Polish "Add auto-configuration for OTLP span exporter"

See gh-34508

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

@@ -22,6 +22,7 @@
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.exporter.otlp.http.trace.OtlpHttpSpanExporter;
 import io.opentelemetry.exporter.otlp.http.trace.OtlpHttpSpanExporterBuilder;
+import io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter;
 import io.opentelemetry.sdk.trace.SdkTracerProvider;
 
 import org.springframework.boot.actuate.autoconfigure.tracing.ConditionalOnEnabledTracing;
@@ -41,7 +42,7 @@
  * "https://github.com/open-telemetry/opentelemetry-java/issues/3651">opentelemetry-java#3651</a>.
  * Because this class configures components from the OTel SDK, it can't support HTTP/JSON.
  * To keep things simple, we only auto-configure HTTP/protobuf. If you want to use gRPC,
- * please disable this auto-configuration and create a bean.
+ * define an {@link OtlpGrpcSpanExporter} and this auto-configuration will back off.
  *
  * @author Jonatan Ivanov
  * @since 3.1.0
@@ -53,19 +54,17 @@
 public class OtlpAutoConfiguration {
 
 	@Bean
-	@ConditionalOnMissingBean
+	@ConditionalOnMissingBean(value = OtlpHttpSpanExporter.class,
+			type = "io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter")
 	OtlpHttpSpanExporter otlpHttpSpanExporter(OtlpProperties properties) {
 		OtlpHttpSpanExporterBuilder builder = OtlpHttpSpanExporter.builder()
 			.setEndpoint(properties.getEndpoint())
 			.setTimeout(properties.getTimeout())
 			.setCompression(properties.getCompression().name().toLowerCase());
-
 		for (Entry<String, String> header : properties.getHeaders().entrySet()) {
 			builder.addHeader(header.getKey(), header.getValue());
 		}
-
 		return builder.build();
-
 	}
 
 }

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

@@ -23,7 +23,7 @@
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 /**
- * Configuration properties for {@link OtlpAutoConfiguration}.
+ * Configuration properties for exporting traces using OTLP.
  *
  * @author Jonatan Ivanov
  * @since 3.1.0

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

@@ -54,11 +54,10 @@ class OtlpAutoConfigurationIntegrationTests {
 				AutoConfigurations.of(ObservationAutoConfiguration.class, MicrometerTracingAutoConfiguration.class,
 						OpenTelemetryAutoConfiguration.class, OtlpAutoConfiguration.class));
 
-	private MockWebServer mockWebServer;
+	private final MockWebServer mockWebServer = new MockWebServer();
 
 	@BeforeEach
 	void setUp() throws IOException {
-		this.mockWebServer = new MockWebServer();
 		this.mockWebServer.start();
 	}
 
@@ -68,7 +67,7 @@ void tearDown() throws IOException {
 	}
 
 	@Test
-	void httpSpanExporterShouldUseProtoBufAndNoCompression() {
+	void httpSpanExporterShouldUseProtoBufAndNoCompressionByDefault() {
 		this.mockWebServer.enqueue(new MockResponse());
 		this.contextRunner
 			.withPropertyValues("management.otlp.tracing.endpoint=http://localhost:%d/v1/traces"
@@ -77,7 +76,6 @@ void httpSpanExporterShouldUseProtoBufAndNoCompression() {
 				context.getBean(Tracer.class).nextSpan().name("test").end();
 				assertThat(context.getBean(OtlpHttpSpanExporter.class).flush())
 					.isSameAs(CompletableResultCode.ofSuccess());
-
 				RecordedRequest request = this.mockWebServer.takeRequest(10, TimeUnit.SECONDS);
 				assertThat(request).isNotNull();
 				assertThat(request.getRequestLine()).contains("/v1/traces");
@@ -91,17 +89,16 @@ void httpSpanExporterShouldUseProtoBufAndNoCompression() {
 	}
 
 	@Test
-	void httpSpanExporterShouldUseProtoBufAndGzip() {
+	void httpSpanExporterCanBeConfiguredToUseGzipCompression() {
 		this.mockWebServer.enqueue(new MockResponse());
 		this.contextRunner
-			.withPropertyValues("management.otlp.tracing.compression=GZIP",
+			.withPropertyValues("management.otlp.tracing.compression=gzip",
 					"management.otlp.tracing.endpoint=http://localhost:%d/test".formatted(this.mockWebServer.getPort()))
 			.run((context) -> {
 				assertThat(context).hasSingleBean(OtlpHttpSpanExporter.class).hasSingleBean(SpanExporter.class);
 				context.getBean(Tracer.class).nextSpan().name("test").end();
 				assertThat(context.getBean(OtlpHttpSpanExporter.class).flush())
 					.isSameAs(CompletableResultCode.ofSuccess());
-
 				RecordedRequest request = this.mockWebServer.takeRequest(10, TimeUnit.SECONDS);
 				assertThat(request).isNotNull();
 				assertThat(request.getRequestLine()).contains("/test");

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

@@ -76,16 +76,15 @@ void shouldNotSupplyBeansIfExporterIsMissing() {
 	}
 
 	@Test
-	void shouldSupplyCustomHttpExporter() {
+	void shouldBackOffWhenCustomHttpExporterIsDefined() {
 		this.contextRunner.withUserConfiguration(CustomHttpExporterConfiguration.class)
 			.run((context) -> assertThat(context).hasBean("customOtlpHttpSpanExporter")
 				.hasSingleBean(SpanExporter.class));
 	}
 
 	@Test
-	void shouldSupplyCustomGrpcExporter() {
-		this.contextRunner.withClassLoader(new FilteredClassLoader("io.opentelemetry.exporter"))
-			.withUserConfiguration(CustomGrpcExporterConfiguration.class)
+	void shouldBackOffWhenCustomGrpcExporterIsDefined() {
+		this.contextRunner.withUserConfiguration(CustomGrpcExporterConfiguration.class)
 			.run((context) -> assertThat(context).hasBean("customOtlpGrpcSpanExporter")
 				.hasSingleBean(SpanExporter.class));
 	}