Spring Boot 4 Microservices & REST APIs · Aula

Verificações de integridade e métricas

Implemente o Spring Boot Actuator para expor endpoints de integridade e coletar métricas da aplicação.

Verificações de integridade e métricas é uma aula grátis de Spring Boot 4 Microservices & REST APIs no CoddyKit. Esta é a aula 2 de 3. Você pode ler a aula completa abaixo gratuitamente — depois pratica ao vivo no navegador com um editor de código integrado e um tutor de IA 24/7. Faz parte do caminho de aprendizado de Spring Boot 4 Microservices & REST APIs, e seu progresso é sincronizado entre a web e o app CoddyKit. O curso de Spring Boot 4 Microservices & REST APIs inclui 3 aulas no total.

Partes desta aula ainda não foram traduzidas e aparecem em inglês.

What is Spring Boot Actuator?

When running microservices, monitoring their health and performance is super important. Spring Boot Actuator provides a set of production-ready features to help you do just that!

It exposes operational information about your running application, making it easier to observe and manage.

Add Actuator Dependency

To start using Actuator, you just need to add its dependency to your Spring Boot project. This is typically done in your pom.xml for Maven or build.gradle for Gradle.

Here's how to add it with Maven:

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

Explore Default Endpoints

Once the Actuator dependency is added, Spring Boot automatically configures several useful endpoints. These endpoints provide valuable insights into your application's state.

/actuator/health: Shows the application's health status.
/actuator/info: Displays general application information.
/actuator/metrics: Provides detailed metrics data.

Checking Application Health

The /actuator/health endpoint is a fundamental part of monitoring. It tells you if your application and its integrated components (like databases or disk space) are functioning correctly.

A simple "UP" status means everything is good! Run this basic app and check its health endpoint.

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

Accessing Health Endpoint

After running the previous application, open your browser and navigate to http://localhost:8080/actuator/health.

You should see a JSON response indicating the application's overall status, typically {"status":"UP"}.

This is a quick way to verify if your service is alive!

Create Custom Health Checks

You can extend Actuator's health checks to include your own custom logic. For example, checking the status of an external API, a message queue, or a specific business process.

To do this, you implement the HealthIndicator interface:

import org.springframework.boot.actuate.health.Health;
import org.springframework.boot.actuate.health.HealthIndicator;
import org.springframework.stereotype.Component;

@Component
public class CustomServiceHealthIndicator implements HealthIndicator {
  private final String SERVICE_NAME = "MyExternalService";

  @Override
  public Health health() {
    if (isServiceUp()) {
      return Health.up().withDetail(SERVICE_NAME, "Available").build();
    }
    return Health.down().withDetail(SERVICE_NAME, "Not Available").build();
  }

  private boolean isServiceUp() {
    // Simulate checking an external service
    return Math.random() > 0.3; // 70% chance of being up
  }
}

Understanding Application Metrics

Metrics are numerical data points that describe your application's behavior over time. They are crucial for understanding performance, resource usage, and identifying potential bottlenecks.

Spring Boot Actuator, powered by Micrometer, automatically collects various metrics:

CPU and memory usage
HTTP request counts and latencies
Database connection pool statistics

Querying Metrics Data

The /actuator/metrics endpoint provides a list of all available metrics. You can then query specific metrics for detailed information.

Visit http://localhost:8080/actuator/metrics to see available metrics.
Then, try http://localhost:8080/actuator/metrics/jvm.memory.used to see the specific memory usage metric.

This allows you to gather precise data for monitoring dashboards.

Implement Custom Metrics

Beyond the default metrics, you can track application-specific events using custom metrics. Micrometer provides simple APIs for different metric types like Counters, Gauges, and Timers.

Here's an example of a custom Counter:

import io.micrometer.core.instrument.Counter;
import io.micrometer.core.instrument.MeterRegistry;
import org.springframework.stereotype.Service;

@Service
public class MyService {
  private final Counter customCounter;

  public MyService(MeterRegistry meterRegistry) {
    this.customCounter = Counter.builder("my_app.processed.items")
                                .description("Number of items processed by MyService")
                                .register(meterRegistry);
  }

  public void processItem() {
    System.out.println("Processing an item...");
    customCounter.increment(); // Increment the counter
  }
}

Customize Endpoint Exposure

By default, only /health and /info are typically exposed over HTTP. You can configure which other endpoints Actuator makes available using application.properties or application.yml.

To expose more endpoints like metrics, beans, and env, add this line:

management.endpoints.web.exposure.include=health,info,metrics,beans,env

Actuator Knowledge Check

Let's quickly check your understanding of Spring Boot Actuator's benefits.

Lesson Recap

Great job! In this lesson, you learned about:

Spring Boot Actuator for monitoring and managing microservices.
Implementing health checks using the /actuator/health endpoint.
Creating custom health indicators for specific services.
Understanding and collecting application metrics via /actuator/metrics.
Implementing custom metrics with Micrometer.
The importance of securing Actuator endpoints in production.

Next, we'll dive into centralized logging and dashboarding!

Perguntas Frequentes

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Implemente o Spring Boot Actuator para expor endpoints de integridade e coletar métricas da aplicação. Você pratica Spring Boot 4 Microservices & REST APIs com código prático que executa diretamente no navegador, e um tutor de IA 24/7 responde suas dúvidas enquanto trabalha na aula.

Preciso ter experiência prévia para começar Spring Boot 4 Microservices & REST APIs?

Nenhuma experiência prévia é necessária. Spring Boot 4 Microservices & REST APIs no CoddyKit é estruturado para alunos iniciantes até avançados, então você pode começar aqui ou desde o início e aprender no seu ritmo. Esta é a aula 2 de 3.

Quanto tempo leva a aula “Verificações de integridade e métricas”?

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