Add an option to disable automatic kafka interceptor configuration in spring starter

Author: laurit

instrumentation/spring/spring-boot-autoconfigure/src/main/java/io/opentelemetry/instrumentation/spring/autoconfigure/internal/instrumentation/kafka/ConcurrentKafkaListenerContainerFactoryPostProcessor.java

@@ -5,43 +5,55 @@
 
 package io.opentelemetry.instrumentation.spring.autoconfigure.internal.instrumentation.kafka;
 
-import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.instrumentation.spring.kafka.v2_7.SpringKafkaTelemetry;
-import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
-import org.springframework.beans.factory.ObjectProvider;
+import java.lang.reflect.Field;
+import java.util.function.Supplier;
 import org.springframework.beans.factory.config.BeanPostProcessor;
+import org.springframework.kafka.config.AbstractKafkaListenerContainerFactory;
 import org.springframework.kafka.config.ConcurrentKafkaListenerContainerFactory;
+import org.springframework.kafka.listener.BatchInterceptor;
+import org.springframework.kafka.listener.RecordInterceptor;
 
 class ConcurrentKafkaListenerContainerFactoryPostProcessor implements BeanPostProcessor {
 
-  private final ObjectProvider<OpenTelemetry> openTelemetryProvider;
-  private final ObjectProvider<ConfigProperties> configPropertiesProvider;
+  private final Supplier<SpringKafkaTelemetry> springKafkaTelemetry;
 
   ConcurrentKafkaListenerContainerFactoryPostProcessor(
-      ObjectProvider<OpenTelemetry> openTelemetryProvider,
-      ObjectProvider<ConfigProperties> configPropertiesProvider) {
-    this.openTelemetryProvider = openTelemetryProvider;
-    this.configPropertiesProvider = configPropertiesProvider;
+      Supplier<SpringKafkaTelemetry> springKafkaTelemetry) {
+    this.springKafkaTelemetry = springKafkaTelemetry;
   }
 
+  @SuppressWarnings("unchecked")
   @Override
   public Object postProcessAfterInitialization(Object bean, String beanName) {
     if (!(bean instanceof ConcurrentKafkaListenerContainerFactory)) {
       return bean;
     }
 
-    ConcurrentKafkaListenerContainerFactory<?, ?> listenerContainerFactory =
-        (ConcurrentKafkaListenerContainerFactory<?, ?>) bean;
-    SpringKafkaTelemetry springKafkaTelemetry =
-        SpringKafkaTelemetry.builder(openTelemetryProvider.getObject())
-            .setCaptureExperimentalSpanAttributes(
-                configPropertiesProvider
-                    .getObject()
-                    .getBoolean("otel.instrumentation.kafka.experimental-span-attributes", false))
-            .build();
-    listenerContainerFactory.setBatchInterceptor(springKafkaTelemetry.createBatchInterceptor());
-    listenerContainerFactory.setRecordInterceptor(springKafkaTelemetry.createRecordInterceptor());
+    ConcurrentKafkaListenerContainerFactory<Object, Object> listenerContainerFactory =
+        (ConcurrentKafkaListenerContainerFactory<Object, Object>) bean;
+    SpringKafkaTelemetry springKafkaTelemetry = this.springKafkaTelemetry.get();
+
+    // use reflection to read existing values to avoid overwriting user configured interceptors
+    BatchInterceptor<Object, Object> batchInterceptor =
+        readField(listenerContainerFactory, "batchInterceptor", BatchInterceptor.class);
+    RecordInterceptor<Object, Object> recordInterceptor =
+        readField(listenerContainerFactory, "recordInterceptor", RecordInterceptor.class);
+    listenerContainerFactory.setBatchInterceptor(
+        springKafkaTelemetry.createBatchInterceptor(batchInterceptor));
+    listenerContainerFactory.setRecordInterceptor(
+        springKafkaTelemetry.createRecordInterceptor(recordInterceptor));
 
     return listenerContainerFactory;
   }
+
+  private static <T> T readField(Object container, String filedName, Class<T> fieldType) {
+    try {
+      Field field = AbstractKafkaListenerContainerFactory.class.getDeclaredField(filedName);
+      field.setAccessible(true);
+      return fieldType.cast(field.get(container));
+    } catch (Exception exception) {
+      return null;
+    }
+  }
 }

instrumentation/spring/spring-boot-autoconfigure/src/main/java/io/opentelemetry/instrumentation/spring/autoconfigure/internal/instrumentation/kafka/KafkaInstrumentationAutoConfiguration.java

@@ -8,9 +8,11 @@
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.instrumentation.kafkaclients.v2_6.KafkaTelemetry;
 import io.opentelemetry.instrumentation.spring.autoconfigure.internal.ConditionalOnEnabledInstrumentation;
+import io.opentelemetry.instrumentation.spring.kafka.v2_7.SpringKafkaTelemetry;
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.kafka.DefaultKafkaProducerFactoryCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -33,13 +35,29 @@ DefaultKafkaProducerFactoryCustomizer otelKafkaProducerFactoryCustomizer(
     return producerFactory -> producerFactory.addPostProcessor(kafkaTelemetry::wrap);
   }
 
+  @Bean
+  static SpringKafkaTelemetry getTelemetry(
+      ObjectProvider<OpenTelemetry> openTelemetryProvider,
+      ObjectProvider<ConfigProperties> configPropertiesProvider) {
+    return SpringKafkaTelemetry.builder(openTelemetryProvider.getObject())
+        .setCaptureExperimentalSpanAttributes(
+            configPropertiesProvider
+                .getObject()
+                .getBoolean("otel.instrumentation.kafka.experimental-span-attributes", false))
+        .build();
+  }
+
   // static to avoid "is not eligible for getting processed by all BeanPostProcessors" warning
   @Bean
+  @ConditionalOnProperty(
+      name = "otel.instrumentation.kafka.autoconfigure-interceptor",
+      havingValue = "true",
+      matchIfMissing = true)
   static ConcurrentKafkaListenerContainerFactoryPostProcessor
       otelKafkaListenerContainerFactoryBeanPostProcessor(
           ObjectProvider<OpenTelemetry> openTelemetryProvider,
           ObjectProvider<ConfigProperties> configPropertiesProvider) {
     return new ConcurrentKafkaListenerContainerFactoryPostProcessor(
-        openTelemetryProvider, configPropertiesProvider);
+        () -> getTelemetry(openTelemetryProvider, configPropertiesProvider));
   }
 }

instrumentation/spring/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -357,6 +357,12 @@
       "description": "Enable the capture of experimental Kafka span attributes.",
       "defaultValue": false
     },
+    {
+      "name": "otel.instrumentation.kafka.autoconfigure-interceptor",
+      "type": "java.lang.Boolean",
+      "description": "Enable automatic configuration of tracing interceptors on <code>ConcurrentKafkaListenerContainerFactory</code> using a <code>BeanPostProcessor</code>. You may disable this if you wish to manually configure these interceptors.",
+      "defaultValue": true
+    },
     {
       "name": "otel.instrumentation.mongo.enabled",
       "type": "java.lang.Boolean",