SDK is used for running all plugin tasks which takes precedence over APPENGINE_HOME and the system property appengine.sdk.root.
• enhancerVersion: The version (v1/v2) parameter for App Engine datanucleus enhancer task Deprecated
• enhancerApi: The api (jdo/jpa) parameter for the App Engine datanucleas enhancer task Deprecated

Within appengine you can define optional properties in a closure named appcfg:

• email: The email address of the Google account of an administrator for the application, for actions that require signing in. If omitted and no cookie is stored from a previous use of the command, the command will prompt for this value.
• server: The App Engine server hostname (defaults to appengine.google.com).
• host: The hostname of the local machine for use with remote procedure calls.
• noCookies: Do not store the administrator sign-in credentials. Prompt for a password every time. (or go through the OAuth2 flow when the oauth2 option is used).
• passIn: Do not store the administrator sign-in credentials as a cookie; prompt for a password every time. If the property password was provided then this value will always be true.
• password: The password in plain text to be used whenever a task requires one. The password is only applied if the email convention property was provided also. Alternatively, you can set the password in your gradle.properties via the property appenginePassword. The password in gradle.properties takes precedence over the one set in this convention property.
• httpProxy: Use the given HTTP proxy to contact App Engine.
• httpsProxy: Use the given HTTPS proxy to contact App Engine, when using HTTPS. If httpProxy is given but httpsProxy is not, both HTTP and HTTPS requests will use the given proxy.
• oauth2: Use OAuth2 authentication instead of password-based authentication.
• extraOptions: A list of extra command line options for the AppCfg tool (defaults to [])

Within appengine you can also define a closure named enhancer:

• version: The version (v1/v2) parameter for App Engine datanucleus enhancer task
• api: The api (jdo/jpa) parameter for the App Engine datanucleas enhancer task
• enhanceOnBuild: Automatically run the enhancer (defaults to false)

Within appengine you can also define a closure named endpoints:

• discoveryDocFormat: A list of discovery doc formats. (defaults to ['rpc', 'rest'])
• serviceClasses: A list of endpoints classes to generate discovery docs or client libs for (overrides values read from web.xml)
• getDiscoveryDocsOnBuild: Automatically download discovery docs before the war task is called. (defaults to false)
• getClientLibsOnBuild: Automatically download client libraries before the war task is called. (defaults to false)
• installClientLibsOnBuild: Automatically install client libs, will get client libs if necessary. (defaults to false) [this task will never be UP-TO-DATE, careful when making part of your build]
• exportClientLibsOnBuild: Automatically export client libs, will get client libs if necessary. (defaults to false)
• clientLibJarOut: Output directory of client library jars when exporting. (Must be of type: File, will be created if doesn't exist)
• clientLibSrcJarOut: Output directory of client library source jars when exporting, if not specified no source jars will be copied. (Must be of type: File, will be created if doesn't exist)
• googleClientVersion: Override the version of the Google Api Client Library that builds with endpoints artifacts. (Only works with endpoints and android-endpoints configurations)

The task appengineDownloadApp requires you to at least define the application ID and directory to write the files to. Define the tasks' properties in the closure app:

• id: The application ID.
• version: The current application version (defaults to current default version).
• outputDirectory: The directory where you wish to save the files (defaults to build/downloaded-app).

The task appengineLogs requires you to at least define the file to write the logs to. Define the tasks' properties in the closure logs:

• numDays: The number of days of log data to retrieve, ending on the current date at midnight UTC. A value of 0 retrieves all available logs. If append is given, then the default is 0, otherwise the default is 1.
• severity: The minimum log level for the log messages to retrieve. The value is a number corresponding to the log level: 4 for CRITICAL, 3 for ERROR, 2 for WARNING, 1 for INFO, 0 for DEBUG. All messages at the given log level and above will be retrieved (defaults to 1 (INFO)).
• append: Tells the plugin to append logs to the log output file instead of overwriting the file. This simply appends the requested data, it does not guarantee the file won't contain duplicate error messages. If this argument is not specified, the plugin will overwrite the log output file.
• includeAll: Include everything in log messages.
• outputFile: The file the logs get written to.

The task appengineUpdate allows you to specify upload specific settings. Define the tasks' properties in the closure update:

• useJava7: Deprecated, has no effect

Example

appengine {
  httpPort = 8085

  appcfg {
    email = 'benjamin.muschko@gmail.com'
      passIn = true

      logs {
        severity = 1
          outputFile = file('mylogs.txt')
      }

    app {
      id = 'sample-app'
    }
  }
}

FAQ

Can I use the plugin with a Gaelyk project?

Gaelyk's template project uses this plugin out-of-the-box so no additional configuration needs to be done. If you start your project from scratch and decide to use the plugin please refer to the following sections to configure it properly.

Gaelyk <= 1.1

Yes, you just have to configure the WAR plugin to point to the correct web application (by default war) and source code (by default src) directory. If you want to stick to the default source directory simply create the subdirectory src/main/groovy.

apply plugin: 'groovy'

sourceSets {
    main {
        groovy {
            srcDirs = ['src']
        }
    }
}

webAppDirName = file('war')

When editing a Groovlets/Groovy templates in Gaelyk the server automatically deploys the change and you see it take effect almost instantly. The plugin provides support for that. Simply set the warDir convention property and leave the server running.

appengine {
    warDir = file('war')
}

Gaelyk >= 1.2

Starting with version 1.2 Gaelyk adopted Gradle's default directory structure. The following changes are required to leverage Gaelyk's hot-reloading feature.

appengine {
    warDir = file('src/main/webapp')
}

sourceSets.main.output.classesDir = 'src/main/webapp/WEB-INF/classes'

**How do I remote debug the local development server?**

You can use the convention property jvmFlags to set the JVM debug parameters. Make sure to set the TCP port you want your JVM to listen on. The following example show how to set the JVM flags to listen on port 8000.

appengine {
    jvmFlags = ['-Xdebug', '-Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000']
}

How do I use OAuth2 passwordless login to authenticate?

You can configure your app to use OAuth2 with the option

appengine {
    appcfg {
        oauth2 = true
    }
}

For more details on the authentication flow see App Engine OAuth2 docs

**How do I run functional tests on the local development server?**

If you want to execute your tests in the container alongside the rest of your application you have to configure the appengineRun task to run in daemon mode. Starting with version 0.7 of the plugin this has become even easier. It provides the task appengineFunctionalTest which lets you define your functional test dependencies via the configuration functionalTestCompile. On top of that the task has been fully integrated into the build lifecycle.

One of the most prominent functional testing libraries in the Groovy ecosystem is Geb, an expressive and powerful browser automation solution. Please refer to this short and sweet tutorial for a quickstart.

**Why is my exploded-war still using old discovery docs even though I ran appengineEndpointsGetDisoveryDocs?**

The task appengineEndpointsGetDiscoveryDocs only downloads the Discovery Docs for an endpoint to a cache in build/discovery-docs, the war task copies this into the WEB-INF folder when packaging. If you want them to be copied in, just run build or appengineExplodeApp again. Why do we do this? The endpoints calls are network calls to a service and some users may not want to do this on every build. The user can update their endpoints discovery docs when they know they need to and it will be packaged in on every subsequent build without needing to be regenerated.

**How do I use a compile dependency on my endpoints client libraries from another project?**

Using the new configurations in the appengine plugin (endpoints/android-endpoints) you can do

 dependencies {
     compile project(path: '<appengine-module>', configuration: 'endpoints')
 }

or in an android project

dependencies {
    compile project(path: '<appengine-module>', configuration: 'android-endpoints')
}

**Enhancer failed with "Java returned: 1", how do I know what's wrong?**

Run using the --info flag when building to find the location of the error log file, that log file might have details on what went wrong. On linux machines it may appear as "/tmp/enhance(some number).log"

**How do I deploy with gcloud?**

If you're using gcloud to deploy your application, the newest version of app deploy doesn't support war directories, you will need to provide it with an app.yaml OR you can use the appengineStage task to create a directory that is deployable in <project>/build/staged-app

$ ./gradlew appengineStage
$ gcloud app deploy build/staged-app/app.yaml --project [app id] --version [some version]

NOTES:

• You must explicitly define all config files your want to upload (cron.yaml, etc)
• This does not work with EAR formatted projects.

**How do I create client libraries for iOS?**

You can generate a discovery document for your Api using the appengineEndpointsGetDiscoveryDocs task. Discovery documents can then be found in the <project>/build/discovery-docs directory. Follow the iOS endpoints instructions to create client libraries for your iOS application.