eugenp · jzheaux · May 22, 2025 · Apr 12, 2025 · Apr 13, 2025 · Apr 13, 2025
diff --git a/spring-kafka-4/pom.xml b/spring-kafka-4/pom.xml
@@ -27,6 +27,10 @@
             <groupId>org.springframework.kafka</groupId>
             <artifactId>spring-kafka</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-actuator</artifactId>
+        </dependency>
 
         <!-- test dependencies -->
         <dependency>

diff --git a/spring-kafka-4/src/main/java/com/baeldung/kafka/monitoring/ArticleCommentAddedEvent.java b/spring-kafka-4/src/main/java/com/baeldung/kafka/monitoring/ArticleCommentAddedEvent.java
@@ -0,0 +1,5 @@
+package com.baeldung.kafka.monitoring;
+
+public record ArticleCommentAddedEvent(String articleSlug, String articleAuthor, String comment, String commentAuthor) {
+
+}
diff --git a/spring-kafka-4/src/main/java/com/baeldung/kafka/monitoring/ArticleCommentsListener.java b/spring-kafka-4/src/main/java/com/baeldung/kafka/monitoring/ArticleCommentsListener.java
@@ -0,0 +1,23 @@
+package com.baeldung.kafka.monitoring;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.kafka.annotation.KafkaListener;
+import org.springframework.messaging.handler.annotation.Header;
+import org.springframework.stereotype.Component;
+
+@Component
+public class ArticleCommentsListener {
+
+    private static final Logger log = LoggerFactory.getLogger(ArticleCommentsRestController.class);
+
+    @KafkaListener(
+        topics = "baeldung.article-comment.added",
+        containerFactory = "customKafkaListenerContainerFactory"
+    )
+    public void onArticleComment(ArticleCommentAddedEvent event, @Header("traceparent") String traceParent) {
+        log.info("Kafka Message Received: Comment Added: " + event);
+        // some logic here...
+    }
+
+}
diff --git a/...ng-kafka-4/src/main/java/com/baeldung/kafka/monitoring/ArticleCommentsRestController.java b/...ng-kafka-4/src/main/java/com/baeldung/kafka/monitoring/ArticleCommentsRestController.java
@@ -0,0 +1,48 @@
+package com.baeldung.kafka.monitoring;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.kafka.core.KafkaTemplate;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/api")
+public class ArticleCommentsRestController {
+
+    private static final Logger log = LoggerFactory.getLogger(ArticleCommentsRestController.class);
+
+    private final KafkaTemplate<String, ArticleCommentAddedEvent> articleCommentsKafkaTemplate;
+
+    public ArticleCommentsRestController(
+        @Qualifier("articleCommentsKafkaTemplate") KafkaTemplate<String, ArticleCommentAddedEvent> articleCommentsKafkaTemplate) {
+        this.articleCommentsKafkaTemplate = articleCommentsKafkaTemplate;
+    }
+
+    @PostMapping("/articles/{articleSlug}/comments")
+    Response addArticleComment(
+        @PathVariable("articleSlug") String articleSlug,
+        @RequestBody ArticleCommentAddedDto dto
+    ) {
+
+        log.info("HTTP Request received to save article comment: " + dto);
+        // some logic here (eg: save to DB)
+
+        var event = new ArticleCommentAddedEvent(articleSlug, dto.articleAuthor(), dto.comment(), dto.commentAuthor());
+        articleCommentsKafkaTemplate.send("baeldung.article-comment.added", articleSlug, event);
+
+        return new Response("Success", articleSlug);
+    }
+
+    record Response(String status, String articleSlug) {
+
+    }
+
+    record ArticleCommentAddedDto(String articleAuthor, String comment, String commentAuthor) {
+
+    }
+}
diff --git a/spring-kafka-4/src/main/java/com/baeldung/kafka/monitoring/KafkaConfig.java b/spring-kafka-4/src/main/java/com/baeldung/kafka/monitoring/KafkaConfig.java
@@ -0,0 +1,69 @@
+package com.baeldung.kafka.monitoring;
+
+import static java.util.Collections.singletonList;
+
+import java.util.Map;
+
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.boot.autoconfigure.kafka.KafkaProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.kafka.config.ConcurrentKafkaListenerContainerFactory;
+import org.springframework.kafka.core.ConsumerFactory;
+import org.springframework.kafka.core.DefaultKafkaConsumerFactory;
+import org.springframework.kafka.core.DefaultKafkaProducerFactory;
+import org.springframework.kafka.core.KafkaTemplate;
+import org.springframework.kafka.core.MicrometerConsumerListener;
+import org.springframework.kafka.core.MicrometerProducerListener;
+import org.springframework.kafka.core.ProducerFactory;
+import org.springframework.kafka.listener.ContainerProperties;
+
+import io.micrometer.core.instrument.ImmutableTag;
+import io.micrometer.core.instrument.MeterRegistry;
+
+@Configuration
+class KafkaConfig {
+
+    @Bean
+    ConsumerFactory<String, String> consumerFactory(KafkaProperties kafkaProperties, MeterRegistry meterRegistry) {
+        DefaultKafkaConsumerFactory<String, String> cf = new DefaultKafkaConsumerFactory<>(kafkaProperties.buildConsumerProperties());
+        cf.addListener(new MicrometerConsumerListener<>(meterRegistry, singletonList(new ImmutableTag("app-name", "article-comments-app"))));
+        return cf;
+    }
+
+    @Bean
+    ProducerFactory<String, ArticleCommentAddedEvent> producerFactory(KafkaProperties kafkaProperties, MeterRegistry meterRegistry) {
+        ProducerFactory<String, ArticleCommentAddedEvent> pf = new DefaultKafkaProducerFactory<>(kafkaProperties.buildProducerProperties());
+        pf.addListener(new MicrometerProducerListener<>(meterRegistry, singletonList(new ImmutableTag("app-name", "article-comments-app"))));
+        return pf;
+    }
+
+    @Bean
+    @Qualifier("articleCommentsKafkaTemplate")
+    KafkaTemplate<String, ArticleCommentAddedEvent> articleCommentsKafkaTemplate(ProducerFactory<String, ArticleCommentAddedEvent> producerFactory) {
+        var template = new KafkaTemplate<>(producerFactory);
+
+        template.setObservationEnabled(true);
+        template.setMicrometerTags(Map.of("topic", "baeldung.article-comment.added"));
+        template.setMicrometerTagsProvider(record -> Map.of("article-slug", record.key()
+            .toString()));
+
+        return template;
+    }
+
+    @Bean
+    ConcurrentKafkaListenerContainerFactory<String, String> customKafkaListenerContainerFactory(ConsumerFactory<String, String> consumerFactory) {
+
+        ConcurrentKafkaListenerContainerFactory<String, String> factory = new ConcurrentKafkaListenerContainerFactory<>();
+        factory.setConsumerFactory(consumerFactory);
+
+        ContainerProperties containerProps = factory.getContainerProperties();
+        containerProps.setObservationEnabled(true);
+        containerProps.setMicrometerTags(Map.of("app-name", "article-comments-app"));
+        containerProps.setMicrometerTagsProvider(record -> Map.of("article-slug", record.key()
+            .toString()));
+
+        return factory;
+    }
+
+}
diff --git a/spring-kafka-4/src/main/java/com/baeldung/kafka/monitoring/KafkaMonitoringApplication.java b/spring-kafka-4/src/main/java/com/baeldung/kafka/monitoring/KafkaMonitoringApplication.java
@@ -0,0 +1,16 @@
+package com.baeldung.kafka.monitoring;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+
+@SpringBootApplication
+class KafkaMonitoringApplication {
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder()
+            .profiles("monitoring")
+            .sources(KafkaMonitoringApplication.class)
+            .run(args);
+    }
+
+}
diff --git a/spring-kafka-4/src/main/resources/application-monitoring.yml b/spring-kafka-4/src/main/resources/application-monitoring.yml
@@ -0,0 +1,22 @@
+
+management:
+  endpoints.web.exposure.include: '*'
+  endpoint.health.show-details: always
+
+spring:
+  application:
+    name: kafka-monitoring
+  kafka:
+    bootstrap-servers: localhost:9092
+    consumer:
+      group-id: baeldung-app-1
+      auto-offset-reset: earliest
+      key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
+      value-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
+      properties:
+        spring.json.value.default.type: com.baeldung.kafka.monitoring.ArticleCommentAddedEvent
+        spring.json.trusted.packages: com.baeldung.kafka.monitoring
+
+    producer:
+      key-serializer: org.apache.kafka.common.serialization.StringSerializer
+      value-serializer: org.springframework.kafka.support.serializer.JsonSerializer
diff --git a/spring-kafka-4/src/main/resources/application.properties b/spring-kafka-4/src/main/resources/application.properties
diff --git a/spring-kafka-4/src/main/resources/application.yml b/spring-kafka-4/src/main/resources/application.yml
@@ -0,0 +1,3 @@
+server.port: 8081
+spring.kafka.bootstrap-servers: localhost:9092
+long.message.topic.name: longMessage
diff --git a/spring-kafka-4/src/main/resources/logback.xml b/spring-kafka-4/src/main/resources/logback.xml
@@ -2,7 +2,7 @@
 <configuration>
     <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
         <encoder>
-            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %X{traceId:-}-%X{spanId:-} %-5level %logger{36} - %msg%n
             </pattern>
         </encoder>
     </appender>

diff --git a/spring-kafka-4/src/test/resources/post_article_comment.cmd b/spring-kafka-4/src/test/resources/post_article_comment.cmd
@@ -0,0 +1,3 @@
+curl --location "http://localhost:8081/api/articles/oop-best-practices/comments" ^
+--header "Content-Type: application/json" ^
+--data "{\"articleAuthor\": \"Andrey the Author\", \"comment\": \"Great article!\", \"commentAuthor\": \"Richard the Reader\"}"