Ensure that BPP dependencies are not created too early

The FeignBeanPostProcessor was causing other things to misbehave
by forcing early instantiation of all its dependencies. One of those
is a @MessageEndpoint when Sleuth Stream is in use, and the annotation
wasn't being processed because the bean was processed too early.

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/autoconfig/TraceAutoConfiguration.java

@@ -61,7 +61,7 @@ public class TraceAutoConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean(Tracer.class)
-	public DefaultTracer traceManager(Sampler sampler, Random random,
+	public DefaultTracer sleuthTracer(Sampler sampler, Random random,
 			SpanNamer spanNamer, SpanLogger spanLogger,
 			SpanReporter spanReporter) {
 		return new DefaultTracer(sampler, random, spanNamer, spanLogger,

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

@@ -17,6 +17,7 @@
 package org.springframework.cloud.sleuth.instrument.web.client.feign;
 
 import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.cloud.sleuth.Tracer;
 
@@ -34,25 +35,33 @@ import feign.codec.Decoder;
  */
 final class FeignBeanPostProcessor implements BeanPostProcessor {
 
-	private final Tracer tracer;
+	private Tracer tracer;
+	private final BeanFactory beanFactory;
 
-	FeignBeanPostProcessor(Tracer tracer) {
-		this.tracer = tracer;
+	FeignBeanPostProcessor(BeanFactory beanFactory) {
+		this.beanFactory = beanFactory;
 	}
 
 	@Override
 	public Object postProcessBeforeInitialization(Object bean, String beanName)
 			throws BeansException {
 		if (bean instanceof Decoder && !(bean instanceof TraceFeignDecoder)) {
-			return new TraceFeignDecoder(this.tracer, (Decoder) bean);
+			return new TraceFeignDecoder(getTracer(), (Decoder) bean);
 		} else if (bean instanceof Retryer && !(bean instanceof TraceFeignRetryer)) {
-			return new TraceFeignRetryer(this.tracer, (Retryer) bean);
+			return new TraceFeignRetryer(getTracer(), (Retryer) bean);
 		} else if (bean instanceof Client && !(bean instanceof TraceFeignClient)) {
-			return new TraceFeignClient(this.tracer, (Client) bean);
+			return new TraceFeignClient(getTracer(), (Client) bean);
 		}
 		return bean;
 	}
 
+	private Tracer getTracer() {
+		if (this.tracer==null) {
+			this.tracer = this.beanFactory.getBean(Tracer.class);
+		}
+		return this.tracer;
+	}
+
 	@Override
 	public Object postProcessAfterInitialization(Object bean, String beanName)
 			throws BeansException {

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

@@ -19,6 +19,7 @@ package org.springframework.cloud.sleuth.instrument.web.client.feign;
 import java.io.IOException;
 import java.lang.reflect.Type;
 
+import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.ObjectFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
@@ -49,8 +50,8 @@ import feign.Response;
 import feign.codec.Decoder;
 
 /**
- * {@link org.springframework.boot.autoconfigure.EnableAutoConfiguration Auto-configuration}
- * enables span information propagation when using Feign.
+ * {@link org.springframework.boot.autoconfigure.EnableAutoConfiguration
+ * Auto-configuration} enables span information propagation when using Feign.
  *
  * @author Marcin Grzejszczak
  *
@@ -74,33 +75,44 @@ public class TraceFeignClientAutoConfiguration {
 		return SleuthFeignBuilder.builder(tracer);
 	}
 
-	@Bean
-	@ConditionalOnProperty(name = "spring.sleuth.feign.processor.enabled", matchIfMissing = true)
-	FeignBeanPostProcessor feignBeanPostProcessor(Tracer tracer) {
-		return new FeignBeanPostProcessor(tracer);
+	@Configuration
+	protected static class FeignBeanPostProcessorConfiguration {
+
+		@Bean
+		@ConditionalOnProperty(name = "spring.sleuth.feign.processor.enabled", matchIfMissing = true)
+		FeignBeanPostProcessor feignBeanPostProcessor(BeanFactory beanFactory) {
+			return new FeignBeanPostProcessor(beanFactory);
+		}
+
 	}
 
 	@Bean
 	@Primary
 	Decoder feignDecoder(final Tracer tracer) {
-		return new TraceFeignDecoder(tracer, new ResponseEntityDecoder(new SpringDecoder(this.messageConverters)) {
-			@Override
-			public Object decode(Response response, Type type)
-					throws IOException, FeignException {
-					FeignRequestContext feignRequestContext = FeignRequestContext.getInstance();
-					FeignResponseHeadersHolder feignResponseHeadersHolder =
-							new FeignResponseHeadersHolder(response.headers());
-					feignResponseHeadersInjector().inject(feignRequestContext.getCurrentSpan(), feignResponseHeadersHolder);
-					return super.decode(Response.create(response.status(),
-							response.reason(), feignResponseHeadersHolder.responseHeaders,
-							response.body()), type);
-			}
-		});
+		return new TraceFeignDecoder(tracer,
+				new ResponseEntityDecoder(new SpringDecoder(this.messageConverters)) {
+					@Override
+					public Object decode(Response response, Type type)
+							throws IOException, FeignException {
+						FeignRequestContext feignRequestContext = FeignRequestContext
+								.getInstance();
+						FeignResponseHeadersHolder feignResponseHeadersHolder = new FeignResponseHeadersHolder(
+								response.headers());
+						feignResponseHeadersInjector().inject(
+								feignRequestContext.getCurrentSpan(),
+								feignResponseHeadersHolder);
+						return super.decode(
+								Response.create(response.status(), response.reason(),
+										feignResponseHeadersHolder.responseHeaders,
+										response.body()),
+								type);
+					}
+				});
 	}
 
 	/**
-	 * Sleuth {@link feign.RequestInterceptor} that either starts a new Span
-	 * or continues an existing one if a retry takes place.
+	 * Sleuth {@link feign.RequestInterceptor} that either starts a new Span or continues
+	 * an existing one if a retry takes place.
 	 */
 	@Bean
 	public RequestInterceptor traceIdRequestInterceptor(Tracer tracer) {

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/log/SleuthLogAutoConfiguration.java

@@ -18,12 +18,10 @@ package org.springframework.cloud.sleuth.log;
 
 import org.slf4j.MDC;
 import org.springframework.beans.factory.annotation.Value;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
-import org.springframework.cloud.sleuth.Tracer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 
@@ -38,7 +36,7 @@ import org.springframework.context.annotation.Configuration;
  * @since 1.0.0
  */
 @Configuration
-@ConditionalOnBean(Tracer.class)
+@ConditionalOnProperty(value="spring.sleuth.enabled", matchIfMissing=true)
 public class SleuthLogAutoConfiguration {
 
 	@Configuration

spring-cloud-sleuth-stream/src/main/java/org/springframework/cloud/sleuth/stream/SleuthStreamAutoConfiguration.java

@@ -72,7 +72,7 @@ public class SleuthStreamAutoConfiguration {
 	}
 
 	@Bean
-	public StreamSpanListener sleuthTracer(HostLocator endpointLocator,
+	public StreamSpanListener sleuthStreamSpanListener(HostLocator endpointLocator,
 			SpanMetricReporter spanMetricReporter) {
 		return new StreamSpanListener(endpointLocator, spanMetricReporter);
 	}