= Spring Boot - Actuator

Spring Boot Actuator includes a number of additional features to help you monitor and
manage your application when it's pushed to production. You can choose to manage and
monitor your application using HTTP endpoints, with JMX or even by remote shell (SSH or
Telnet).  Auditing, health and metrics gathering can be automatically applied to your
application. The
https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#production-ready[user guide]
covers the features in more detail.

== Enabling the Actuator
The simplest way to enable the features is to add a dependency to the
`spring-boot-starter-actuator` '`Starter`'. To add the actuator to a Maven based
project, add the following '`Starter`' dependency:

[source,xml,indent=0]
----
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-actuator</artifactId>
		</dependency>
	</dependencies>
----

For Gradle, use the declaration:

[indent=0]
----
	dependencies {
		compile("org.springframework.boot:spring-boot-starter-actuator")
	}
----

== Features
* **Endpoints** Actuator endpoints allow you to monitor and interact with your
  application. Spring Boot includes a number of built-in endpoints and you can also add
  your own. For example the `health` endpoint provides basic application health
  information. Run up a basic application and look at `/health` (and see `/mappings` for
  a list of other HTTP endpoints).
* **Metrics** Spring Boot Actuator includes a metrics service with "`gauge`" and
  "`counter`" support.  A "`gauge`" records a single value; and a "`counter`" records a
  delta (an increment or decrement). Metrics for all HTTP requests are automatically
  recorded, so if you hit the `metrics` endpoint should see a sensible response.
* **Audit** Spring Boot Actuator has a flexible audit framework that will publish events
  to an `AuditEventRepository`. Once Spring Security is in play it automatically publishes
  authentication events by default. This can be very useful for reporting, and also to
  implement a lock-out policy based on authentication failures.
* **Process Monitoring** In Spring Boot Actuator you can find `ApplicationPidFileWriter`
  which creates a file containing the application PID (by default in the application
  directory with a file name of `application.pid`).
