Using Google App Engine with Spring Boot Applications

Spring Boot uses Servlet 3.0 APIs to initialize the ServletContext (register Servlets etc.) so you can’t use the same application out of the box in a Servlet 2.5 container. It is however possible to run a Spring Boot application on an older container with some special tools. If you include org.springframework.boot:spring-boot-legacy as a dependency (maintained separately to the core of Spring Boot and currently available at 1.0.2.RELEASE), all you should need to do is create a web.xml and declare a context listener to create the application context and your filters and servlets. The context listener is a special purpose one for Spring Boot, but the rest of it is normal for a Spring application in Servlet 2.5

Visit for more Information: http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#howto-servlet-2-5

Steps

• Depends on spring-boot-legacy (which you will need to build and install locally) as shown below

$ git clone https://github.com/scratches/spring-boot-legacy
$ cd spring-boot-legacy
$ mvn install

• Clone this demo as shown below

$ https://github.com/papicella/GoogleAppEngineSpringBoot.git
$ cd GoogleAppEngineSpringBoot

• Edit the file ./src/main/webapp/WEB-INF/appengine-web.xml to specify the correct APPLICATION ID which we will target in the step below as well.

<?xml version="1.0" encoding="utf-8"?>
<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 <application>fe-papicella</application>
 <version>5</version>
   <threadsafe>true</threadsafe>
 <manual-scaling>
  <instances>1</instances>
 </manual-scaling>
</appengine-web-app>

• Package as shown below

$ mvn package

• Target your project for deployment as follows

pasapicella@pas-macbook:~/piv-projects/GoogleAppEngineSpringBoot$ gcloud projects list
PROJECT_ID              NAME                    PROJECT_NUMBER
bionic-vertex-150302    AppEngineSpringBoot     97889500330
fe-papicella            FE-papicella            1049163203721
pas-spring-boot-on-gcp  Pas Spring Boot on GCP  1043917887789

pasapicella@pas-macbook:~/piv-projects/GoogleAppEngineSpringBoot$ gcloud config set project fe-papicella
Updated property [core/project].

• deploy as follows

$ mvn appengine:deploy

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Pas Apicella [papicella at pivotal.io] is a Senior Platform Architect at Pivotal Australia