Detect the presence of autoconfig for Brave, fail the context initialization if it present and let the user know that they need to pics one tracer. (#38)

Author: jonatan-ivanov

docs/src/main/asciidoc/_configprops.adoc

@@ -17,6 +17,7 @@
 |spring.sleuth.otel.exporter.sleuth-span-filter.enabled | `true` | Enables Sleuth span filter.
 |spring.sleuth.otel.log.exporter.enabled | `false` | Enable log exporter for OTel.
 |spring.sleuth.otel.log.slf4j.enabled | `false` | Enable slf4j support for OTel.
+|spring.sleuth.otel.multiple-tracer-configs-detector-enabled | `true` | Enable detection of autoconfiguration for multiple tracers (i.e.: Brave and OTel); only one of them should be used.
 |spring.sleuth.otel.propagation.composite-text-map-propagator.enabled | `true` | Enable a composite text map propagator that can combine multiple propagation types into a single text map propagator.
 |spring.sleuth.otel.propagation.sleuth-baggage.enabled | `true` | Enable propagating baggage in a Sleuth compatible way (baggage key & value pair means e.g. a key & value HTTP pair).
 |spring.sleuth.otel.resource.enabled | `true` | Enables default {@link Resource} implementations.

spring-cloud-sleuth-otel-autoconfigure/pom.xml

@@ -321,6 +321,12 @@
 			<version>${grpc-netty-shaded.version}</version>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-sleuth-tests-otel-common</artifactId>
+			<version>${project.version}</version>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 
 	<profiles>

spring-cloud-sleuth-otel-autoconfigure/src/main/java/org/springframework/cloud/sleuth/autoconfig/otel/MultipleTracerAutoConfigurationsDetector.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2021-2021 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.cloud.sleuth.autoconfig.otel;
+
+import javax.annotation.PostConstruct;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Detects if both OTel (this project) and autoconfiguration for Brave are both on the
+ * classpath.
+ *
+ * @author Jonatan Ivanov
+ * @since 1.0.0
+ */
+@Configuration
+@ConditionalOnClass(name = "org.springframework.cloud.sleuth.autoconfig.brave.BraveAutoConfiguration")
+@ConditionalOnProperty(
+		value = { "spring.sleuth.enabled", "spring.sleuth.otel.multiple-tracer-configs-detector-enabled" },
+		matchIfMissing = true)
+class MultipleTracerAutoConfigurationsDetector {
+
+	@PostConstruct
+	void signalMultipleTracerAutoConfigurationsPresent() {
+		throw new MultipleTracersFoundException();
+	}
+
+	static final class MultipleTracersFoundException extends RuntimeException {
+
+		MultipleTracersFoundException() {
+			super("You have both Spring Cloud Sleuth OpenTelemetry (OTel) and Spring Cloud Sleuth Brave tracers on the "
+					+ "classpath. Please exclude <org.springframework.cloud:spring-cloud-sleuth-brave> dependency from "
+					+ "<org.springframework.cloud:spring-cloud-starter-sleuth>.");
+		}
+
+	}
+
+}

spring-cloud-sleuth-otel-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -1,5 +1,11 @@
 {
   "properties": [
+    {
+      "name": "spring.sleuth.otel.multiple-tracer-configs-detector-enabled",
+      "type": "java.lang.Boolean",
+      "description": "Enable detection of autoconfiguration for multiple tracers (i.e.: Brave and OTel); only one of them should be used.",
+      "defaultValue": true
+    },
     {
       "name": "spring.sleuth.otel.propagation.sleuth-baggage.enabled",
       "type": "java.lang.Boolean",

spring-cloud-sleuth-otel-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -1,6 +1,7 @@
 # Auto Configuration
 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
 org.springframework.cloud.sleuth.autoconfig.otel.OtelAutoConfiguration,\
+org.springframework.cloud.sleuth.autoconfig.otel.MultipleTracerAutoConfigurationsDetector,\
 org.springframework.cloud.sleuth.autoconfig.otel.instrument.opentracing.OtelOpentracingAutoConfiguration,\
 org.springframework.cloud.sleuth.autoconfig.otel.zipkin2.ZipkinOtelAutoConfiguration,\
 org.springframework.cloud.sleuth.autoconfig.otel.wavefront.WavefrontOtelAutoConfiguration

spring-cloud-sleuth-otel-autoconfigure/src/test/java/org/springframework/cloud/sleuth/autoconfig/otel/MultipleTracerAutoConfigurationsDetectorTest.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2021-2021 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.cloud.sleuth.autoconfig.otel;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.FilteredClassLoader;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class MultipleTracerAutoConfigurationsDetectorTest {
+
+	@Test
+	void should_fail_when_brave_and_otel_autoconfig_is_on_the_classpath() {
+		new ApplicationContextRunner()
+				.withConfiguration(AutoConfigurations.of(MultipleTracerAutoConfigurationsDetector.class))
+				.run(context -> assertThat(context.getStartupFailure()).hasRootCauseInstanceOf(
+						MultipleTracerAutoConfigurationsDetector.MultipleTracersFoundException.class));
+	}
+
+	@Test
+	void should_not_fail_when_brave_autoconfig_is_not_on_the_classpath() {
+		new ApplicationContextRunner()
+				.withClassLoader(new FilteredClassLoader(
+						"org.springframework.cloud.sleuth.autoconfig.brave.BraveAutoConfiguration"))
+				.withConfiguration(AutoConfigurations.of(MultipleTracerAutoConfigurationsDetector.class))
+				.run(context -> assertThat(context).hasNotFailed());
+	}
+
+	@Test
+	void should_not_fail_when_sleuth_is_disabled() {
+		new ApplicationContextRunner().withPropertyValues("spring.sleuth.enabled=false")
+				.withConfiguration(AutoConfigurations.of(MultipleTracerAutoConfigurationsDetector.class))
+				.run(context -> assertThat(context).hasNotFailed());
+	}
+
+	@Test
+	void should_not_fail_when_detector_is_disabled() {
+		new ApplicationContextRunner()
+				.withPropertyValues("spring.sleuth.otel.multiple-tracer-configs-detector-enabled=false")
+				.withConfiguration(AutoConfigurations.of(MultipleTracerAutoConfigurationsDetector.class))
+				.run(context -> assertThat(context).hasNotFailed());
+	}
+
+}

spring-cloud-sleuth-otel-autoconfigure/src/test/resources/META-INF/spring.factories

@@ -1,3 +1,6 @@
 # Auto Configuration
 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
-org.springframework.cloud.sleuth.autoconfig.TraceNoOpAutoConfiguration
+org.springframework.cloud.sleuth.autoconfig.TraceNoOpAutoConfiguration
+
+org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
+org.springframework.cloud.sleuth.autoconfig.otel.MultipleTracerAutoConfigurationsDetectorFilter

tests/common/pom.xml

@@ -59,7 +59,7 @@
 		</dependency>
 		<dependency>
 			<groupId>org.springframework.cloud</groupId>
-			<artifactId>spring-cloud-sleuth-otel-autoconfigure</artifactId>
+			<artifactId>spring-cloud-sleuth-otel</artifactId>
 		</dependency>
 		<dependency>
 			<groupId>io.opentelemetry</groupId>

tests/common/src/main/java/org/springframework/cloud/sleuth/autoconfig/otel/MultipleTracerAutoConfigurationsDetectorFilter.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2021-2021 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.cloud.sleuth.autoconfig.otel;
+
+import org.springframework.boot.autoconfigure.AutoConfigurationImportFilter;
+import org.springframework.boot.autoconfigure.AutoConfigurationMetadata;
+
+/**
+ * Filter that can be registered in {@code spring.factories} to exclude
+ * MultipleTracerAutoConfigurationsDetector. This can be handy in tests where there is no
+ * other way to disable the detector (e.g.: property or context runner).
+ *
+ * @author Jonatan Ivanov
+ */
+public class MultipleTracerAutoConfigurationsDetectorFilter implements AutoConfigurationImportFilter {
+
+	private static final String EXCLUDED = "org.springframework.cloud.sleuth.autoconfig.otel.MultipleTracerAutoConfigurationsDetector";
+
+	@Override
+	public boolean[] match(String[] autoConfigurationClasses, AutoConfigurationMetadata autoConfigurationMetadata) {
+		boolean[] matches = new boolean[autoConfigurationClasses.length];
+		for (int i = 0; i < autoConfigurationClasses.length; i++) {
+			matches[i] = isMatching(autoConfigurationClasses[i]);
+		}
+
+		return matches;
+	}
+
+	private boolean isMatching(String autoConfigurationClass) {
+		return !EXCLUDED.equals(autoConfigurationClass);
+	}
+
+}

tests/otel/spring-cloud-sleuth-instrumentation-annotation-tests/src/test/resources/application.yml

@@ -2,4 +2,6 @@ logging.level.org.springframework.cloud: DEBUG
 logging.level.com.netflix.discovery.InstanceInfoReplicator: ERROR
 logging.level.org.springframework.cloud.sleuth.brave.instrument.web.client.feign: TRACE
 
-spring.autoconfigure.exclude: org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration, org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration, org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration, org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration, org.springframework.cloud.gateway.config.GatewayAutoConfiguration, org.springframework.cloud.gateway.config.GatewayClassPathWarningAutoConfiguration, org.springframework.cloud.gateway.config.GatewayMetricsAutoConfiguration
+spring.sleuth.otel.multiple-tracer-configs-detector-enabled: false
+
+spring.autoconfigure.exclude: org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration, org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration, org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration, org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration, org.springframework.cloud.gateway.config.GatewayAutoConfiguration, org.springframework.cloud.gateway.config.GatewayClassPathWarningAutoConfiguration, org.springframework.cloud.gateway.config.GatewayMetricsAutoConfiguration