Brian Clozel 1d73d4eda7 Remove Elasticsearch RestClient auto-configuration
Prior to this commit, Spring Boot would auto-configure both
Elasticsearch variants: `RestClient` ("Low Level" client) and
`RestHighLevelClient` ("High Level" client).
Since one can be derived from the other, this would create complex and
unclear situations depending on what developers provided with their
configuration.

`RestHighLevelClient` is mostly for actual use of the Elasticsearch API,
with support for specific methods and (de)serialization. On the other
hand, `RestClient` is merely wrapping the Apache HTTP client for
load-balancing support and low level HTTP features.

This commit completely removes the support for `RestClient` in Spring
Boot and now requires the presence of the
`org.elasticsearch.client:elasticsearch-rest-high-level-client`
dependency for REST client support with Elasticsearch.

Closes gh-22358
2020-09-08 10:17:27 +02:00
..
2020-07-20 13:58:19 +01:00

= 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 or JMX endpoints. 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 recommended 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 following declaration:

[indent=0]
----
	dependencies {
		implementation '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 `/actuator/health`.
* **Metrics** Spring Boot Actuator provides dimensional metrics by integrating with
  https://micrometer.io[Micrometer].
* **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.