Use spring.application.name for OTel service.name when not set

Closes gh-37285

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/otlp/OtlpMetricsExportAutoConfiguration.java

@@ -32,6 +32,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
+import org.springframework.core.env.Environment;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for exporting metrics to OTLP.
@@ -49,20 +50,11 @@ import org.springframework.context.annotation.Bean;
 @EnableConfigurationProperties({ OtlpProperties.class, OpenTelemetryProperties.class })
 public class OtlpMetricsExportAutoConfiguration {
 
-	private final OtlpProperties properties;
-
-	private final OpenTelemetryProperties openTelemetryProperties;
-
-	public OtlpMetricsExportAutoConfiguration(OtlpProperties properties,
-			OpenTelemetryProperties openTelemetryProperties) {
-		this.properties = properties;
-		this.openTelemetryProperties = openTelemetryProperties;
-	}
-
 	@Bean
 	@ConditionalOnMissingBean
-	public OtlpConfig otlpConfig() {
-		return new OtlpPropertiesConfigAdapter(this.properties, this.openTelemetryProperties);
+	OtlpConfig otlpConfig(OtlpProperties properties, OpenTelemetryProperties openTelemetryProperties,
+			Environment environment) {
+		return new OtlpPropertiesConfigAdapter(properties, openTelemetryProperties, environment);
 	}
 
 	@Bean

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/otlp/OtlpPropertiesConfigAdapter.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.actuate.autoconfigure.metrics.export.otlp;
 
+import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
@@ -24,6 +26,7 @@ import io.micrometer.registry.otlp.OtlpConfig;
 
 import org.springframework.boot.actuate.autoconfigure.metrics.export.properties.StepRegistryPropertiesConfigAdapter;
 import org.springframework.boot.actuate.autoconfigure.opentelemetry.OpenTelemetryProperties;
+import org.springframework.core.env.Environment;
 import org.springframework.util.CollectionUtils;
 
 /**
@@ -35,11 +38,20 @@ import org.springframework.util.CollectionUtils;
  */
 class OtlpPropertiesConfigAdapter extends StepRegistryPropertiesConfigAdapter<OtlpProperties> implements OtlpConfig {
 
+	/**
+	 * Default value for application name if {@code spring.application.name} is not set.
+	 */
+	private static final String DEFAULT_APPLICATION_NAME = "application";
+
 	private final OpenTelemetryProperties openTelemetryProperties;
 
-	OtlpPropertiesConfigAdapter(OtlpProperties properties, OpenTelemetryProperties openTelemetryProperties) {
+	private final Environment environment;
+
+	OtlpPropertiesConfigAdapter(OtlpProperties properties, OpenTelemetryProperties openTelemetryProperties,
+			Environment environment) {
 		super(properties);
 		this.openTelemetryProperties = openTelemetryProperties;
+		this.environment = environment;
 	}
 
 	@Override
@@ -60,10 +72,16 @@ class OtlpPropertiesConfigAdapter extends StepRegistryPropertiesConfigAdapter<Ot
 	@Override
 	@SuppressWarnings("removal")
 	public Map<String, String> resourceAttributes() {
+		Map<String, String> result;
 		if (!CollectionUtils.isEmpty(this.openTelemetryProperties.getResourceAttributes())) {
-			return this.openTelemetryProperties.getResourceAttributes();
+			result = new HashMap<>(this.openTelemetryProperties.getResourceAttributes());
 		}
-		return get(OtlpProperties::getResourceAttributes, OtlpConfig.super::resourceAttributes);
+		else {
+			result = new HashMap<>(get(OtlpProperties::getResourceAttributes, OtlpConfig.super::resourceAttributes));
+		}
+		result.computeIfAbsent("service.name",
+				(ignore) -> this.environment.getProperty("spring.application.name", DEFAULT_APPLICATION_NAME));
+		return Collections.unmodifiableMap(result);
 	}
 
 	@Override

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/export/otlp/OtlpPropertiesConfigAdapterTests.java

@@ -25,6 +25,7 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.actuate.autoconfigure.opentelemetry.OpenTelemetryProperties;
+import org.springframework.mock.env.MockEnvironment;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.entry;
@@ -41,10 +42,13 @@ class OtlpPropertiesConfigAdapterTests {
 
 	private OpenTelemetryProperties openTelemetryProperties;
 
+	private MockEnvironment environment;
+
 	@BeforeEach
 	void setUp() {
 		this.properties = new OtlpProperties();
 		this.openTelemetryProperties = new OpenTelemetryProperties();
+		this.environment = new MockEnvironment();
 	}
 
 	@Test
@@ -93,7 +97,8 @@ class OtlpPropertiesConfigAdapterTests {
 	void openTelemetryPropertiesShouldOverrideOtlpPropertiesIfNotEmpty() {
 		this.properties.setResourceAttributes(Map.of("a", "alpha"));
 		this.openTelemetryProperties.setResourceAttributes(Map.of("b", "beta"));
-		assertThat(createAdapter().resourceAttributes()).containsExactly(entry("b", "beta"));
+		assertThat(createAdapter().resourceAttributes()).contains(entry("b", "beta"));
+		assertThat(createAdapter().resourceAttributes()).doesNotContain(entry("a", "alpha"));
 	}
 
 	@Test
@@ -101,11 +106,37 @@ class OtlpPropertiesConfigAdapterTests {
 	void openTelemetryPropertiesShouldNotOverrideOtlpPropertiesIfEmpty() {
 		this.properties.setResourceAttributes(Map.of("a", "alpha"));
 		this.openTelemetryProperties.setResourceAttributes(Collections.emptyMap());
-		assertThat(createAdapter().resourceAttributes()).containsExactly(entry("a", "alpha"));
+		assertThat(createAdapter().resourceAttributes()).contains(entry("a", "alpha"));
+	}
+
+	@Test
+	@SuppressWarnings("removal")
+	void serviceNameOverridesApplicationName() {
+		this.environment.setProperty("spring.application.name", "alpha");
+		this.properties.setResourceAttributes(Map.of("service.name", "beta"));
+		assertThat(createAdapter().resourceAttributes()).containsEntry("service.name", "beta");
+	}
+
+	@Test
+	void serviceNameOverridesApplicationNameWhenUsingOtelProperties() {
+		this.environment.setProperty("spring.application.name", "alpha");
+		this.openTelemetryProperties.setResourceAttributes(Map.of("service.name", "beta"));
+		assertThat(createAdapter().resourceAttributes()).containsEntry("service.name", "beta");
+	}
+
+	@Test
+	void shouldUseApplicationNameIfServiceNameIsNotSet() {
+		this.environment.setProperty("spring.application.name", "alpha");
+		assertThat(createAdapter().resourceAttributes()).containsEntry("service.name", "alpha");
+	}
+
+	@Test
+	void shouldUseDefaultApplicationNameIfApplicationNameIsNotSet() {
+		assertThat(createAdapter().resourceAttributes()).containsEntry("service.name", "application");
 	}
 
 	private OtlpPropertiesConfigAdapter createAdapter() {
-		return new OtlpPropertiesConfigAdapter(this.properties, this.openTelemetryProperties);
+		return new OtlpPropertiesConfigAdapter(this.properties, this.openTelemetryProperties, this.environment);
 	}
 
 }