Deprecate Elasticsearch transport and Jest clients

As of Spring Data Moore, the Elasticsearch high level REST client is
supported for Spring Data repositories. The transport client is now
deprecated and is likely to be removed in a future Spring Data release.

This commit deprecates the transport client and marks all the associated
configuration properties as deprecated. The Spring Boot starter depends
on the `spring-data-elasticsearch` project, which now depends on both
transport client and high level REST client.

This commit also deprecates the Jest client, as Spring Boot will focus
on supporting the high level REST client and the reactive client
provided by Spring Data - both being in sync with the fast release pace
of Elasticsearch.

Closes gh-15008

Author: bclozel

Diff for: spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/elasticsearch/ElasticsearchAutoConfiguration.java

@@ -37,12 +37,14 @@
  * @author Mohsin Husen
  * @author Andy Wilkinson
  * @since 1.1.0
+ * @deprecated since 2.2.0 in favor of other auto-configured Elasticsearch clients
  */
 @Configuration(proxyBeanMethods = false)
 @ConditionalOnClass({ Client.class, TransportClientFactoryBean.class })
 @ConditionalOnProperty(prefix = "spring.data.elasticsearch", name = "cluster-nodes",
 		matchIfMissing = false)
 @EnableConfigurationProperties(ElasticsearchProperties.class)
+@Deprecated
 public class ElasticsearchAutoConfiguration {
 
 	private final ElasticsearchProperties properties;

Diff for: spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/elasticsearch/jest/JestAutoConfiguration.java

@@ -42,11 +42,13 @@
  *
  * @author Stephane Nicoll
  * @since 1.4.0
+ * @deprecated since 2.2.0 in favor of other auto-configured Elasticsearch clients
  */
 @Configuration(proxyBeanMethods = false)
 @ConditionalOnClass(JestClient.class)
 @EnableConfigurationProperties(JestProperties.class)
 @AutoConfigureAfter(GsonAutoConfiguration.class)
+@Deprecated
 public class JestAutoConfiguration {
 
 	@Bean(destroyMethod = "shutdownClient")

Diff for: spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -305,6 +305,30 @@
         "level": "error"
       }
     },
+    {
+      "name": "spring.data.elasticsearch.cluster-name",
+      "type": "java.lang.String",
+      "description": "Elasticsearch cluster name.",
+      "deprecation": {
+        "reason": "The transport client support is deprecated. Use other supported clients instead."
+      }
+    },
+    {
+      "name": "spring.data.elasticsearch.cluster-nodes",
+      "type": "java.lang.String",
+      "description": "Comma-separated list of cluster node addresses.",
+      "deprecation": {
+        "reason": "The transport client support is deprecated. Use other supported clients instead."
+      }
+    },
+    {
+      "name": "spring.data.elasticsearch.properties",
+      "type": "java.util.Map<java.lang.String,java.lang.String>",
+      "description": "Additional properties used to configure the client.",
+      "deprecation": {
+        "reason": "The transport client support is deprecated. Use other supported clients instead."
+      }
+    },
     {
       "name": "spring.data.elasticsearch.repositories.enabled",
       "type": "java.lang.Boolean",
@@ -389,7 +413,10 @@
       "name": "spring.elasticsearch.jest.uris",
       "defaultValue": [
         "http://localhost:9200"
-      ]
+      ],
+      "deprecation": {
+        "reason": "The Jest client support is deprecated. Use other supported clients instead."
+      }
     },
     {
       "name": "spring.elasticsearch.rest.uris",

Diff for: spring-boot-project/spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -4782,17 +4782,18 @@ https://www.elastic.co/products/elasticsearch[Elasticsearch] is an open source,
 distributed, RESTful search and analytics engine. Spring Boot offers basic
 auto-configuration for Elasticsearch.
 
-Spring Boot supports several HTTP clients:
+Spring Boot supports several clients:
 
 * The official Java "Low Level" and "High Level" REST clients
 * https://github.com/searchbox-io/Jest[Jest]
 
-The transport client is still being used by
-https://github.com/spring-projects/spring-data-elasticsearch[Spring Data Elasticsearch],
-which you can start using with the `spring-boot-starter-data-elasticsearch` "`Starter`".
+The transport client is still available but its support has been deprecated in
+https://github.com/spring-projects/spring-data-elasticsearch[Spring Data Elasticsearch]
+and will be removed in a future release. Spring Boot provides a dedicated "`Starter`",
+`spring-boot-starter-data-elasticsearch`.
 
 [[boot-features-connecting-to-elasticsearch-rest]]
-==== Connecting to Elasticsearch by REST clients
+==== Connecting to Elasticsearch using REST clients
 Elasticsearch ships
 https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/index.html[two different REST clients]
 that you can use to query a cluster: the "Low Level" client and the "High Level" client.
@@ -4819,7 +4820,10 @@ any existing `RestClient` bean, reusing its HTTP configuration.
 
 
 [[boot-features-connecting-to-elasticsearch-jest]]
-==== Connecting to Elasticsearch by Using Jest
+==== Connecting to Elasticsearch using Jest
+Now that Spring Boot supports the official `RestHighLevelClient`, Jest support is
+deprecated.
+
 If you have `Jest` on the classpath, you can inject an auto-configured `JestClient` that
 by default targets `http://localhost:9200`. You can further tune how the client is
 configured, as shown in the following example: