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 spring-projectsgh-22358

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/elasticsearch/ElasticSearchRestHealthContributorAutoConfiguration.java

@@ -19,6 +19,7 @@
 import java.util.Map;
 
 import org.elasticsearch.client.RestClient;
+import org.elasticsearch.client.RestHighLevelClient;
 
 import org.springframework.boot.actuate.autoconfigure.health.CompositeHealthContributorConfiguration;
 import org.springframework.boot.actuate.autoconfigure.health.ConditionalOnEnabledHealthIndicator;
@@ -41,16 +42,16 @@
  * @since 2.1.1
  */
 @Configuration(proxyBeanMethods = false)
-@ConditionalOnClass(RestClient.class)
-@ConditionalOnBean(RestClient.class)
+@ConditionalOnClass(RestHighLevelClient.class)
+@ConditionalOnBean(RestHighLevelClient.class)
 @ConditionalOnEnabledHealthIndicator("elasticsearch")
 @AutoConfigureAfter(ElasticsearchRestClientAutoConfiguration.class)
 public class ElasticSearchRestHealthContributorAutoConfiguration
-		extends CompositeHealthContributorConfiguration<ElasticsearchRestHealthIndicator, RestClient> {
+		extends CompositeHealthContributorConfiguration<ElasticsearchRestHealthIndicator, RestHighLevelClient> {
 
 	@Bean
 	@ConditionalOnMissingBean(name = { "elasticsearchHealthIndicator", "elasticsearchHealthContributor" })
-	public HealthContributor elasticsearchHealthContributor(Map<String, RestClient> clients) {
+	public HealthContributor elasticsearchHealthContributor(Map <String, RestHighLevelClient> clients) {
 		return createContributor(clients);
 	}
 

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/elasticsearch/ElasticsearchRestHealthIndicator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,7 @@
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.Response;
 import org.elasticsearch.client.RestClient;
+import org.elasticsearch.client.RestHighLevelClient;
 
 import org.springframework.boot.actuate.health.AbstractHealthIndicator;
 import org.springframework.boot.actuate.health.Health;
@@ -49,6 +50,10 @@ public class ElasticsearchRestHealthIndicator extends AbstractHealthIndicator {
 
 	private final JsonParser jsonParser;
 
+	public ElasticsearchRestHealthIndicator(RestHighLevelClient client) {
+		this(client.getLowLevelClient());
+	}
+
 	public ElasticsearchRestHealthIndicator(RestClient client) {
 		super("Elasticsearch health check failed");
 		this.client = client;

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/elasticsearch/ElasticsearchRestClientAutoConfiguration.java

@@ -16,13 +16,30 @@
 
 package org.springframework.boot.autoconfigure.elasticsearch;
 
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.time.Duration;
+
+import org.apache.http.HttpHost;
+import org.apache.http.auth.AuthScope;
+import org.apache.http.auth.Credentials;
+import org.apache.http.auth.UsernamePasswordCredentials;
+import org.apache.http.client.config.RequestConfig;
+import org.apache.http.impl.client.BasicCredentialsProvider;
+import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
 import org.elasticsearch.client.RestClient;
+import org.elasticsearch.client.RestClientBuilder;
+import org.elasticsearch.client.RestHighLevelClient;
 
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.context.properties.PropertyMapper;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.context.annotation.Import;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for Elasticsearch REST clients.
@@ -32,11 +49,141 @@
  * @since 2.1.0
  */
 @Configuration(proxyBeanMethods = false)
-@ConditionalOnClass(RestClient.class)
+@ConditionalOnClass(RestHighLevelClient.class)
 @EnableConfigurationProperties(ElasticsearchRestClientProperties.class)
-@Import({ ElasticsearchRestClientConfigurations.RestClientBuilderConfiguration.class,
-		ElasticsearchRestClientConfigurations.RestHighLevelClientConfiguration.class,
-		ElasticsearchRestClientConfigurations.RestClientFallbackConfiguration.class })
 public class ElasticsearchRestClientAutoConfiguration {
 
+	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnMissingBean(RestClientBuilder.class)
+	static class RestClientBuilderConfiguration {
+
+		@Bean
+		RestClientBuilderCustomizer defaultRestClientBuilderCustomizer(ElasticsearchRestClientProperties properties) {
+			return new DefaultRestClientBuilderCustomizer(properties);
+		}
+
+		@Bean
+		RestClientBuilder elasticsearchRestClientBuilder(ElasticsearchRestClientProperties properties,
+				ObjectProvider<RestClientBuilderCustomizer> builderCustomizers) {
+			HttpHost[] hosts = properties.getUris().stream().map(this::createHttpHost).toArray(HttpHost[]::new);
+			RestClientBuilder builder = RestClient.builder(hosts);
+			builder.setHttpClientConfigCallback((httpClientBuilder) -> {
+				builderCustomizers.orderedStream().forEach((customizer) -> customizer.customize(httpClientBuilder));
+				return httpClientBuilder;
+			});
+			builder.setRequestConfigCallback((requestConfigBuilder) -> {
+				builderCustomizers.orderedStream().forEach((customizer) -> customizer.customize(requestConfigBuilder));
+				return requestConfigBuilder;
+			});
+			builderCustomizers.orderedStream().forEach((customizer) -> customizer.customize(builder));
+			return builder;
+		}
+
+		private HttpHost createHttpHost(String uri) {
+			try {
+				return createHttpHost(URI.create(uri));
+			}
+			catch (IllegalArgumentException ex) {
+				return HttpHost.create(uri);
+			}
+		}
+
+		private HttpHost createHttpHost(URI uri) {
+			if (!StringUtils.hasLength(uri.getUserInfo())) {
+				return HttpHost.create(uri.toString());
+			}
+			try {
+				return HttpHost.create(new URI(uri.getScheme(), null, uri.getHost(), uri.getPort(), uri.getPath(),
+						uri.getQuery(), uri.getFragment()).toString());
+			}
+			catch (URISyntaxException ex) {
+				throw new IllegalStateException(ex);
+			}
+		}
+
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnMissingBean(RestHighLevelClient.class)
+	static class RestHighLevelClientConfiguration {
+
+		@Bean
+		RestHighLevelClient elasticsearchRestHighLevelClient(RestClientBuilder restClientBuilder) {
+			return new RestHighLevelClient(restClientBuilder);
+		}
+
+	}
+
+	static class DefaultRestClientBuilderCustomizer implements RestClientBuilderCustomizer {
+
+		private static final PropertyMapper map = PropertyMapper.get();
+
+		private final ElasticsearchRestClientProperties properties;
+
+		DefaultRestClientBuilderCustomizer(ElasticsearchRestClientProperties properties) {
+			this.properties = properties;
+		}
+
+		@Override
+		public void customize(RestClientBuilder builder) {
+		}
+
+		@Override
+		public void customize(HttpAsyncClientBuilder builder) {
+			builder.setDefaultCredentialsProvider(new PropertiesCredentialsProvider(this.properties));
+		}
+
+		@Override
+		public void customize(RequestConfig.Builder builder) {
+			map.from(this.properties::getConnectionTimeout).whenNonNull().asInt(Duration::toMillis)
+					.to(builder::setConnectTimeout);
+			map.from(this.properties::getReadTimeout).whenNonNull().asInt(Duration::toMillis)
+					.to(builder::setSocketTimeout);
+		}
+
+	}
+
+	private static class PropertiesCredentialsProvider extends BasicCredentialsProvider {
+
+		PropertiesCredentialsProvider(ElasticsearchRestClientProperties properties) {
+			if (StringUtils.hasText(properties.getUsername())) {
+				Credentials credentials = new UsernamePasswordCredentials(properties.getUsername(),
+						properties.getPassword());
+				setCredentials(AuthScope.ANY, credentials);
+			}
+			properties.getUris().stream().map(this::toUri).filter(this::hasUserInfo)
+					.forEach(this::addUserInfoCredentials);
+		}
+
+		private URI toUri(String uri) {
+			try {
+				return URI.create(uri);
+			}
+			catch (IllegalArgumentException ex) {
+				return null;
+			}
+		}
+
+		private boolean hasUserInfo(URI uri) {
+			return uri != null && StringUtils.hasLength(uri.getUserInfo());
+		}
+
+		private void addUserInfoCredentials(URI uri) {
+			AuthScope authScope = new AuthScope(uri.getHost(), uri.getPort());
+			Credentials credentials = createUserInfoCredentials(uri.getUserInfo());
+			setCredentials(authScope, credentials);
+		}
+
+		private Credentials createUserInfoCredentials(String userInfo) {
+			int delimiter = userInfo.indexOf(":");
+			if (delimiter == -1) {
+				return new UsernamePasswordCredentials(userInfo, null);
+			}
+			String username = userInfo.substring(0, delimiter);
+			String password = userInfo.substring(delimiter + 1);
+			return new UsernamePasswordCredentials(username, password);
+		}
+
+	}
+
 }