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In this tutorial, we’ll set up and run two cooperating microservices on your local machine:
  1. Spring Boot “numeric” service
  2. Node.js “plus-one” service (packaged in Docker)
By the end, you’ll be able to call endpoints on the Spring Boot app that delegate to the Node.js service and observe the logs in both environments.

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1. Clone and Import the Project

  1. Clone the Git repository and open it in your IDE of choice (Spring Tool Suite, IntelliJ, VSCode, etc.).
The image shows a Windows File Explorer window open to a directory named "devsecops-k8s-demo," containing various folders and files. The desktop taskbar is visible at the bottom, displaying several application icons.
  1. Import the project as a Maven project:
The image shows the Spring Tool Suite IDE with an "Import Maven Projects" dialog open, displaying options to select Maven projects from a specified directory. The desktop taskbar is visible at the bottom with various application icons.

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2. Inspect the Maven POM

Open the pom.xml file at the project root. You’ll find the Spring Boot parent and starter dependencies: 
<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
           http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>numeric</groupId>
  <artifactId>numeric</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>numeric</name>
  <description>Demo for DevSecOps</description>

  <properties>
    <java.version>1.8</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>
</project>
For more details on Maven POM configuration, refer to the Maven Reference Documentation.

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3. Review the Spring Boot Controller

The core logic resides in NumericController.java. It defines three endpoints: 
package com.devsecops;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;

@RestController
public class NumericController {
    private final Logger logger = LoggerFactory.getLogger(getClass());

    // For Kubernetes use:
    private static final String baseURL = "http://node-service:5000/plusone";
    // For local testing, uncomment the line below and comment out the Kubernetes URL:
    // private static final String baseURL = "http://localhost:5000/plusone";

    private final RestTemplate restTemplate = new RestTemplate();

    @GetMapping("/")
    public String welcome() {
        return "Kubernetes DevSecOps";
    }

    @GetMapping("/compare/{value}")
    public String compareToFifty(@PathVariable int value) {
        return (value > 50) ? "Greater than 50" : "Smaller than or equal to 50";
    }

    @GetMapping("/increment/{value}")
    public ResponseEntity<String> increment(@PathVariable int value) {
        logger.info("Value received in request: " + value);
        ResponseEntity<String> response =
            restTemplate.getForEntity(baseURL + "/" + value, String.class);
        String nodeResponse = response.getBody();
        String body = "Spring received: " + value + "\nNode response: " + nodeResponse;
        return ResponseEntity.ok(body);
    }
}
Toggle the baseURL between localhost (for local debugging) and node-service (for Kubernetes) before running the app.

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4. Run the Node.js “plus-one” Service in Docker

Ensure Docker is installed and running on your machine.
Make sure port 5000 is free. If another service is using this port, stop it or choose a different host port.
Execute: 
docker run -p 5000:5000 siddharth67/node-service:v1
You should see output similar to: 
> node app.js
HOSTNAME is 6dceae5489

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4.1 Test the Node.js Service

In a browser or via curl: 
curl http://localhost:5000/plusone/999
Expected response: 1000
The image shows a web browser displaying a page with the number "1000" on it. The URL in the address bar is "localhost:5000/plusone/999".

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5. Run and Test the Spring Boot Application

Start the Spring Boot service:
  • In your IDE: Run As → Spring Boot App
  • Or via Maven: 
    mvn spring-boot:run
By default, it listens on port 8080. Test the endpoints:
EndpointMethodDescriptionExample Command
/GETWelcome messagecurl http://localhost:8080/
/compare/{value}GETCompare number to 50curl http://localhost:8080/compare/55
/increment/{value}GETIncrement via Node.js service and respondcurl http://localhost:8080/increment/55
Sample Responses
  1. Welcome: 
    $ curl http://localhost:8080/
Kubernetes DevSecOps
  2. Compare: 
    $ curl http://localhost:8080/compare/55
Greater than 50
  3. Increment: 
    $ curl http://localhost:8080/increment/55
Spring received: 55
Node response: 56
The image shows a web browser displaying a local URL with the number "56" on a blank page. The browser has multiple tabs open, and there is a small video call or webcam feed in the top right corner.
In your IDE console, look for: 
... INFO ... NumericController     : Value received in request: 55
In the Docker container logs you’ll see: 
Value Received = 55

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6. Next Steps

Before deploying to Kubernetes:
  1. Switch baseURL back to 
    private static final String baseURL = "http://node-service:5000/plusone";
  2. Configure a Maven build and set up a Jenkins pipeline to automate the Spring Boot deployment.

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