Adapted new configuration to support backwards compatibility in case another tracing system extends from spring-cloud-sleuth-zipkin (like spring-cloud-gcp-trace)

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

@@ -19,9 +19,7 @@ package org.springframework.cloud.sleuth.zipkin2;
 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;
@@ -86,18 +84,11 @@ public class ZipkinAutoConfiguration {
 	@Bean(REPORTER_BEAN_NAME)
 	@ConditionalOnMissingBean(name = REPORTER_BEAN_NAME)
 	public Reporter<Span> reporter(ReporterMetrics reporterMetrics,
-			ZipkinProperties zipkin, @Qualifier(SENDER_BEAN_NAME) Sender sender,
-			BytesEncoder<Span> spanBytesEncoder) {
+			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
@@ -107,18 +98,6 @@ public class ZipkinAutoConfiguration {
 		return new DefaultZipkinRestTemplateCustomizer(zipkinProperties);
 	}
 
-	/**
-	 * Deprecated because this is moved to {@link TraceAutoConfiguration}. Left for
-	 * backwards compatibility reasons.
-	 * @deprecated
-	 */
-	@Bean
-	@ConditionalOnMissingBean
-	@Deprecated
-	ReporterMetrics zipkinReporterMetrics() {
-		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 +1,149 @@
+/*
+ * 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.Collections;
+import java.util.List;
+import java.util.Map;
+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",
+		"spring.zipkin.enabled" }, matchIfMissing = true)
+@AutoConfigureAfter({ ZipkinAutoConfiguration.class })
+@Deprecated
+public 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
+	public 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
+	public 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

@@ -35,7 +35,7 @@ import zipkin2.reporter.kafka11.KafkaSender;
 @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 {

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

@@ -30,7 +30,7 @@ import zipkin2.reporter.amqp.RabbitMQSender;
 
 @Configuration
 @ConditionalOnBean(CachingConnectionFactory.class)
-@ConditionalOnMissingBean(Sender.class)
+@ConditionalOnMissingBean(name = ZipkinAutoConfiguration.SENDER_BEAN_NAME)
 @Conditional(ZipkinSenderCondition.class)
 class ZipkinRabbitSenderConfiguration {
 

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

@@ -43,7 +43,7 @@ import org.springframework.web.client.RestTemplate;
 import zipkin2.reporter.Sender;
 
 @Configuration
-@ConditionalOnMissingBean(Sender.class)
+@ConditionalOnMissingBean(name = ZipkinAutoConfiguration.SENDER_BEAN_NAME)
 @Conditional(ZipkinSenderCondition.class)
 @EnableConfigurationProperties(ZipkinSenderProperties.class)
 class ZipkinRestTemplateSenderConfiguration {
@@ -52,7 +52,6 @@ class ZipkinRestTemplateSenderConfiguration {
 	ZipkinUrlExtractor extractor;
 
 	@Bean(ZipkinAutoConfiguration.SENDER_BEAN_NAME)
-	@ConditionalOnMissingBean(name = ZipkinAutoConfiguration.SENDER_BEAN_NAME)
 	public Sender restTemplateSender(ZipkinProperties zipkin,
 			ZipkinRestTemplateCustomizer zipkinRestTemplateCustomizer) {
 		RestTemplate restTemplate = new ZipkinRestTemplateWrapper(zipkin, this.extractor);

spring-cloud-sleuth-zipkin/src/main/resources/META-INF/spring.factories

@@ -1,3 +1,4 @@
 # Auto Configuration
 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
-org.springframework.cloud.sleuth.zipkin2.ZipkinAutoConfiguration
+org.springframework.cloud.sleuth.zipkin2.ZipkinAutoConfiguration,\
+  org.springframework.cloud.sleuth.zipkin2.ZipkinBackwardsCompatibilityAutoConfiguration

spring-cloud-sleuth-zipkin/src/test/java/org/springframework/cloud/sleuth/zipkin2/ZipkinAutoConfigurationTests.java

@@ -79,7 +79,7 @@ public class ZipkinAutoConfigurationTests {
 				this.server.url("/").toString());
 		this.context.register(ZipkinAutoConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class, TraceAutoConfiguration.class,
-				Config.class);
+				Config.class, ZipkinBackwardsCompatibilityAutoConfiguration.class);
 		this.context.refresh();
 		Span span = this.context.getBean(Tracing.class).tracer().nextSpan().name("foo")
 				.tag("foo", "bar").start();
@@ -106,7 +106,7 @@ public class ZipkinAutoConfigurationTests {
 		environment().setProperty("spring.zipkin.encoder", "JSON_V1");
 		this.context.register(ZipkinAutoConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class, TraceAutoConfiguration.class,
-				Config.class);
+				Config.class, ZipkinBackwardsCompatibilityAutoConfiguration.class);
 		this.context.refresh();
 		Span span = this.context.getBean(Tracing.class).tracer().nextSpan().name("foo")
 				.tag("foo", "bar").start();
@@ -124,9 +124,11 @@ public class ZipkinAutoConfigurationTests {
 	public void overrideRabbitMQQueue() throws Exception {
 		this.context = new AnnotationConfigApplicationContext();
 		environment().setProperty("spring.zipkin.rabbitmq.queue", "zipkin2");
+		environment().setProperty("spring.zipkin.sender.type", "rabbit");
 		this.context.register(PropertyPlaceholderAutoConfiguration.class,
 				RabbitAutoConfiguration.class, ZipkinAutoConfiguration.class,
-				TraceAutoConfiguration.class);
+				TraceAutoConfiguration.class,
+				ZipkinBackwardsCompatibilityAutoConfiguration.class);
 		this.context.refresh();
 
 		then(this.context.getBean(Sender.class)).isInstanceOf(RabbitMQSender.class);
@@ -141,7 +143,8 @@ public class ZipkinAutoConfigurationTests {
 		environment().setProperty("spring.zipkin.sender.type", "kafka");
 		this.context.register(PropertyPlaceholderAutoConfiguration.class,
 				KafkaAutoConfiguration.class, ZipkinAutoConfiguration.class,
-				TraceAutoConfiguration.class);
+				TraceAutoConfiguration.class,
+				ZipkinBackwardsCompatibilityAutoConfiguration.class);
 		this.context.refresh();
 
 		then(this.context.getBean(Sender.class)).isInstanceOf(KafkaSender.class);
@@ -155,7 +158,8 @@ public class ZipkinAutoConfigurationTests {
 		environment().setProperty("spring.zipkin.sender.type", "web");
 		this.context.register(PropertyPlaceholderAutoConfiguration.class,
 				RabbitAutoConfiguration.class, KafkaAutoConfiguration.class,
-				ZipkinAutoConfiguration.class, TraceAutoConfiguration.class);
+				ZipkinAutoConfiguration.class, TraceAutoConfiguration.class,
+				ZipkinBackwardsCompatibilityAutoConfiguration.class);
 		this.context.refresh();
 
 		then(this.context.getBean(Sender.class).getClass().getName())
@@ -170,7 +174,8 @@ public class ZipkinAutoConfigurationTests {
 		environment().setProperty("spring.zipkin.sender.type", "WEB");
 		this.context.register(PropertyPlaceholderAutoConfiguration.class,
 				RabbitAutoConfiguration.class, KafkaAutoConfiguration.class,
-				ZipkinAutoConfiguration.class, TraceAutoConfiguration.class);
+				ZipkinAutoConfiguration.class, TraceAutoConfiguration.class,
+				ZipkinBackwardsCompatibilityAutoConfiguration.class);
 		this.context.refresh();
 
 		then(this.context.getBean(Sender.class).getClass().getName())
@@ -184,7 +189,8 @@ public class ZipkinAutoConfigurationTests {
 		this.context = new AnnotationConfigApplicationContext();
 		this.context.register(PropertyPlaceholderAutoConfiguration.class,
 				RabbitAutoConfiguration.class, KafkaAutoConfiguration.class,
-				ZipkinAutoConfiguration.class, TraceAutoConfiguration.class);
+				ZipkinAutoConfiguration.class, TraceAutoConfiguration.class,
+				ZipkinBackwardsCompatibilityAutoConfiguration.class);
 		this.context.refresh();
 
 		then(this.context.getBean(Sender.class)).isInstanceOf(RabbitMQSender.class);
@@ -199,7 +205,8 @@ public class ZipkinAutoConfigurationTests {
 				this.server.url("/").toString());
 		this.context.register(ZipkinAutoConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class, TraceAutoConfiguration.class,
-				Config.class, MultipleReportersConfig.class);
+				Config.class, MultipleReportersConfig.class,
+				ZipkinBackwardsCompatibilityAutoConfiguration.class);
 		this.context.refresh();
 
 		then(this.context.getBeansOfType(Sender.class)).hasSize(2);
@@ -226,12 +233,33 @@ public class ZipkinAutoConfigurationTests {
 		Awaitility.await().untilAsserted(() -> then(sender.isSpanSent()).isTrue());
 	}
 
+	@Test
+	public void supportsMultipleReportersWithBackwardsCompatibilty() throws Exception {
+		this.context = new AnnotationConfigApplicationContext();
+		environment().setProperty("spring.zipkin.base-url",
+				this.server.url("/").toString());
+		this.context.register(ZipkinAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class, TraceAutoConfiguration.class,
+				Config.class, BackwardsCompatibilityConfig.class,
+				ZipkinBackwardsCompatibilityAutoConfiguration.class);
+		this.context.refresh();
+
+		then(this.context.getBeansOfType(Sender.class)).hasSize(2);
+		then(this.context.getBeansOfType(Sender.class))
+				.containsKeys(ZipkinAutoConfiguration.SENDER_BEAN_NAME, "rabbitSender");
+
+		then(this.context.getBeansOfType(Reporter.class)).hasSize(2);
+		then(this.context.getBeansOfType(Reporter.class))
+				.containsKeys(ZipkinAutoConfiguration.REPORTER_BEAN_NAME, "reporter");
+	}
+
 	@Test
 	public void shouldOverrideDefaultBeans() {
 		this.context = new AnnotationConfigApplicationContext();
 		this.context.register(ZipkinAutoConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class, TraceAutoConfiguration.class,
-				Config.class, MyConfig.class);
+				Config.class, MyConfig.class,
+				ZipkinBackwardsCompatibilityAutoConfiguration.class);
 		this.context.refresh();
 
 		then(this.context.getBeansOfType(Sender.class)).hasSize(1);
@@ -337,6 +365,16 @@ public class ZipkinAutoConfigurationTests {
 
 	}
 
+	@Configuration
+	protected static class BackwardsCompatibilityConfig {
+
+		@Bean
+		Sender rabbitSender() {
+			return RabbitMQSender.create("localhost");
+		}
+
+	}
+
 	// tag::override_default_beans[]
 
 	@Configuration