eugenp · davidmartinezbarua · Oct 18, 2024 · Aug 24, 2024 · Oct 9, 2024 · Oct 10, 2024
diff --git a/spring-kafka-4/pom.xml b/spring-kafka-4/pom.xml
@@ -19,11 +19,24 @@
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.springframework.kafka</groupId>
             <artifactId>spring-kafka</artifactId>
             <version>${spring-kafka.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-webflux</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.springframework.kafka</groupId>
             <artifactId>spring-kafka-test</artifactId>

diff --git a/spring-kafka-4/src/main/java/com/baeldung/seek/Application.java b/spring-kafka-4/src/main/java/com/baeldung/seek/Application.java
@@ -0,0 +1,13 @@
+package com.baeldung.seek;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+
+}
diff --git a/spring-kafka-4/src/main/java/com/baeldung/seek/ConsumerListener.java b/spring-kafka-4/src/main/java/com/baeldung/seek/ConsumerListener.java
@@ -0,0 +1,27 @@
+package com.baeldung.seek;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.common.TopicPartition;
+import org.springframework.kafka.annotation.KafkaListener;
+import org.springframework.kafka.listener.AbstractConsumerSeekAware;
+import org.springframework.stereotype.Component;
+
+@Component
+class ConsumerListener extends AbstractConsumerSeekAware {
+
+    public static final Map<String, String> MESSAGES = new HashMap<>();
+
+    @Override
+    public void onPartitionsAssigned(Map<TopicPartition, Long> assignments, ConsumerSeekCallback callback) {
+        assignments.keySet()
+            .forEach(tp -> callback.seekRelative(tp.topic(), tp.partition(), -1, false));
+    }
+
+    @KafkaListener(id = "test-seek", topics = "test-seek-topic")
+    public void listen(ConsumerRecord<String, String> in) {
+        MESSAGES.put(in.key(), in.value());
+    }
+}
diff --git a/spring-kafka-4/src/main/java/com/baeldung/seek/Response.java b/spring-kafka-4/src/main/java/com/baeldung/seek/Response.java
@@ -0,0 +1,5 @@
+package com.baeldung.seek;
+
+public record Response(int partition, long offset, String value) {
+
+}
diff --git a/spring-kafka-4/src/main/java/com/baeldung/seek/SeekController.java b/spring-kafka-4/src/main/java/com/baeldung/seek/SeekController.java
@@ -0,0 +1,75 @@
+package com.baeldung.seek;
+
+import java.time.Duration;
+import java.util.Collections;
+import java.util.Iterator;
+
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.TopicPartition;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.kafka.core.DefaultKafkaConsumerFactory;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/seek/api/v1/")
+public class SeekController {
+
+    public static final String TOPIC_NAME = "test-topic";
+
+    private final DefaultKafkaConsumerFactory<String, String> consumerFactory;
+
+    public SeekController(DefaultKafkaConsumerFactory<String, String> consumerFactory) {
+        this.consumerFactory = consumerFactory;
+    }
+
+    @GetMapping("partition/{partition}/offset/{offset}")
+    public ResponseEntity<Response> getOneByPartitionAndOffset(@PathVariable("partition") int partition, @PathVariable("offset") int offset) {
+        try (KafkaConsumer<String, String> consumer = (KafkaConsumer<String, String>) consumerFactory.createConsumer()) {
+            TopicPartition topicPartition = new TopicPartition(TOPIC_NAME, partition);
+            consumer.assign(Collections.singletonList(topicPartition));
+            consumer.seek(topicPartition, offset);
+            ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
+            Iterator<ConsumerRecord<String, String>> recordIterator = records.iterator();
+            if (recordIterator.hasNext()) {
+                ConsumerRecord<String, String> consumerRecord = recordIterator.next();
+                Response response = new Response(consumerRecord.partition(), consumerRecord.offset(), consumerRecord.value());
+                return new ResponseEntity<>(response, HttpStatus.OK);
+            }
+        }
+        return new ResponseEntity<>(HttpStatus.NOT_FOUND);
+    }
+
+    @GetMapping("partition/{partition}/beginning")
+    public ResponseEntity<Response> getOneByPartitionToBeginningOffset(@PathVariable("partition") int partition) {
+        try (KafkaConsumer<String, String> consumer = (KafkaConsumer<String, String>) consumerFactory.createConsumer()) {
+            TopicPartition topicPartition = new TopicPartition(TOPIC_NAME, partition);
+            consumer.assign(Collections.singletonList(topicPartition));
+            consumer.seekToBeginning(Collections.singleton(topicPartition));
+            ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
+            Iterator<ConsumerRecord<String, String>> recordIterator = records.iterator();
+            if (recordIterator.hasNext()) {
+                ConsumerRecord<String, String> consumerRecord = recordIterator.next();
+                Response response = new Response(consumerRecord.partition(), consumerRecord.offset(), consumerRecord.value());
+                return new ResponseEntity<>(response, HttpStatus.OK);
+            }
+        }
+        return new ResponseEntity<>(HttpStatus.NOT_FOUND);
+    }
+
+    @GetMapping("partition/{partition}/end")
+    public ResponseEntity<Long> getOneByPartitionToEndOffset(@PathVariable("partition") int partition) {
+        try (KafkaConsumer<String, String> consumer = (KafkaConsumer<String, String>) consumerFactory.createConsumer()) {
+            TopicPartition topicPartition = new TopicPartition(TOPIC_NAME, partition);
+            consumer.assign(Collections.singletonList(topicPartition));
+            consumer.seekToEnd(Collections.singleton(topicPartition));
+            return new ResponseEntity<>(consumer.position(topicPartition), HttpStatus.OK);
+        }
+    }
+
+}
diff --git a/spring-kafka-4/src/test/java/com/baeldung/seek/ConsumerListenerSeekLiveTest.java b/spring-kafka-4/src/test/java/com/baeldung/seek/ConsumerListenerSeekLiveTest.java
@@ -0,0 +1,72 @@
+package com.baeldung.seek;
+
+import java.util.Map;
+import java.util.Properties;
+import java.util.concurrent.ExecutionException;
+import java.util.stream.IntStream;
+
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.DynamicPropertyRegistry;
+import org.springframework.test.context.DynamicPropertySource;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.read.ListAppender;
+
+@Testcontainers
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+class ConsumerListenerSeekLiveTest {
+
+    protected static ListAppender<ILoggingEvent> listAppender;
+
+    @Autowired
+    ConsumerListener consumerListener;
+
+    @Container
+    private static KafkaContainer KAFKA = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
+    private static KafkaProducer<String, String> testKafkaProducer;
+
+    @DynamicPropertySource
+    static void setProps(DynamicPropertyRegistry registry) {
+        registry.add("spring.kafka.bootstrap-servers", KAFKA::getBootstrapServers);
+    }
+
+    @BeforeAll
+    static void beforeAll() {
+        Properties props = new Properties();
+        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA.getBootstrapServers());
+        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        testKafkaProducer = new KafkaProducer<>(props);
+        IntStream.range(0, 5)
+            .forEach(m -> {
+                ProducerRecord<String, String> record = new ProducerRecord<>("test-seek-topic", 0, String.valueOf(m), "Message no : %s".formatted(m));
+                try {
+                    testKafkaProducer.send(record)
+                        .get();
+                } catch (InterruptedException | ExecutionException e) {
+                    throw new RuntimeException(e);
+                }
+            });
+        testKafkaProducer.flush();
+    }
+
+    @Test
+    void givenKafkaBrokerExists_whenMessagesAreSent_thenLastMessageShouldBeRetrieved() {
+        Map<String, String> messages = consumerListener.MESSAGES;
+        Assertions.assertEquals(1, messages.size());
+        Assertions.assertEquals("Message no : 4", messages.get("4"));
+    }
+
+}
diff --git a/spring-kafka-4/src/test/java/com/baeldung/seek/SeekControllerLiveTest.java b/spring-kafka-4/src/test/java/com/baeldung/seek/SeekControllerLiveTest.java
@@ -0,0 +1,99 @@
+package com.baeldung.seek;
+
+import static com.baeldung.seek.SeekController.TOPIC_NAME;
+
+import java.util.Properties;
+import java.util.Random;
+import java.util.concurrent.ExecutionException;
+import java.util.stream.IntStream;
+
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.DynamicPropertyRegistry;
+import org.springframework.test.context.DynamicPropertySource;
+import org.springframework.test.web.reactive.server.WebTestClient;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+@Testcontainers
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+@AutoConfigureWebTestClient
+class SeekControllerLiveTest {
+
+    @Autowired
+    private WebTestClient webClient;
+
+    @Container
+    private static KafkaContainer KAFKA = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
+    private static KafkaProducer<String, String> testKafkaProducer;
+
+    @DynamicPropertySource
+    static void setProps(DynamicPropertyRegistry registry) {
+        registry.add("spring.kafka.bootstrap-servers", KAFKA::getBootstrapServers);
+    }
+
+    @BeforeAll
+    static void beforeAll() {
+        Properties props = new Properties();
+        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA.getBootstrapServers());
+        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        testKafkaProducer = new KafkaProducer<>(props);
+        int partition = 0;
+        IntStream.range(0, 5)
+            .forEach(m -> {
+                String key = String.valueOf(new Random().nextInt());
+                String value = "Message no : %s".formatted(m);
+                ProducerRecord<String, String> record = new ProducerRecord<>(TOPIC_NAME, partition, key, value);
+                try {
+                    testKafkaProducer.send(record)
+                        .get();
+                } catch (InterruptedException | ExecutionException e) {
+                    throw new RuntimeException(e);
+                }
+            });
+    }
+
+    @Test
+    void givenKafkaBrokerExists_whenSeekByPartitionAndOffset_thenMessageShouldBeRetrieved() {
+        this.webClient.get()
+            .uri("/seek/api/v1/partition/0/offset/2")
+            .exchange()
+            .expectStatus()
+            .isOk()
+            .expectBody(String.class)
+            .isEqualTo("{\"partition\":0,\"offset\":2,\"value\":\"Message no : 2\"}");
+    }
+
+    @Test
+    void givenKafkaBrokerExists_whenSeekByBeginning_thenFirstMessageShouldBeRetrieved() {
+        this.webClient.get()
+            .uri("/seek/api/v1/partition/0/beginning")
+            .exchange()
+            .expectStatus()
+            .isOk()
+            .expectBody(String.class)
+            .isEqualTo("{\"partition\":0,\"offset\":0,\"value\":\"Message no : 0\"}");
+    }
+
+    @Test
+    void givenKafkaBrokerExists_whenSeekByEnd_thenLatestOffsetShouldBeRetrieved() {
+        this.webClient.get()
+            .uri("/seek/api/v1/partition/0/end")
+            .exchange()
+            .expectStatus()
+            .isOk()
+            .expectBody(Long.class)
+            .isEqualTo(5L);
+    }
+
+}