BAEL-5680: Guide to Check if Apache Kafka Server is Running (#12600)

Co-authored-by: Tapan Avasthi <tavasthi@Tapans-MacBook-Air.local>

apache-kafka-2/src/main/java/com/baeldung/kafka/KafkaAdminClient.java

@@ -0,0 +1,35 @@
+package com.baeldung.kafka;
+
+import java.util.Collection;
+import java.util.Properties;
+import java.util.concurrent.ExecutionException;
+
+import org.apache.kafka.clients.admin.AdminClient;
+import org.apache.kafka.common.Node;
+
+public class KafkaAdminClient {
+    private final AdminClient client;
+
+    public KafkaAdminClient(String bootstrap) {
+        Properties props = new Properties();
+        props.put("bootstrap.servers", bootstrap);
+        props.put("request.timeout.ms", 3000);
+        props.put("connections.max.idle.ms", 5000);
+
+        this.client = AdminClient.create(props);
+    }
+
+    public boolean verifyConnection() throws ExecutionException, InterruptedException {
+        Collection<Node> nodes = this.client.describeCluster()
+            .nodes()
+            .get();
+        return nodes != null && nodes.size() > 0;
+    }
+
+    public static void main(String[] args) throws ExecutionException, InterruptedException {
+        String defaultBootStrapServer = "localhost:9092";
+        KafkaAdminClient kafkaAdminClient = new KafkaAdminClient(defaultBootStrapServer);
+        System.out.println(kafkaAdminClient.verifyConnection());
+    }
+
+}

apache-kafka-2/src/test/java/com/baeldung/kafka/KafkaConnectionLiveTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.kafka;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+// This live test needs a running Docker instance so that a kafka container can be created
+
+@Testcontainers
+class KafkaConnectionLiveTest {
+
+    @Container
+    private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:5.4.3"));
+    private KafkaAdminClient kafkaAdminClient;
+
+    @BeforeEach
+    void setup() {
+        KAFKA_CONTAINER.addExposedPort(9092);
+        this.kafkaAdminClient = new KafkaAdminClient(KAFKA_CONTAINER.getBootstrapServers());
+    }
+
+    @AfterEach
+    void destroy() {
+        KAFKA_CONTAINER.stop();
+    }
+
+    @Test
+    void givenKafkaIsRunning_whenCheckedForConnection_thenConnectionIsVerified() throws Exception {
+        boolean alive = kafkaAdminClient.verifyConnection();
+        assertThat(alive).isTrue();
+    }
+
+}