wrapping all rest templates via BPP; fixes gh-846

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/client/TraceWebClientAutoConfiguration.java

@@ -18,12 +18,9 @@ package org.springframework.cloud.sleuth.instrument.web.client;
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Map;
-import javax.annotation.PostConstruct;
 
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanFactory;
-import org.springframework.beans.factory.BeanFactoryUtils;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
@@ -37,7 +34,6 @@ import org.springframework.cloud.sleuth.Tracer;
 import org.springframework.cloud.sleuth.instrument.web.HttpSpanInjector;
 import org.springframework.cloud.sleuth.instrument.web.HttpTraceKeysInjector;
 import org.springframework.cloud.sleuth.instrument.web.TraceWebAutoConfiguration;
-import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.annotation.Order;
@@ -72,9 +68,6 @@ public class TraceWebClientAutoConfiguration {
 	@Configuration
 	protected static class TraceInterceptorConfiguration {
 
-		@Autowired
-		private ApplicationContext applicationContext;
-
 		@Autowired
 		private TraceRestTemplateInterceptor traceRestTemplateInterceptor;
 
@@ -84,15 +77,9 @@ public class TraceWebClientAutoConfiguration {
 			return new TraceRestTemplateCustomizer(this.traceRestTemplateInterceptor);
 		}
 
-		@PostConstruct
-		public void init() {
-			Map<String, RestTemplate> restTemplates = BeanFactoryUtils
-					.beansOfTypeIncludingAncestors(this.applicationContext,
-							RestTemplate.class);
-			for (RestTemplate restTemplate : restTemplates.values()) {
-				new RestTemplateInterceptorInjector(
-						this.traceRestTemplateInterceptor).inject(restTemplate);
-			}
+		@Bean
+		TraceRestTemplateBPP traceRestTemplateBPP(BeanFactory beanFactory) {
+			return new TraceRestTemplateBPP(beanFactory);
 		}
 	}
 
@@ -183,6 +170,37 @@ class TraceRestTemplateCustomizer implements RestTemplateCustomizer {
 	}
 }
 
+class TraceRestTemplateBPP implements BeanPostProcessor {
+
+	private final BeanFactory beanFactory;
+	private TraceRestTemplateInterceptor interceptor;
+
+	TraceRestTemplateBPP(BeanFactory beanFactory) {
+		this.beanFactory = beanFactory;
+	}
+
+	@Override public Object postProcessBeforeInitialization(Object bean, String beanName)
+			throws BeansException {
+		return bean;
+	}
+
+	@Override public Object postProcessAfterInitialization(Object bean, String beanName)
+			throws BeansException {
+		if (bean instanceof RestTemplate)  {
+			RestTemplate rt = (RestTemplate) bean;
+			new RestTemplateInterceptorInjector(interceptor()).inject(rt);
+		}
+		return bean;
+	}
+
+	private TraceRestTemplateInterceptor interceptor() {
+		if (this.interceptor == null) {
+			this.interceptor = this.beanFactory.getBean(TraceRestTemplateInterceptor.class);
+		}
+		return this.interceptor;
+	}
+}
+
 class TraceUserInfoRestTemplateCustomizer implements UserInfoRestTemplateCustomizer {
 
 	private final BeanFactory beanFactory;

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/client/GH846Test.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2013-2018 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
+ *
+ *      http://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.sleuth.instrument.web.client;
+
+import javax.annotation.PostConstruct;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.client.ClientHttpRequestInterceptor;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.web.client.RestTemplate;
+
+@SpringBootTest(classes = GH846Test.App.class, webEnvironment=WebEnvironment.NONE)
+@RunWith(SpringRunner.class)
+public class GH846Test {
+
+	@Autowired
+	private MyBean myBean;
+	
+	@Test
+	public void doit() throws Exception {
+		int count = myBean.listAndCount();
+		Assert.assertEquals("Change detected in RestTemplate interceptor *after* @PostConstruct", count, myBean.getCountAtPostConstruct());
+	}
+	
+	@EnableAutoConfiguration
+	@Configuration
+	static class App {
+		@Bean
+		public RestTemplate myRestTemplate() {
+			return new RestTemplate();
+		}
+		
+		@Bean
+		public MyBean myBean() {
+			return new MyBean();
+		}
+	}
+
+	
+	static class MyBean {
+		@Autowired
+		private RestTemplate restTemplate;
+		
+		/** Number of interceptors registered in the RestTemplate during @PostConstruct */ 
+		private int countAtPostConstruct;
+		
+		@PostConstruct
+		public void init() {
+			countAtPostConstruct = listAndCount();
+		}
+		
+		public int listAndCount() {
+			for(ClientHttpRequestInterceptor interceptor: restTemplate.getInterceptors()) {
+				System.out.println(interceptor);
+			}
+			return restTemplate.getInterceptors().size();
+		}
+
+		public int getCountAtPostConstruct() {
+			return countAtPostConstruct;
+		}
+	}
+}