Added support for multiple reporters

docs/src/main/asciidoc/intro.adoc

@@ -417,6 +417,18 @@ dependencies {
 <2> Add the dependency to `spring-cloud-starter-zipkin`. That way, all nested dependencies get downloaded.
 <3> To automatically configure RabbitMQ, add the `spring-rabbit` dependency.
 
+=== Overriding the auto-configuration of Zipkin
+
+Spring Cloud Sleuth supports sending traces to multiple tracing systems as of version 2.1.0.
+In order to get this to work, every tracing system needs to have a `Reporter<Span>` and `Sender`.
+If you want to override the provided beans you need to give them a specific name.
+To do this you can use respectively `ZipkinAutoConfiguration.REPORTER_BEAN_NAME` and `ZipkinAutoConfiguration.SENDER_BEAN_NAME`.
+
+[source,java]
+----
+include::../../../../spring-cloud-sleuth-zipkin/src/test/java/org/springframework/cloud/sleuth/zipkin2/ZipkinAutoConfigurationTests.java[tags=override_default_beans,indent=0]
+----
+
 == Additional Resources
 
 You can watch a video of https://twitter.com/reshmi9k[Reshmi Krishna] and https://twitter.com/mgrzejszczak[Marcin Grzejszczak] talking about Spring Cloud

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2018 the original author or authors.
+ * Copyright 2013-2019 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.
@@ -32,7 +32,9 @@
 import brave.sampler.Sampler;
 import org.springframework.util.StringUtils;
 import zipkin2.Span;
+import zipkin2.reporter.InMemoryReporterMetrics;
 import zipkin2.reporter.Reporter;
+import zipkin2.reporter.ReporterMetrics;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
@@ -51,6 +53,7 @@
  *
  * @author Spencer Gibb
  * @author Marcin Grzejszczak
+ * @author Tim Ysewyn
  * @since 2.0.0
  */
 @Configuration
@@ -68,6 +71,9 @@ public class TraceAutoConfiguration {
 	 */
 	public static final String DEFAULT_SERVICE_NAME = "default";
 
+	@Autowired(required = false)
+	List<Reporter<zipkin2.Span>> spanReporters = new ArrayList<>();
+
 	@Autowired(required = false)
 	List<SpanAdjuster> spanAdjusters = new ArrayList<>();
 
@@ -86,13 +92,12 @@ public class TraceAutoConfiguration {
 	Tracing tracing(
 			@Value("${spring.zipkin.service.name:${spring.application.name:default}}") String serviceName,
 			Propagation.Factory factory, CurrentTraceContext currentTraceContext,
-			Reporter<zipkin2.Span> reporter, Sampler sampler, ErrorParser errorParser,
-			SleuthProperties sleuthProperties) {
+			Sampler sampler, ErrorParser errorParser, SleuthProperties sleuthProperties) {
 		Tracing.Builder builder = Tracing.newBuilder().sampler(sampler)
 				.errorParser(errorParser)
 				.localServiceName(StringUtils.isEmpty(serviceName) ? DEFAULT_SERVICE_NAME : serviceName)
 				.propagationFactory(factory).currentTraceContext(currentTraceContext)
-				.spanReporter(adjustedReporter(reporter))
+				.spanReporter(compositeReporter())
 				.traceId128Bit(sleuthProperties.isTraceId128())
 				.supportsJoin(sleuthProperties.isSupportsJoin());
 		for (FinishedSpanHandler finishedSpanHandlerFactory : this.finishedSpanHandlers) {
@@ -101,13 +106,15 @@ Tracing tracing(
 		return builder.build();
 	}
 
-	private Reporter<zipkin2.Span> adjustedReporter(Reporter<zipkin2.Span> delegate) {
+	private Reporter<zipkin2.Span> compositeReporter() {
 		return (span) -> {
 			Span spanToAdjust = span;
 			for (SpanAdjuster spanAdjuster : this.spanAdjusters) {
 				spanToAdjust = spanAdjuster.adjust(spanToAdjust);
 			}
-			delegate.report(spanToAdjust);
+			for (Reporter<zipkin2.Span> spanReporter : this.spanReporters) {
+				spanReporter.report(spanToAdjust);
+			}
 		};
 	}
 
@@ -173,6 +180,12 @@ CurrentTraceContext.Builder sleuthCurrentTraceContextBuilder() {
 		return ThreadLocalCurrentTraceContext.newBuilder();
 	}
 
+	@Bean
+	@ConditionalOnMissingBean
+	ReporterMetrics sleuthReporterMetrics() {
+		return new InMemoryReporterMetrics();
+	}
+
 	@Bean
 	@ConditionalOnMissingBean
 	Reporter<zipkin2.Span> noOpSpanReporter() {

spring-cloud-sleuth-zipkin/src/main/java/org/springframework/cloud/sleuth/zipkin2/ZipkinAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2018 the original author or authors.
+ * Copyright 2013-2019 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.
@@ -19,14 +19,13 @@
 import java.util.concurrent.TimeUnit;
 
 import zipkin2.Span;
-import zipkin2.codec.BytesEncoder;
 import zipkin2.reporter.AsyncReporter;
-import zipkin2.reporter.InMemoryReporterMetrics;
 import zipkin2.reporter.Reporter;
 import zipkin2.reporter.ReporterMetrics;
 import zipkin2.reporter.Sender;
 
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.AutoConfigureBefore;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -55,40 +54,41 @@
  * {@link DefaultZipkinRestTemplateCustomizer} adds the GZip compression.
  *
  * @author Spencer Gibb
+ * @author Tim Ysewyn
  * @since 1.0.0
  * @see SamplerAutoConfiguration
  * @see ZipkinRestTemplateCustomizer
  * @see DefaultZipkinRestTemplateCustomizer
  */
 @Configuration
 @EnableConfigurationProperties(ZipkinProperties.class)
-@ConditionalOnProperty(value = "spring.zipkin.enabled", matchIfMissing = true)
+@ConditionalOnProperty(value = { "spring.sleuth.enabled",
+		"spring.zipkin.enabled" }, matchIfMissing = true)
 @AutoConfigureBefore(TraceAutoConfiguration.class)
 @AutoConfigureAfter(name = "org.springframework.cloud.autoconfigure.RefreshAutoConfiguration")
 @Import({ ZipkinSenderConfigurationImportSelector.class, SamplerAutoConfiguration.class })
 public class ZipkinAutoConfiguration {
 
 	/**
-	 * Accepts a sender so you can plug-in any standard one. Returns a Reporter so you can
-	 * also replace with a standard one.
+	 * Zipkin reporter bean name. Name of the bean matters for supporting multiple tracing
+	 * systems.
 	 */
-	@Bean
-	@ConditionalOnMissingBean
+	public static final String REPORTER_BEAN_NAME = "zipkinReporter";
+
+	/**
+	 * Zipkin sender bean name. Name of the bean matters for supporting multiple tracing
+	 * systems.
+	 */
+	public static final String SENDER_BEAN_NAME = "zipkinSender";
+
+	@Bean(REPORTER_BEAN_NAME)
+	@ConditionalOnMissingBean(name = REPORTER_BEAN_NAME)
 	public Reporter<Span> reporter(ReporterMetrics reporterMetrics,
-			ZipkinProperties zipkin, Sender sender, BytesEncoder<Span> spanBytesEncoder) {
-		return AsyncReporter.builder(sender).queuedMaxSpans(1000) // historical
-																	// constraint. Note:
-																	// AsyncReporter
-																	// supports memory
-																	// bounds
+			ZipkinProperties zipkin, @Qualifier(SENDER_BEAN_NAME) Sender sender) {
+		// historical constraint. Note: AsyncReporter supports memory bounds
+		return AsyncReporter.builder(sender).queuedMaxSpans(1000)
 				.messageTimeout(zipkin.getMessageTimeout(), TimeUnit.SECONDS)
-				.metrics(reporterMetrics).build(spanBytesEncoder);
-	}
-
-	@Bean
-	@ConditionalOnMissingBean
-	public BytesEncoder<Span> spanBytesEncoder(ZipkinProperties zipkinProperties) {
-		return zipkinProperties.getEncoder();
+				.metrics(reporterMetrics).build(zipkin.getEncoder());
 	}
 
 	@Bean
@@ -98,12 +98,6 @@ public ZipkinRestTemplateCustomizer zipkinRestTemplateCustomizer(
 		return new DefaultZipkinRestTemplateCustomizer(zipkinProperties);
 	}
 
-	@Bean
-	@ConditionalOnMissingBean
-	ReporterMetrics sleuthReporterMetrics() {
-		return new InMemoryReporterMetrics();
-	}
-
 	@Configuration
 	@ConditionalOnMissingBean(EndpointLocator.class)
 	@ConditionalOnProperty(value = "spring.zipkin.locator.discovery.enabled", havingValue = "false", matchIfMissing = true)

spring-cloud-sleuth-zipkin/src/main/java/org/springframework/cloud/sleuth/zipkin2/ZipkinBackwardsCompatibilityAutoConfiguration.java

@@ -0,0 +1,145 @@
+/*
+ * Copyright 2013-2019 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.zipkin2;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+import zipkin2.Span;
+import zipkin2.codec.BytesEncoder;
+import zipkin2.reporter.AsyncReporter;
+import zipkin2.reporter.InMemoryReporterMetrics;
+import zipkin2.reporter.Reporter;
+import zipkin2.reporter.ReporterMetrics;
+import zipkin2.reporter.Sender;
+
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.boot.autoconfigure.AutoConfigureAfter;
+import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
+import org.springframework.cloud.sleuth.autoconfig.TraceAutoConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.context.annotation.Conditional;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.ConfigurationCondition;
+import org.springframework.core.type.AnnotatedTypeMetadata;
+import org.springframework.util.Assert;
+
+/**
+ * {@link org.springframework.boot.autoconfigure.EnableAutoConfiguration
+ * Auto-configuration} that will provide backwards compatibility to be able to support
+ * multiple tracing systems on the classpath.
+ *
+ * Needs to be auto-configured before {@link ZipkinAutoConfiguration} in order to create a
+ * {@link Reporter<Span> span reporter} if needed.
+ *
+ * @author Tim Ysewyn
+ * @since 2.1.0
+ * @see ZipkinAutoConfiguration
+ * @deprecated
+ */
+@Configuration
+@ConditionalOnProperty(value = { "spring.sleuth.enabled" }, matchIfMissing = true)
+@AutoConfigureAfter({ ZipkinAutoConfiguration.class })
+@Deprecated
+class ZipkinBackwardsCompatibilityAutoConfiguration {
+
+	/**
+	 * Reporter that is depending on a {@link Sender} bean which is created in another
+	 * auto-configuration than {@link ZipkinAutoConfiguration}.
+	 */
+	@Bean
+	@Conditional(BackwardsCompatibilityCondition.class)
+	@Deprecated
+	Reporter<Span> reporter(ReporterMetrics reporterMetrics, ZipkinProperties zipkin,
+			BytesEncoder<Span> spanBytesEncoder, DefaultListableBeanFactory beanFactory) {
+		List<String> beanNames = new ArrayList<>(
+				Arrays.asList(beanFactory.getBeanNamesForType(Sender.class)));
+		beanNames.remove(ZipkinAutoConfiguration.SENDER_BEAN_NAME);
+		Sender sender = (Sender) beanFactory.getBean(beanNames.get(0));
+		// historical constraint. Note: AsyncReporter supports memory bounds
+		return AsyncReporter.builder(sender).queuedMaxSpans(1000)
+				.messageTimeout(zipkin.getMessageTimeout(), TimeUnit.SECONDS)
+				.metrics(reporterMetrics).build(spanBytesEncoder);
+	}
+
+	/**
+	 * Only used for creating a reporter bean with the method above
+	 * @deprecated
+	 */
+	@Bean
+	@ConditionalOnMissingBean
+	@Deprecated
+	BytesEncoder<Span> spanBytesEncoder(ZipkinProperties zipkinProperties) {
+		return zipkinProperties.getEncoder();
+	}
+
+	/**
+	 * Deprecated because this is moved to {@link TraceAutoConfiguration}. Left for
+	 * backwards compatibility reasons.
+	 * @deprecated
+	 */
+	@Bean
+	@ConditionalOnMissingBean
+	@Deprecated
+	ReporterMetrics zipkinReporterMetrics() {
+		return new InMemoryReporterMetrics();
+	}
+
+	static class BackwardsCompatibilityCondition extends SpringBootCondition
+			implements ConfigurationCondition {
+
+		@Override
+		public ConfigurationPhase getConfigurationPhase() {
+			return ConfigurationPhase.REGISTER_BEAN;
+		}
+
+		@Override
+		public ConditionOutcome getMatchOutcome(ConditionContext context,
+				AnnotatedTypeMetadata metadata) {
+			Assert.isInstanceOf(DefaultListableBeanFactory.class,
+					context.getBeanFactory());
+			DefaultListableBeanFactory listableBeanFactory = (DefaultListableBeanFactory) context
+					.getBeanFactory();
+			int foundSenders = listableBeanFactory
+					.getBeanNamesForType(Sender.class).length;
+
+			// Previously we supported 1 Sender bean at a time
+			// which could be overridden by another auto-configuration.
+			// Now we support both the overridden bean and our default zipkinSender bean.
+			if (foundSenders < 2) {
+				return ConditionOutcome.noMatch(
+						"We don't support backwards compatibility for more than 2 Sender beans");
+			}
+			int foundReporters = listableBeanFactory
+					.getBeanNamesForType(Reporter.class).length;
+			// Check if we need to provide a Reporter bean for the overridden Sender bean
+			if (foundReporters == foundSenders) {
+				return ConditionOutcome.noMatch(
+						"Both tracing systems already define their own Reporter bean");
+			}
+			return ConditionOutcome.match();
+		}
+
+	}
+
+}

spring-cloud-sleuth-zipkin/src/main/java/org/springframework/cloud/sleuth/zipkin2/sender/ZipkinKafkaSenderConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2018 the original author or authors.
+ * Copyright 2013-2019 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.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.kafka.KafkaProperties;
+import org.springframework.cloud.sleuth.zipkin2.ZipkinAutoConfiguration;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
@@ -34,15 +35,15 @@
 @Configuration
 @ConditionalOnClass(ByteArraySerializer.class)
 @ConditionalOnBean(KafkaProperties.class)
-@ConditionalOnMissingBean(Sender.class)
+@ConditionalOnMissingBean(name = ZipkinAutoConfiguration.SENDER_BEAN_NAME)
 @Conditional(ZipkinSenderCondition.class)
 @ConditionalOnProperty(value = "spring.zipkin.sender.type", havingValue = "kafka")
 class ZipkinKafkaSenderConfiguration {
 
 	@Value("${spring.zipkin.kafka.topic:zipkin}")
 	private String topic;
 
-	@Bean
+	@Bean(ZipkinAutoConfiguration.SENDER_BEAN_NAME)
 	Sender kafkaSender(KafkaProperties config) {
 		Map<String, Object> properties = config.buildProducerProperties();
 		properties.put("key.serializer", ByteArraySerializer.class.getName());