Deploying a Spring Boot application on Google Cloud App Engine
In this section, we will learn how to deploy a Spring Boot application in Google Cloud App Engine.
1. A little bit of Background
GCP App Engine
App Engine is a fully managed, serverless platform for developing and hosting web applications at scale. You can choose from several popular languages, libraries, and frameworks to develop your apps, and then let App Engine take care of provisioning servers and scaling your app instances based on demand.
Spring Boot
Spring Boot makes it easy to create stand-alone, production-grade Spring-based Applications that you can "just run".
2. Creating a simple spring boot web application
First, open the Spring initializr https://start.spring.io/
Then, Provide the Group and Artifact name. We have provided Group name com.knf.dev.demo and Artifact spring-boot-gcp-helloworld. Here I selected the Maven project - language Java 11 - Spring Boot 2.7.9 and add Spring web dependency.
Then, import the project on your favourite IDE.
Final Project directory:
In order to make the deployment to App Engine easier, we include Google Cloud App Engine Apache Maven Plugin to our pom.xml.
<plugin>
<groupId>com.google.cloud.tools</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>2.2.0</version>
<configuration>
<version>1</version>
<projectId>GCLOUD_CONFIG</projectId>
</configuration>
</plugin>
Complete pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.7.9</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.knf.dev.demo</groupId>
<artifactId>spring-boot-gcp-helloworld</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>spring-boot-gcp-helloworld</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>11</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>com.google.cloud.tools</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>2.2.0</version>
<configuration>
<version>1</version>
<projectId>GCLOUD_CONFIG</projectId>
</configuration>
</plugin>
</plugins>
</build>
</project>
app.yaml
To deploy the application to App Engine standard environment, you must create an appengine folder in the main directory: src/main/appengine/ and create an app.yaml file inside the appengine folder and add the following content.
runtime: java11
instance_class: F1
Create Hello Controller
package com.knf.dev.demo.controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HelloController {
@GetMapping("/hello")
public String getMessage()
{
return "Hello World!";
}
}
- Spring @RestController annotation is used to create RESTful web services using Spring MVC. Spring RestController takes care of mapping request data to the defined request handler method. Once response body is generated from the handler method, it converts it to JSON response.
- @GetMapping annotation for mapping HTTP GET requests onto specific handler methods.
Application.java
package com.knf.dev.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
3. Create a New Repository and Upload Files on GitHub
First, sign in to Github https://github.com/
Then, create a new repository "spring-boot-gcp-helloworld".
Then, upload the source code from your local machine to the newly created Github repo.
4. Create a GCP Project
We will need to create or select a GCP project that we’ll use to deploy to.
First, Sign into the Google console at https://console.cloud.google.com.
You can create a new project by first selecting the project dropdown in the top left and selecting "New Project".
Next, specify your GCP Project name and Project ID.
5. Deploy the application to App Engine
Start the Google Cloud Shell in the browser.
Button to activate cloud shell is marked in the below image.
Next, clone the git repository:
git clone https://github.com/knowledgefactory4u/spring-boot-gcp-helloworld.git
When creating an application in App Engine, we need to choose a region where the application will be running. The list of regions can be shown by executing the command:
gcloud app regions list
We will choose region us-west4 and create our AppEngine app:
gcloud app create --region us-west4
gcloud app create --region us-west4
Change the directory to spring-boot-gcp-helloworld.
cd spring-boot-gcp-helloworld
From within your git repository directory, you can deploy your application by executing below command.
mvn -DskipTests package appengine:deploy
If everything goes fine, then you will see the following similar output in your cloud shell:
Copy the URL of the deployed service.
6. Verify the API using postman
