Support overriding OTel SpanExporters

See gh-35596

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/OpenTelemetryAutoConfiguration.java

@@ -133,16 +133,22 @@ public class OpenTelemetryAutoConfiguration {
 	}
 
 	@Bean
-	BatchSpanProcessor otelSpanProcessor(ObjectProvider<SpanExporter> spanExporters,
+	BatchSpanProcessor otelSpanProcessor(SpanExporters spanExporters,
 			ObjectProvider<SpanExportingPredicate> spanExportingPredicates, ObjectProvider<SpanReporter> spanReporters,
 			ObjectProvider<SpanFilter> spanFilters, ObjectProvider<MeterProvider> meterProvider) {
-		BatchSpanProcessorBuilder builder = BatchSpanProcessor.builder(new CompositeSpanExporter(
-				spanExporters.orderedStream().toList(), spanExportingPredicates.orderedStream().toList(),
-				spanReporters.orderedStream().toList(), spanFilters.orderedStream().toList()));
+		BatchSpanProcessorBuilder builder = BatchSpanProcessor.builder(
+				new CompositeSpanExporter(spanExporters.getList(), spanExportingPredicates.orderedStream().toList(),
+						spanReporters.orderedStream().toList(), spanFilters.orderedStream().toList()));
 		meterProvider.ifAvailable(builder::setMeterProvider);
 		return builder.build();
 	}
 
+	@Bean
+	@ConditionalOnMissingBean
+	SpanExporters spanExporters(ObjectProvider<SpanExporter> spanExporters) {
+		return SpanExporters.of(spanExporters.orderedStream().collect(Collectors.toList()));
+	}
+
 	@Bean
 	@ConditionalOnMissingBean
 	Tracer otelTracer(OpenTelemetry openTelemetry) {

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/SpanExporters.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2012-2023 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
+ *
+ *      https://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.boot.actuate.autoconfigure.tracing;
+
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Spliterator;
+
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+
+/**
+ * A collection of {@link SpanExporter span exporters}.
+ *
+ * @author Moritz Halbritter
+ * @since 3.2.0
+ */
+public interface SpanExporters extends Iterable<SpanExporter> {
+
+	/**
+	 * Returns the list of {@link SpanExporter span exporters}.
+	 * @return the list of span exporters
+	 */
+	List<SpanExporter> getList();
+
+	@Override
+	default Iterator<SpanExporter> iterator() {
+		return getList().iterator();
+	}
+
+	@Override
+	default Spliterator<SpanExporter> spliterator() {
+		return getList().spliterator();
+	}
+
+	/**
+	 * Constructs a {@link SpanExporters} instance with the given list of
+	 * {@link SpanExporter span exporters}.
+	 * @param spanExporters the list of span exporters
+	 * @return the constructed {@link SpanExporters} instance
+	 */
+	static SpanExporters of(List<SpanExporter> spanExporters) {
+		return () -> spanExporters;
+	}
+
+	/**
+	 * Constructs a {@link SpanExporters} instance with the given {@link SpanExporter span
+	 * exporters}.
+	 * @param spanExporters the span exporters
+	 * @return the constructed {@link SpanExporters} instance
+	 */
+	static SpanExporters of(SpanExporter... spanExporters) {
+		return of(Arrays.asList(spanExporters));
+	}
+
+}

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/tracing/OpenTelemetryAutoConfigurationTests.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.actuate.autoconfigure.tracing;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 
 import io.micrometer.tracing.SpanCustomizer;
@@ -35,9 +36,12 @@ import io.opentelemetry.api.trace.propagation.W3CTraceContextPropagator;
 import io.opentelemetry.context.propagation.ContextPropagators;
 import io.opentelemetry.context.propagation.TextMapPropagator;
 import io.opentelemetry.extension.trace.propagation.B3Propagator;
+import io.opentelemetry.sdk.common.CompletableResultCode;
 import io.opentelemetry.sdk.trace.SdkTracerProvider;
 import io.opentelemetry.sdk.trace.SpanLimits;
 import io.opentelemetry.sdk.trace.SpanProcessor;
+import io.opentelemetry.sdk.trace.data.SpanData;
+import io.opentelemetry.sdk.trace.export.SpanExporter;
 import io.opentelemetry.sdk.trace.samplers.Sampler;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -88,6 +92,7 @@ class OpenTelemetryAutoConfigurationTests {
 			assertThat(context).hasSingleBean(TextMapPropagator.class);
 			assertThat(context).hasSingleBean(OtelSpanCustomizer.class);
 			assertThat(context).hasSingleBean(SpanProcessors.class);
+			assertThat(context).hasSingleBean(SpanExporters.class);
 		});
 	}
 
@@ -119,6 +124,7 @@ class OpenTelemetryAutoConfigurationTests {
 			assertThat(context).doesNotHaveBean(TextMapPropagator.class);
 			assertThat(context).doesNotHaveBean(OtelSpanCustomizer.class);
 			assertThat(context).doesNotHaveBean(SpanProcessors.class);
+			assertThat(context).doesNotHaveBean(SpanExporters.class);
 		});
 	}
 
@@ -151,6 +157,8 @@ class OpenTelemetryAutoConfigurationTests {
 			assertThat(context).hasSingleBean(SpanCustomizer.class);
 			assertThat(context).hasBean("customSpanProcessors");
 			assertThat(context).hasSingleBean(SpanProcessors.class);
+			assertThat(context).hasBean("customSpanExporters");
+			assertThat(context).hasSingleBean(SpanExporters.class);
 		});
 	}
 
@@ -164,6 +172,17 @@ class OpenTelemetryAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void shouldAllowMultipleSpanExporters() {
+		this.contextRunner.withUserConfiguration(MultipleSpanExporterConfiguration.class).run((context) -> {
+			assertThat(context.getBeansOfType(SpanExporter.class)).hasSize(2);
+			assertThat(context).hasBean("spanExporter1");
+			assertThat(context).hasBean("spanExporter2");
+			SpanExporters spanExporters = context.getBean(SpanExporters.class);
+			assertThat(spanExporters).hasSize(2);
+		});
+	}
+
 	@Test
 	void shouldAllowMultipleTextMapPropagators() {
 		this.contextRunner.withUserConfiguration(CustomConfiguration.class).run((context) -> {
@@ -228,15 +247,6 @@ class OpenTelemetryAutoConfigurationTests {
 		});
 	}
 
-	private List<TextMapPropagator> getInjectors(TextMapPropagator propagator) {
-		assertThat(propagator).as("propagator").isNotNull();
-		if (propagator instanceof CompositeTextMapPropagator compositePropagator) {
-			return compositePropagator.getInjectors().stream().toList();
-		}
-		fail("Expected CompositeTextMapPropagator, found %s".formatted(propagator.getClass()));
-		throw new AssertionError("Unreachable");
-	}
-
 	@Test
 	void shouldCustomizeSdkTracerProvider() {
 		this.contextRunner.withUserConfiguration(SdkTracerProviderCustomizationConfiguration.class).run((context) -> {
@@ -255,6 +265,15 @@ class OpenTelemetryAutoConfigurationTests {
 		});
 	}
 
+	private List<TextMapPropagator> getInjectors(TextMapPropagator propagator) {
+		assertThat(propagator).as("propagator").isNotNull();
+		if (propagator instanceof CompositeTextMapPropagator compositePropagator) {
+			return compositePropagator.getInjectors().stream().toList();
+		}
+		fail("Expected CompositeTextMapPropagator, found %s".formatted(propagator.getClass()));
+		throw new AssertionError("Unreachable");
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	private static class MeterProviderConfiguration {
 
@@ -278,6 +297,21 @@ class OpenTelemetryAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	private static class MultipleSpanExporterConfiguration {
+
+		@Bean
+		SpanExporter spanExporter1() {
+			return new DummySpanExporter();
+		}
+
+		@Bean
+		SpanExporter spanExporter2() {
+			return new DummySpanExporter();
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	private static class CustomConfiguration {
 
@@ -286,6 +320,11 @@ class OpenTelemetryAutoConfigurationTests {
 			return SpanProcessors.of(mock(SpanProcessor.class));
 		}
 
+		@Bean
+		SpanExporters customSpanExporters() {
+			return SpanExporters.of(new DummySpanExporter());
+		}
+
 		@Bean
 		io.micrometer.tracing.Tracer customMicrometerTracer() {
 			return mock(io.micrometer.tracing.Tracer.class);
@@ -381,4 +420,23 @@ class OpenTelemetryAutoConfigurationTests {
 
 	}
 
+	private static class DummySpanExporter implements SpanExporter {
+
+		@Override
+		public CompletableResultCode export(Collection<SpanData> spans) {
+			return CompletableResultCode.ofSuccess();
+		}
+
+		@Override
+		public CompletableResultCode flush() {
+			return CompletableResultCode.ofSuccess();
+		}
+
+		@Override
+		public CompletableResultCode shutdown() {
+			return CompletableResultCode.ofSuccess();
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/tracing/SpanExportersTests.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2012-2023 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
+ *
+ *      https://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.boot.actuate.autoconfigure.tracing;
+
+import java.util.List;
+
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link SpanExporters}.
+ *
+ * @author Moritz Halbritter
+ */
+class SpanExportersTests {
+
+	@Test
+	void ofList() {
+		SpanExporter spanExporter1 = mock(SpanExporter.class);
+		SpanExporter spanExporter2 = mock(SpanExporter.class);
+		SpanExporters spanExporters = SpanExporters.of(List.of(spanExporter1, spanExporter2));
+		assertThat(spanExporters).containsExactly(spanExporter1, spanExporter2);
+		assertThat(spanExporters.getList()).containsExactly(spanExporter1, spanExporter2);
+	}
+
+	@Test
+	void ofArray() {
+		SpanExporter spanExporter1 = mock(SpanExporter.class);
+		SpanExporter spanExporter2 = mock(SpanExporter.class);
+		SpanExporters spanExporters = SpanExporters.of(spanExporter1, spanExporter2);
+		assertThat(spanExporters).containsExactly(spanExporter1, spanExporter2);
+		assertThat(spanExporters.getList()).containsExactly(spanExporter1, spanExporter2);
+	}
+
+}