sbt / sbt-appengine

deploy your webapp to Google App Engine using sbt.

Version Matrix

sbt-appengine is a sbt 0.10+ port of the awesome Yasushi/sbt-appengine-plugin.


export environment variables (JREBEL_PATH is optional).

export APPENGINE_SDK_HOME=/Applications/appengine-java-sdk-
export JREBEL_PATH=/Applications/ZeroTurnaround/JRebel/jrebel.jar

If you have problems setting the APPENGINE_SDK_HOME environment variable (for example if you're using IntelliJ), then you can instead create a file with a single line of sdkHome=/Applications/appengine-java-sdk-

setup for sbt 0.13 and sbt 1.x

put the following in the project/appengine.sbt:

addSbtPlugin("com.eed3si9n" % "sbt-appengine" % "0.8.0")

and the following in appengine.sbt:

libraryDependencies += "org.mortbay.jetty" % "jetty" % "6.1.22" % "container"


setup for sbt 0.12




you can deploy your application like this:

> appengineDeploy

development server

to (re)start the development server in the background:

> appengineDevServer

to redeploy development server continuously:

> ~ appengineDevServer

hot loading!

to hot reload development server continuously, set JREBEL_PATH and:

> appengineDevServer
> ~ packageWar

by default development server runs in debug mode. IDE can connect to it via port 1044.

appengineDevServer lifecyle hooks

to run a code on start/stop of dev server:

(appengineOnStartHooks in appengineDevServer in Compile) += { () =>

(appengineOnStopHooks in appengineDevServer in Compile) += { () =>

backend support

you can deploy your backend application(s) like this:

> appengineDeployBackends

to start a backend instance in the cloud:

> appengineStartBackend <backend-name>

to stop a backend instance:

> appengineStopBackend <backend-name>

DataNucleous enhancer support (experimental)

sbt-appengine provides experimental support for DataNucleous enhancer. to use this, include the following in build.sbt:



appenginePersistenceApi in appengineEnhance in Compile := "JDO"

this will call the enhancer automatically on packageWar task. since DataNucleous expects plain Java fields, the entity class looks a bit ugly in Scala:

import javax.jdo.annotations._
import scala.annotation.meta.field

case class Counter(
  @(PrimaryKey @field)
  @(Persistent @field)(valueStrategy = IdGeneratorStrategy.IDENTITY)
  var key: Key,
  @(Persistent @field)
  var count: Int)



When trying to launch the dev server with appengineDevServer, you might run into the following exception: java.lang.RuntimeException: Unable to restore the previous TimeZone. This issue has been resolved in the latest App Engine SDK.