Add support for customizing the auto-configured ClientResources

Closes gh-26792

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/redis/ClientResourcesBuilderCustomizer.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012-2021 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.data.redis;
+
+import io.lettuce.core.resource.ClientResources;
+
+/**
+ * Callback interface that can be implemented by beans wishing to customize the
+ * {@link ClientResources} via a {@link ClientResources.Builder} whilst retaining default
+ * auto-configuration.
+ *
+ * @author Stephane Nicoll
+ * @since 2.6.0
+ */
+public interface ClientResourcesBuilderCustomizer {
+
+	/**
+	 * Customize the {@link ClientResources.Builder}.
+	 * @param clientResourcesBuilder the builder to customize
+	 */
+	void customize(ClientResources.Builder clientResourcesBuilder);
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/redis/LettuceConnectionConfiguration.java

@@ -65,8 +65,10 @@ class LettuceConnectionConfiguration extends RedisConnectionConfiguration {
 
 	@Bean(destroyMethod = "shutdown")
 	@ConditionalOnMissingBean(ClientResources.class)
-	DefaultClientResources lettuceClientResources() {
-		return DefaultClientResources.create();
+	DefaultClientResources lettuceClientResources(ObjectProvider<ClientResourcesBuilderCustomizer> customizers) {
+		DefaultClientResources.Builder builder = DefaultClientResources.builder();
+		customizers.orderedStream().forEach((customizer) -> customizer.customize(builder));
+		return builder.build();
 	}
 
 	@Bean

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/redis/RedisAutoConfigurationTests.java

@@ -27,6 +27,8 @@ import io.lettuce.core.ClientOptions;
 import io.lettuce.core.cluster.ClusterClientOptions;
 import io.lettuce.core.cluster.ClusterTopologyRefreshOptions;
 import io.lettuce.core.cluster.ClusterTopologyRefreshOptions.RefreshTrigger;
+import io.lettuce.core.resource.DefaultClientResources;
+import io.lettuce.core.tracing.Tracing;
 import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
 import org.junit.jupiter.api.Test;
 
@@ -53,6 +55,7 @@ import org.springframework.util.StringUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link RedisAutoConfiguration}.
@@ -97,6 +100,16 @@ class RedisAutoConfigurationTests {
 				});
 	}
 
+	@Test
+	void testCustomizeClientResources() {
+		Tracing tracing = mock(Tracing.class);
+		this.contextRunner.withBean(ClientResourcesBuilderCustomizer.class, () -> (builder) -> builder.tracing(tracing))
+				.run((context) -> {
+					DefaultClientResources clientResources = context.getBean(DefaultClientResources.class);
+					assertThat(clientResources.tracing()).isEqualTo(tracing);
+				});
+	}
+
 	@Test
 	void testCustomizeRedisConfiguration() {
 		this.contextRunner.withUserConfiguration(CustomConfiguration.class).run((context) -> {

spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/nosql.adoc

@@ -42,6 +42,7 @@ include::{docs-java}/features/nosql/redis/connecting/MyBean.java[]
 ----
 
 TIP: You can also register an arbitrary number of beans that implement `LettuceClientConfigurationBuilderCustomizer` for more advanced customizations.
+`ClientResources` can also be customized using `ClientResourcesBuilderCustomizer`.
 If you use Jedis, `JedisClientConfigurationBuilderCustomizer` is also available.
 
 If you add your own `@Bean` of any of the auto-configured types, it replaces the default (except in the case of `RedisTemplate`, when the exclusion is based on the bean name, `redisTemplate`, not its type).