Why monitoring matters in Spring Boot - See It in Action

Why monitoring matters

📖 Scenario: You are running a small Spring Boot web application that serves users. To keep your app healthy and responsive, you want to monitor its status and key metrics like uptime and request count.

🎯 Goal: Build a simple Spring Boot app with a health check endpoint and a counter for requests. Then add monitoring logic to track and display these metrics.

📋 What You'll Learn

Create a Spring Boot application class

Add a REST controller with a health check endpoint

Add a request counter variable

Increment the counter on each request

Print the current health status and request count

💡 Why This Matters

🌍 Real World

Monitoring helps keep applications running smoothly by alerting you to problems early. This simple app shows how to track basic health and usage.

💼 Career

DevOps engineers and backend developers often build and maintain monitoring endpoints to ensure system reliability and performance.

1

Create Spring Boot application class

Create a Spring Boot application class called MonitoringApp with the @SpringBootApplication annotation and a main method that runs the app using SpringApplication.run(MonitoringApp.class, args).

Spring Boot

// Your code here

Need a hint?

Use @SpringBootApplication on the class and write a main method that calls SpringApplication.run.

2

Add REST controller with health check

Add a REST controller class called HealthController with the @RestController annotation. Inside it, create a method healthCheck mapped to /health using @GetMapping that returns the string "UP".

Spring Boot

import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.GetMapping;

// Your code here

Need a hint?

Use @RestController on the class and @GetMapping("/health") on the method that returns "UP".

3

Add request counter and increment logic

Inside the HealthController class, add a private integer variable called requestCount initialized to 0. Modify the healthCheck method to increment requestCount by 1 each time it is called.

Spring Boot

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

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

@RestController
class HealthController {
    private int requestCount = 0;

    @GetMapping("/health")
    public String healthCheck() {
        // Your code here
    }
}

Need a hint?

Declare private int requestCount = 0; and add requestCount++; inside the healthCheck method.

4

Print health status and request count

Modify the healthCheck method to return a string showing both the health status and the current requestCount in this format: "Status: UP, Requests: X" where X is the value of requestCount. Use String.format to build the string.

Spring Boot

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

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

@RestController
class HealthController {
    private int requestCount = 0;

    @GetMapping("/health")
    public String healthCheck() {
        requestCount++;
        // Your code here
    }
}

Need a hint?

Use return String.format("Status: UP, Requests: %d", requestCount); to show the status and count.