Deploy Your First App: Hello World on Cloud Run & App Engine

Ready to deploy your first Java app on Google Cloud Platform? In this tutorial, we’ll guide you through deploying a basic “Hello World” web app using two powerful GCP services: Cloud Run and App Engine. Both options are serverless and ideal for beginners.

1. Prerequisites

• A GCP project with billing enabled
• gcloud CLI installed and initialized
• Docker installed (for Cloud Run)
• Java 17+ and Maven or Gradle installed
• A simple Spring Boot app

2. Hello World with Cloud Run

Step 1: Create Your Spring Boot App

// MainApplication.java
package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.*;

@SpringBootApplication
@RestController
public class MainApplication {

    public static void main(String[] args) {
        SpringApplication.run(MainApplication.class, args);
    }

    @GetMapping("/")
    public String hello() {
        return "Hello from Cloud Run!";
    }
}

<!-- pom.xml -->
<project xmlns="http://maven.apache.org/POM/4.0.0" ...>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.example</groupId>
  <artifactId>demo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <properties>
    <java.version>17</java.version>
    <spring.boot.version>3.2.0</spring.boot.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

Step 2: Create a Dockerfile

# Dockerfile
FROM eclipse-temurin:17-jdk-alpine
WORKDIR /app
COPY target/demo-0.0.1-SNAPSHOT.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]

Step 3: Build and Deploy

mvn clean package

gcloud builds submit --tag gcr.io/YOUR_PROJECT_ID/hello-app

gcloud run deploy hello-app \
  --image gcr.io/YOUR_PROJECT_ID/hello-app \
  --platform managed \
  --region us-central1 \
  --allow-unauthenticated

Once deployed, Cloud Run will return a public HTTPS URL where your app is live!

3. Hello World with App Engine

Step 1: Use the Same App

You can reuse the same Spring Boot app and built JAR. Add an App Engine config:

# app.yaml
runtime: java17
entrypoint: java -jar demo-0.0.1-SNAPSHOT.jar

handlers:
- url: /.*
  script: auto

Step 2: Deploy to App Engine

gcloud app create --region=us-central
gcloud app deploy

After deployment, your app will be live at:

https://PROJECT_ID.REGION_ID.r.appspot.com

4. Summary

Both Cloud Run and App Engine make deploying Java apps simple and fast.

Feature	Cloud Run	App Engine
Uses Containers	Yes	Optional (uses JARs)
Flexibility	High (custom Docker)	Moderate (managed JRE)
Best for	Microservices & custom stack	Simple Java web apps

Next Steps

• Add configuration via environment variables
• Connect a custom domain
• Add authentication with Firebase or IAM
• Automate deployments using Cloud Build or GitHub Actions

Now that your app is live, try modifying the message, adding new routes, or connecting it to a database like Firestore or Cloud SQL. The cloud is your playground!