Add LoadBalancerRestClientBuilderBeanPostProcessor.

spring-cloud-commons/src/main/java/org/springframework/cloud/client/loadbalancer/LoadBalancerAutoConfiguration.java

@@ -32,11 +32,13 @@
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.cloud.client.ServiceInstance;
 import org.springframework.cloud.client.loadbalancer.reactive.ReactiveLoadBalancer;
+import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.client.ClientHttpRequestInterceptor;
 import org.springframework.retry.support.RetryTemplate;
+import org.springframework.web.client.RestClient;
 import org.springframework.web.client.RestTemplate;
 
 /**
@@ -49,7 +51,7 @@
  * @author Olga Maciaszek-Sharma
  */
 @Configuration(proxyBeanMethods = false)
-@ConditionalOnClass(RestTemplate.class)
+@ConditionalOnClass({ RestTemplate.class, RestClient.class })
 @ConditionalOnBean(LoadBalancerClient.class)
 @EnableConfigurationProperties(LoadBalancerClientsProperties.class)
 public class LoadBalancerAutoConfiguration {
@@ -99,6 +101,13 @@ public RestTemplateCustomizer restTemplateCustomizer(final LoadBalancerIntercept
 			};
 		}
 
+		@Bean
+		@ConditionalOnMissingBean
+		LoadBalancerRestClientBuilderBeanPostProcessor lbRestClientPostProcessor(
+				final LoadBalancerInterceptor loadBalancerInterceptor, ApplicationContext context) {
+			return new LoadBalancerRestClientBuilderBeanPostProcessor(loadBalancerInterceptor, context);
+		}
+
 	}
 
 	private static class RetryMissingOrDisabledCondition extends AnyNestedCondition {
@@ -164,6 +173,13 @@ public RestTemplateCustomizer restTemplateCustomizer(
 			};
 		}
 
+		@Bean
+		@ConditionalOnMissingBean
+		LoadBalancerRestClientBuilderBeanPostProcessor lbRestClientPostProcessor(
+				final RetryLoadBalancerInterceptor loadBalancerInterceptor, ApplicationContext context) {
+			return new LoadBalancerRestClientBuilderBeanPostProcessor(loadBalancerInterceptor, context);
+		}
+
 	}
 
 }

spring-cloud-commons/src/main/java/org/springframework/cloud/client/loadbalancer/LoadBalancerRequestTransformer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2023 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.
@@ -30,7 +30,7 @@
 public interface LoadBalancerRequestTransformer {
 
 	/**
-	 * Order for the load balancer request tranformer.
+	 * Order for the load balancer request transformer.
 	 */
 	int DEFAULT_ORDER = 0;
 

spring-cloud-commons/src/main/java/org/springframework/cloud/client/loadbalancer/LoadBalancerRestClientBuilderBeanPostProcessor.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2012-2023 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.cloud.client.loadbalancer;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.config.BeanPostProcessor;
+import org.springframework.context.ApplicationContext;
+import org.springframework.http.client.ClientHttpRequestInterceptor;
+import org.springframework.web.client.RestClient;
+
+/**
+ * @author Olga Maciaszek-Sharma
+ */
+// TODO: make deferring?
+public class LoadBalancerRestClientBuilderBeanPostProcessor implements BeanPostProcessor {
+
+	private final ClientHttpRequestInterceptor loadBalancerInterceptor;
+
+	private final ApplicationContext context;
+
+	public LoadBalancerRestClientBuilderBeanPostProcessor(ClientHttpRequestInterceptor loadBalancerInterceptor,
+			ApplicationContext context) {
+		this.loadBalancerInterceptor = loadBalancerInterceptor;
+		this.context = context;
+	}
+
+	@Override
+	public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
+		if (bean instanceof RestClient.Builder) {
+			if (context.findAnnotationOnBean(beanName, LoadBalanced.class) == null) {
+				return bean;
+			}
+			((RestClient.Builder) bean).requestInterceptor(loadBalancerInterceptor);
+		}
+		return bean;
+	}
+
+}