Logging and Monitoring in Spring Boot [Java Spring Boot Mastery Series – Part 11]

Monitoring and logging are vital for observing the health and behavior of your Spring Boot application.

📝 1. Logging with Spring Boot (SLF4J + Logback)

Spring Boot uses SLF4J with Logback by default.

Example:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@RestController
public class LoggingController {

    private static final Logger logger = LoggerFactory.getLogger(LoggingController.class);

    @GetMapping("/log")
    public String logExample() {
        logger.info("INFO log");
        logger.warn("WARN log");
        logger.error("ERROR log");
        return "Logs printed to console";
    }
}

📌 Explanation:

• LoggerFactory.getLogger initializes logger for the class.
• logger.info/warn/error generates logs at various levels

⚙️ 2. Customize Logging Level in application.properties

logging.level.org.springframework=INFO
logging.level.com.yourapp=DEBUG
logging.file.name=app.log

Explanation:

• Adjust log levels per package.
• Output to a file app.log.

🔍 3. Actuator for Monitoring

Spring Boot Actuator provides endpoints for metrics and monitoring.

Add Dependency:

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

Enable Endpoints in application.properties

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

Access Endpoints:

http://localhost:8080/actuator/health
http://localhost:8080/actuator/metrics

Use Case:

Helpful for Prometheus, Grafana integration.

📦 4. Micrometer Integration

Micrometer provides metrics facade with built-in support for Prometheus, New Relic, etc.

Example with Prometheus:

<dependency>
    <groupId>io.micrometer</groupId>
    <artifactId>micrometer-registry-prometheus</artifactId>
</dependency>

application.properties

management.metrics.export.prometheus.enabled=true
management.endpoints.web.exposure.include=prometheus

📘 What are Prometheus and New Relic?

📊 Prometheus

Prometheus is an open-source systems monitoring and alerting toolkit originally developed by SoundCloud. It is especially well-suited for time-series data (e.g., system metrics like CPU usage over time).

🔧 Key Features:

• Pull-based data collection over HTTP.
• Stores data in a time-series format.
• Powerful query language called PromQL.
• Integrates with Grafana for visualization.

✅ Use Case in Spring Boot:

Used in combination with Micrometer to collect custom application metrics (e.g., number of HTTP requests, execution time of methods).

🧠 New Relic

New Relic is a commercial full-stack observability platform. It provides real-time performance monitoring for applications, infrastructure, and user experience.

🔧 Key Features:

• Auto-instrumentation of JVM-based applications.
• Deep tracing, dashboards, and alerting.
• Supports custom metrics and distributed tracing.

✅ Use Case in Spring Boot:

By adding the New Relic agent to your JVM, you can automatically monitor your app’s memory, database queries, external calls, and more.

➡️ Next Up: Part 12 – Testing in Spring Boot (Unit + Integration)