Add auto-configuration for OTLP span exporter

With these changes an OTLP exporter is auto-configured
if opentelemetry-exporter-otlp is on the classpath.
By default HTTP is used but gRPC is also available.

Closes gh-34390

spring-boot-project/spring-boot-actuator-autoconfigure/build.gradle

@@ -70,6 +70,7 @@ dependencies {
 	optional("io.micrometer:micrometer-registry-wavefront")
 	optional("io.zipkin.reporter2:zipkin-sender-urlconnection")
 	optional("io.opentelemetry:opentelemetry-exporter-zipkin")
+	optional("io.opentelemetry:opentelemetry-exporter-otlp")
 	optional("io.projectreactor.netty:reactor-netty-http")
 	optional("io.r2dbc:r2dbc-pool")
 	optional("io.r2dbc:r2dbc-spi")

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

@@ -0,0 +1,88 @@
+/*
+ * 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.otlp;
+
+import io.micrometer.tracing.otel.bridge.OtelTracer;
+import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.exporter.otlp.http.trace.OtlpHttpSpanExporter;
+import io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter;
+import io.opentelemetry.sdk.trace.SdkTracerProvider;
+
+import org.springframework.boot.actuate.autoconfigure.tracing.ConditionalOnEnabledTracing;
+import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * {@link EnableAutoConfiguration Auto-configuration} for OTLP. Brave does not support
+ * OTLP, so we only configure it for OpenTelemetry. OTLP defines three transports that are
+ * supported: gRPC (/protobuf), HTTP/protobuf, HTTP/JSON. From these transports HTTP/JSON
+ * is not supported by the OTel Java SDK, and it seems there are no plans supporting it in
+ * the future, see: <a href=
+ * "https://github.com/open-telemetry/opentelemetry-java/issues/3651">opentelemetry-java#3651</a>.
+ * Because this class configures components from the OTel SDK, it can only support what
+ * the OTel SDK does: gRPC and HTTP/protobuf.
+ *
+ * @author Jonatan Ivanov
+ * @since 3.1.0
+ */
+@AutoConfiguration
+@ConditionalOnEnabledTracing
+@ConditionalOnClass({ OtelTracer.class, SdkTracerProvider.class, OpenTelemetry.class })
+@EnableConfigurationProperties(OtlpProperties.class)
+public class OtlpAutoConfiguration {
+
+	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnClass(OtlpHttpSpanExporter.class)
+	@ConditionalOnProperty(prefix = "management.otlp.tracing.http", name = "enabled", matchIfMissing = true)
+	static class HttpConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean
+		OtlpHttpSpanExporter otlpHttpSpanExporter(OtlpProperties properties) {
+			return OtlpHttpSpanExporter.builder()
+				.setEndpoint(properties.getHttp().getEndpoint())
+				.setTimeout(properties.getHttp().getTimeout())
+				.setCompression(properties.getHttp().getCompression().name().toLowerCase())
+				.build();
+		}
+
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnClass(OtlpGrpcSpanExporter.class)
+	@ConditionalOnProperty(prefix = "management.otlp.tracing.grpc", name = "enabled")
+	static class GrpcConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean
+		OtlpGrpcSpanExporter otlpGrpcSpanExporter(OtlpProperties properties) {
+			return OtlpGrpcSpanExporter.builder()
+				.setEndpoint(properties.getGrpc().getEndpoint())
+				.setTimeout(properties.getGrpc().getTimeout())
+				.setCompression(properties.getGrpc().getCompression().name().toLowerCase())
+				.build();
+		}
+
+	}
+
+}

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

@@ -0,0 +1,182 @@
+/*
+ * 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.otlp;
+
+import java.time.Duration;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+/**
+ * Configuration properties for {@link OtlpAutoConfiguration}.
+ *
+ * @author Jonatan Ivanov
+ * @since 3.1.0
+ */
+@ConfigurationProperties("management.otlp.tracing")
+public class OtlpProperties {
+
+	/**
+	 * HTTP configuration.
+	 */
+	private final Http http = new Http();
+
+	/**
+	 * gRPC configuration.
+	 */
+	private final Grpc grpc = new Grpc();
+
+	public Http getHttp() {
+		return this.http;
+	}
+
+	public Grpc getGrpc() {
+		return this.grpc;
+	}
+
+	public static class Http {
+
+		/**
+		 * Whether auto-configuration of HTTP exporter is enabled.
+		 */
+		private boolean enabled = true;
+
+		/**
+		 * URL to the OTel collector's HTTP API.
+		 */
+		private String endpoint = "http://localhost:4318/v1/traces";
+
+		/**
+		 * Call timeout for the OTel Collector to process an exported batch of data. This
+		 * timeout spans the entire call: resolving DNS, connecting, writing the request
+		 * body, server processing, and reading the response body. If the call requires
+		 * redirects or retries all must complete within one timeout period.
+		 */
+		private Duration timeout = Duration.ofSeconds(10);
+
+		/**
+		 * The method used to compress the payload.
+		 */
+		private Compression compression = Compression.NONE;
+
+		public boolean isEnabled() {
+			return this.enabled;
+		}
+
+		public void setEnabled(boolean enabled) {
+			this.enabled = enabled;
+		}
+
+		public String getEndpoint() {
+			return this.endpoint;
+		}
+
+		public void setEndpoint(String endpoint) {
+			this.endpoint = endpoint;
+		}
+
+		public Duration getTimeout() {
+			return this.timeout;
+		}
+
+		public void setTimeout(Duration timeout) {
+			this.timeout = timeout;
+		}
+
+		public Compression getCompression() {
+			return this.compression;
+		}
+
+		public void setCompression(Compression compression) {
+			this.compression = compression;
+		}
+
+	}
+
+	public static class Grpc {
+
+		/**
+		 * Whether auto-configuration of gRPC exporter is enabled.
+		 */
+		private boolean enabled = false;
+
+		/**
+		 * URL to the OTel collector's gRPC API.
+		 */
+		private String endpoint = "http://localhost:4317";
+
+		/**
+		 * Call timeout for the OTel Collector to process an exported batch of data. This
+		 * timeout spans the entire call: resolving DNS, connecting, writing the request
+		 * body, server processing, and reading the response body. If the call requires
+		 * redirects or retries all must complete within one timeout period.
+		 */
+		private Duration timeout = Duration.ofSeconds(10);
+
+		/**
+		 * The method used to compress the payload.
+		 */
+		private Compression compression = Compression.NONE;
+
+		public boolean isEnabled() {
+			return this.enabled;
+		}
+
+		public void setEnabled(boolean enabled) {
+			this.enabled = enabled;
+		}
+
+		public String getEndpoint() {
+			return this.endpoint;
+		}
+
+		public void setEndpoint(String endpoint) {
+			this.endpoint = endpoint;
+		}
+
+		public Duration getTimeout() {
+			return this.timeout;
+		}
+
+		public void setTimeout(Duration timeout) {
+			this.timeout = timeout;
+		}
+
+		public Compression getCompression() {
+			return this.compression;
+		}
+
+		public void setCompression(Compression compression) {
+			this.compression = compression;
+		}
+
+	}
+
+	enum Compression {
+
+		/**
+		 * Gzip compression.
+		 */
+		GZIP,
+
+		/**
+		 * No compression.
+		 */
+		NONE
+
+	}
+
+}

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

@@ -0,0 +1,20 @@
+/*
+ * 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.
+ */
+
+/**
+ * Auto-configuration for tracing with OTLP.
+ */
+package org.springframework.boot.actuate.autoconfigure.tracing.otlp;

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -100,6 +100,7 @@ org.springframework.boot.actuate.autoconfigure.system.DiskSpaceHealthContributor
 org.springframework.boot.actuate.autoconfigure.tracing.BraveAutoConfiguration
 org.springframework.boot.actuate.autoconfigure.tracing.MicrometerTracingAutoConfiguration
 org.springframework.boot.actuate.autoconfigure.tracing.OpenTelemetryAutoConfiguration
+org.springframework.boot.actuate.autoconfigure.tracing.otlp.OtlpAutoConfiguration
 org.springframework.boot.actuate.autoconfigure.tracing.prometheus.PrometheusExemplarsAutoConfiguration
 org.springframework.boot.actuate.autoconfigure.tracing.wavefront.WavefrontTracingAutoConfiguration
 org.springframework.boot.actuate.autoconfigure.tracing.zipkin.ZipkinAutoConfiguration