In modern production systems, observability is not just an option—it’s a necessity. Whether you're debugging performance issues or trying to monitor application health in real-time, Spring Boot Actuator and Micrometer are your go-to tools in the Spring Boot ecosystem.

Let’s break down what each of them does, how they work together, and why you should be using them.

🔧 What is Spring Boot Actuator?

Spring Boot Actuator brings production-ready features to your Spring Boot application. It provides a rich set of endpoints to help you monitor and manage your application via HTTP, JMX, or custom protocols.

✅ Key Features of Spring Boot Actuator

Endpoint Description
/actuator/health Displays application health info (integrates with DB, disk space, etc.)
/actuator/info Displays custom application info (from application.properties)
/actuator/metrics Shows application metrics collected by Micrometer
/actuator/env Displays all environment properties (use with caution!)
/actuator/beans Lists all Spring beans in the application context
/actuator/mappings Shows all @RequestMapping URLs
/actuator/configprops Lists all @ConfigurationProperties beans
/actuator/loggers View and change log levels at runtime
/actuator/threaddump Provides a JVM thread dump
/actuator/httptrace Displays trace of recent HTTP requests
/actuator/scheduledtasks Lists scheduled tasks in your app
/actuator/auditevents Shows audit events (if enabled)
/actuator/caches Shows details about caches
/actuator/heapdump Allows downloading a heap dump (if JVM supports it)

You can customize which endpoints are exposed using:

management:
  endpoints:
    web:
      exposure:
        include: health, info, metrics, httptrace

📊 What is Micrometer?

Micrometer is a metrics instrumentation facade that allows you to collect and export metrics from your Spring Boot application to popular monitoring systems like Prometheus, Datadog, New Relic, and more.

Micrometer is not an endpoint provider. Instead, it collects metrics and passes them to Spring Boot Actuator, which exposes them via /actuator/metrics.

✅ Out-of-the-box Metrics by Micrometer

Metric Name Description
jvm.memory.used Current memory usage of the JVM
jvm.gc.pause Time taken by garbage collection
jvm.threads.live Number of live threads
jvm.classes.loaded Number of classes loaded into memory
system.cpu.usage System-wide CPU usage
process.cpu.usage CPU usage by your app process
http.server.requests Count, duration, and status of HTTP requests
logback.events Number of logs (info, warn, error)
tomcat.sessions.active.current Number of active sessions
executor.active Active threads in executors
datasource.connections.active Active DB connections
cache.gets, cache.puts Cache access patterns

🚀 Custom Metrics with Micrometer

You can register your own custom metrics using the MeterRegistry bean.

@Autowired
private MeterRegistry meterRegistry;

@PostConstruct
public void initMetrics() {
    meterRegistry.counter("custom.api.calls", "endpoint", "create-user").increment();
}

🧠 Actuator + Micrometer = Full Observability

When you combine both, you get:

  • Real-time application health monitoring
  • JVM, system, and process metrics
  • Fine-grained metrics for HTTP requests, logs, GC, caches, and more
  • Custom metrics integration
  • Export support for Prometheus, Datadog, Graphite, New Relic, etc.

📦 Add to Your Project

In pom.xml (for Maven):

org.springframework.boot
    spring-boot-starter-actuator



    io.micrometer
    micrometer-registry-prometheus

✅ Conclusion

Tool Purpose
Spring Boot Actuator Exposes endpoints to monitor and manage the app
Micrometer Collects metrics and integrates with monitoring systems

Together, these tools bring production-grade observability to your Spring Boot applications with minimal setup. Whether you're debugging an issue, scaling your app, or just keeping an eye on performance, Actuator + Micrometer is a powerhouse duo.

💬 Have you used these tools in production? Share your experience in the comments below!