Remove cycles from auto configuration (#1196)

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

@@ -17,6 +17,7 @@
 package org.springframework.cloud.sleuth.autoconfig;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 import brave.CurrentSpanCustomizer;
@@ -37,6 +38,7 @@ import zipkin2.reporter.InMemoryReporterMetrics;
 import zipkin2.reporter.Reporter;
 import zipkin2.reporter.ReporterMetrics;
 
+import org.springframework.lang.Nullable;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -73,9 +75,6 @@ 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<>();
 
@@ -94,14 +93,15 @@ public class TraceAutoConfiguration {
 	Tracing tracing(
 			@Value("${spring.zipkin.service.name:${spring.application.name:default}}") String serviceName,
 			Propagation.Factory factory, CurrentTraceContext currentTraceContext,
-			Sampler sampler, ErrorParser errorParser, SleuthProperties sleuthProperties) {
+			Sampler sampler, ErrorParser errorParser, SleuthProperties sleuthProperties,
+			@Nullable List<Reporter<zipkin2.Span>> spanReporters) {
 		Tracing.Builder builder = Tracing.newBuilder().sampler(sampler)
 				.errorParser(errorParser)
 				.localServiceName(StringUtils.isEmpty(serviceName) ? DEFAULT_SERVICE_NAME
 						: serviceName)
 				.propagationFactory(factory).currentTraceContext(currentTraceContext)
-				.spanReporter(
-						new CompositeReporter(this.spanAdjusters, this.spanReporters))
+				.spanReporter(new CompositeReporter(this.spanAdjusters,
+						spanReporters != null ? spanReporters : Collections.emptyList()))
 				.traceId128Bit(sleuthProperties.isTraceId128())
 				.supportsJoin(sleuthProperties.isSupportsJoin());
 		for (FinishedSpanHandler finishedSpanHandlerFactory : this.finishedSpanHandlers) {

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

@@ -23,7 +23,6 @@ import brave.http.HttpClientParser;
 import brave.http.HttpSampler;
 import brave.http.HttpServerParser;
 import brave.http.HttpTracing;
-import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -32,6 +31,7 @@ import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.Ordered;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link org.springframework.boot.autoconfigure.EnableAutoConfiguration
@@ -49,34 +49,22 @@ public class TraceHttpAutoConfiguration {
 
 	static final int TRACING_FILTER_ORDER = Ordered.HIGHEST_PRECEDENCE + 5;
 
-	@Autowired
-	HttpClientParser clientParser;
-
-	@Autowired
-	HttpServerParser serverParser;
-
-	@Autowired
-	@ClientSampler
-	HttpSampler clientSampler;
-
-	@Autowired(required = false)
-	@ServerSampler
-	HttpSampler serverSampler;
-
 	@Bean
 	@ConditionalOnMissingBean
 	// NOTE: stable bean name as might be used outside sleuth
-	HttpTracing httpTracing(Tracing tracing, SkipPatternProvider provider) {
-		HttpSampler serverSampler = combineUserProvidedSamplerWithSkipPatternSampler(
-				provider);
-		return HttpTracing.newBuilder(tracing).clientParser(this.clientParser)
-				.serverParser(this.serverParser).clientSampler(this.clientSampler)
-				.serverSampler(serverSampler).build();
+	HttpTracing httpTracing(Tracing tracing, SkipPatternProvider provider,
+			HttpClientParser clientParser, HttpServerParser serverParser,
+			@ClientSampler HttpSampler clientSampler,
+			@Nullable @ServerSampler HttpSampler serverSampler) {
+		HttpSampler combinedSampler = combineUserProvidedSamplerWithSkipPatternSampler(
+				serverSampler, provider);
+		return HttpTracing.newBuilder(tracing).clientParser(clientParser)
+				.serverParser(serverParser).clientSampler(clientSampler)
+				.serverSampler(combinedSampler).build();
 	}
 
 	private HttpSampler combineUserProvidedSamplerWithSkipPatternSampler(
-			SkipPatternProvider provider) {
-		HttpSampler serverSampler = this.serverSampler;
+			HttpSampler serverSampler, SkipPatternProvider provider) {
 		SleuthHttpSampler skipPatternSampler = new SleuthHttpSampler(provider);
 		if (serverSampler == null) {
 			return skipPatternSampler;

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/autoconfig/TraceAutoConfigurationPropagationCustomizationTests.java

@@ -8,8 +8,11 @@ import org.assertj.core.api.BDDAssertions;
 import org.junit.Test;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.cloud.sleuth.instrument.web.TraceHttpAutoConfiguration;
+import org.springframework.cloud.sleuth.instrument.web.TraceWebAutoConfiguration;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.GenericApplicationContext;
 
 public class TraceAutoConfigurationPropagationCustomizationTests {
 
@@ -43,6 +46,18 @@ public class TraceAutoConfigurationPropagationCustomizationTests {
 				});
 	}
 
+	@Test
+	public void hasNoCycles() {
+		this.contextRunner
+				.withConfiguration(AutoConfigurations.of(TraceWebAutoConfiguration.class,
+						TraceHttpAutoConfiguration.class))
+				.withInitializer(c -> ((GenericApplicationContext) c)
+						.setAllowCircularReferences(false))
+				.run((context) -> {
+					BDDAssertions.then(context.isRunning()).isEqualTo(true);
+				});
+	}
+
 	@Test
 	public void allowsCustomizationOfBuilder() {
 		this.contextRunner.withPropertyValues("spring.sleuth.baggage-keys=my-baggage")