Merge pull request #44655 from nosan

* pr/44655:
  Polish "Introduce properties for configuring the OpenTelemetry BatchSpanProcessor"
  Introduce properties for configuring the OpenTelemetry BatchSpanProcessor

Closes gh-44655

Author: mhalbritter

Diff for: spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/OpenTelemetryTracingAutoConfiguration.java

@@ -119,9 +119,16 @@ SpanProcessors spanProcessors(ObjectProvider<SpanProcessor> spanProcessors) {
 	BatchSpanProcessor otelSpanProcessor(SpanExporters spanExporters,
 			ObjectProvider<SpanExportingPredicate> spanExportingPredicates, ObjectProvider<SpanReporter> spanReporters,
 			ObjectProvider<SpanFilter> spanFilters, ObjectProvider<MeterProvider> meterProvider) {
-		BatchSpanProcessorBuilder builder = BatchSpanProcessor
-			.builder(new CompositeSpanExporter(spanExporters.list(), spanExportingPredicates.orderedStream().toList(),
-					spanReporters.orderedStream().toList(), spanFilters.orderedStream().toList()));
+		TracingProperties.OpenTelemetry.Export properties = this.tracingProperties.getOpentelemetry().getExport();
+		CompositeSpanExporter spanExporter = new CompositeSpanExporter(spanExporters.list(),
+				spanExportingPredicates.orderedStream().toList(), spanReporters.orderedStream().toList(),
+				spanFilters.orderedStream().toList());
+		BatchSpanProcessorBuilder builder = BatchSpanProcessor.builder(spanExporter)
+			.setExportUnsampledSpans(properties.isIncludeUnsampled())
+			.setExporterTimeout(properties.getTimeout())
+			.setMaxExportBatchSize(properties.getMaxBatchSize())
+			.setMaxQueueSize(properties.getMaxQueueSize())
+			.setScheduleDelay(properties.getScheduleDelay());
 		meterProvider.ifAvailable(builder::setMeterProvider);
 		return builder.build();
 	}

Diff for: spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/TracingProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.boot.actuate.autoconfigure.tracing;
 
+import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -51,6 +52,11 @@ public class TracingProperties {
 	 */
 	private final Brave brave = new Brave();
 
+	/**
+	 * OpenTelemetry configuration.
+	 */
+	private final OpenTelemetry opentelemetry = new OpenTelemetry();
+
 	public Sampling getSampling() {
 		return this.sampling;
 	}
@@ -67,6 +73,10 @@ public Brave getBrave() {
 		return this.brave;
 	}
 
+	public OpenTelemetry getOpentelemetry() {
+		return this.opentelemetry;
+	}
+
 	public static class Sampling {
 
 		/**
@@ -293,4 +303,88 @@ public void setSpanJoiningSupported(boolean spanJoiningSupported) {
 
 	}
 
+	public static class OpenTelemetry {
+
+		/**
+		 * Span export configuration.
+		 */
+		private final Export export = new Export();
+
+		public Export getExport() {
+			return this.export;
+		}
+
+		public static class Export {
+
+			/**
+			 * Whether unsampled spans should be exported.
+			 */
+			private boolean includeUnsampled;
+
+			/**
+			 * Maximum time an export will be allowed to run before being cancelled.
+			 */
+			private Duration timeout = Duration.ofSeconds(30);
+
+			/**
+			 * Maximum batch size for each export. This must be less than or equal to
+			 * 'maxQueueSize'.
+			 */
+			private int maxBatchSize = 512;
+
+			/**
+			 * Maximum number of spans that are kept in the queue before they will be
+			 * dropped.
+			 */
+			private int maxQueueSize = 2048;
+
+			/**
+			 * The delay interval between two consecutive exports.
+			 */
+			private Duration scheduleDelay = Duration.ofSeconds(5);
+
+			public boolean isIncludeUnsampled() {
+				return this.includeUnsampled;
+			}
+
+			public void setIncludeUnsampled(boolean includeUnsampled) {
+				this.includeUnsampled = includeUnsampled;
+			}
+
+			public Duration getTimeout() {
+				return this.timeout;
+			}
+
+			public void setTimeout(Duration timeout) {
+				this.timeout = timeout;
+			}
+
+			public int getMaxBatchSize() {
+				return this.maxBatchSize;
+			}
+
+			public void setMaxBatchSize(int maxBatchSize) {
+				this.maxBatchSize = maxBatchSize;
+			}
+
+			public int getMaxQueueSize() {
+				return this.maxQueueSize;
+			}
+
+			public void setMaxQueueSize(int maxQueueSize) {
+				this.maxQueueSize = maxQueueSize;
+			}
+
+			public Duration getScheduleDelay() {
+				return this.scheduleDelay;
+			}
+
+			public void setScheduleDelay(Duration scheduleDelay) {
+				this.scheduleDelay = scheduleDelay;
+			}
+
+		}
+
+	}
+
 }

Diff for: spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/tracing/OpenTelemetryTracingAutoConfigurationTests.java

@@ -70,6 +70,7 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.annotation.Order;
+import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.fail;
@@ -324,6 +325,44 @@ void shouldDisablePropagationIfTracingIsDisabled() {
 		});
 	}
 
+	@Test
+	void batchSpanProcessorShouldBeConfiguredWithCustomProperties() {
+		this.contextRunner
+			.withPropertyValues("management.tracing.opentelemetry.export.timeout=45s",
+					"management.tracing.opentelemetry.export.include-unsampled=true",
+					"management.tracing.opentelemetry.export.max-batch-size=256",
+					"management.tracing.opentelemetry.export.max-queue-size=4096",
+					"management.tracing.opentelemetry.export.schedule-delay=15s")
+			.run((context) -> {
+				assertThat(context).hasSingleBean(BatchSpanProcessor.class);
+				BatchSpanProcessor batchSpanProcessor = context.getBean(BatchSpanProcessor.class);
+				assertThat(batchSpanProcessor).hasFieldOrPropertyWithValue("exportUnsampledSpans", true)
+					.extracting("worker")
+					.hasFieldOrPropertyWithValue("exporterTimeoutNanos", Duration.ofSeconds(45).toNanos())
+					.hasFieldOrPropertyWithValue("maxExportBatchSize", 256)
+					.hasFieldOrPropertyWithValue("scheduleDelayNanos", Duration.ofSeconds(15).toNanos())
+					.extracting("queue")
+					.satisfies((queue) -> assertThat(ReflectionTestUtils.<Integer>invokeMethod(queue, "capacity"))
+						.isEqualTo(4096));
+			});
+	}
+
+	@Test
+	void batchSpanProcessorShouldBeConfiguredWithDefaultProperties() {
+		this.contextRunner.run((context) -> {
+			assertThat(context).hasSingleBean(BatchSpanProcessor.class);
+			BatchSpanProcessor batchSpanProcessor = context.getBean(BatchSpanProcessor.class);
+			assertThat(batchSpanProcessor).hasFieldOrPropertyWithValue("exportUnsampledSpans", false)
+				.extracting("worker")
+				.hasFieldOrPropertyWithValue("exporterTimeoutNanos", Duration.ofSeconds(30).toNanos())
+				.hasFieldOrPropertyWithValue("maxExportBatchSize", 512)
+				.hasFieldOrPropertyWithValue("scheduleDelayNanos", Duration.ofSeconds(5).toNanos())
+				.extracting("queue")
+				.satisfies((queue) -> assertThat(ReflectionTestUtils.<Integer>invokeMethod(queue, "capacity"))
+					.isEqualTo(2048));
+		});
+	}
+
 	@Test // gh-41439
 	@ForkedClassPath
 	void shouldPublishEventsWhenContextStorageIsInitializedEarly() {