Spring Boot Starter Actuator

Introduction

Spring Boot Starter Actuator is a module within the Spring Boot ecosystem that provides essential production-ready features for monitoring and managing a Spring Boot application. This includes functionality to inspect the health, metrics, and other vital statistics of your application. Actuator exposes various built-in endpoints through which developers can track the application’s status and behavior, even in its running state. In this guide, we will explore what Spring Boot Starter Actuator is, how it works, and demonstrate its use with Kotlin examples.

Solution

Adding Spring Boot Starter Actuator to Your Project

To begin using Actuator, you need to add the spring-boot-starter-actuator dependency to your project’s build.gradle (Kotlin DSL) file:

dependencies {
    implementation("org.springframework.boot:spring-boot-starter-actuator")
}

Advantages

• Ease of Integration: Simply adding the dependency integrates actuator endpoints.
• Minimal Configuration: Works out-of-the-box with minimal setup.
  

  Disadvantages

• Security: Some endpoints expose sensitive information; securing these endpoints is crucial.

Exposing Actuator Endpoints

By default, not all endpoints are exposed. To expose endpoints, configure them in your application.properties or application.yml file.

# application.properties
management.endpoints.web.exposure.include=*

Advantages

• Customizable: Ability to expose only necessary endpoints.
• Security: Minimizes risk by not exposing sensitive endpoints by default.
  

  Disadvantages

• Risk of exposing too much: Including all (*) can lead to exposing sensitive data.

Health Check Endpoint

Actuator provides a /actuator/health endpoint. This checks the application’s health.
Here is an example of checking the health status.

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

@Component
class MyHealthIndicator : HealthIndicator {
    override fun health(): Health {
        val errorCode = check() // performs a specific health check
        return if (errorCode == 0) {
            Health.up().build()
        } else {
            Health.down().withDetail("Error Code", errorCode).build()
        }
    }

    fun check(): Int {
        // perform some specific health check
        return 0
    }
}

Output:

{
  "status": "UP"
}

Advantages

• Custom Health Checks: Easily integrate custom health checks.
  

  Disadvantages

• Maintenance: Custom health indicators add maintenance overhead.

Metrics Endpoint

The /actuator/metrics endpoint gives insights into various metrics such as memory usage, system uptime, etc.

import io.micrometer.core.instrument.MeterRegistry
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.boot.CommandLineRunner
import org.springframework.stereotype.Component

@Component
class MetricsRunner(@Autowired private val meterRegistry: MeterRegistry): CommandLineRunner {

    override fun run(vararg args: String?) {
        meterRegistry.counter("my.counter", "type", "http").increment()
    }
}

Output:

{
  "name": "my.counter",
  "count": 1
}

Advantages

• Detailed Metrics: Provides a variety of application metrics out of the box.
  

  Disadvantages

• Complexity: Understanding and leveraging all available metrics can be complex.

Custom Endpoints

Custom endpoints allow defining your metrics or indicators.

import org.springframework.boot.actuate.endpoint.annotation.Endpoint
import org.springframework.boot.actuate.endpoint.annotation.ReadOperation
import org.springframework.stereotype.Component

@Component
@Endpoint(id = "customEndpoint")
class CustomEndpoint {

    @ReadOperation
    fun customEndpoint(): Map<String, String> {
        return mapOf("key" to "value")
    }
}

Configure the endpoint in your application.properties file.

management.endpoints.web.exposure.include=*

Accessing the endpoint:

GET /actuator/customEndpoint

Output:

{
  "key": "value"
}

Advantages

• Flexibility: Create metrics and info tailored to your needs.
  

  Disadvantages

• Learning Curve: Must learn annotations and API for creating endpoints.

Similar Topics

• How does Spring Boot handle security for Actuator endpoints?
• What are the common health indicators in Spring Boot Actuator?
• How can I customize Actuator metrics in a Spring Boot application?
• How to create a custom endpoint with Spring Boot Actuator?
• How to monitor application health using Spring Boot Actuator?
• How to secure Spring Boot Actuator endpoints?
• What are the essential production metrics provided by Spring Boot Actuator?
• How to configure and use Micrometer with Spring Boot Actuator?
• How to use Spring Boot Actuator for monitoring and managing application performance?
• How can I expose only specific endpoints in Spring Boot Actuator?
• How to integrate Spring Boot Actuator with Prometheus?
• How to use Spring Boot Actuator with a custom management port?
• How to disable specific Actuator endpoints in Spring Boot?