Add the kafka-basics module

kafka-basics/src/test/java/com/ankurm/kafkabasics/TestcontainersConfiguration.java

@@ -0,0 +1,45 @@
+package com.ankurm.kafkabasics;
+
+import org.springframework.boot.test.context.TestConfiguration;
+import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
+import org.springframework.context.annotation.Bean;
+import org.testcontainers.kafka.KafkaContainer;
+import org.testcontainers.utility.DockerImageName;
+
+/**
+ * The Testcontainers route. Import this instead of {@code @EmbeddedKafka} when you want the same
+ * broker image your production cluster runs, or when you are testing something the in-process
+ * broker does not model (real network partitions, TLS, SASL, quotas).
+ *
+ * <p>{@code @ServiceConnection} is what makes this ergonomic: it registers the container's
+ * bootstrap servers as the application's, so there is no
+ * {@code @DynamicPropertySource} block and no {@code spring.kafka.bootstrap-servers} to keep in
+ * sync. It replaced that boilerplate in Boot 3.1 and is the only shape worth writing now.
+ *
+ * <p>Two coordinates matter and both changed recently:
+ * <ul>
+ *   <li>the Maven artifact is <b>{@code org.testcontainers:testcontainers-kafka}</b>, not
+ *       {@code org.testcontainers:kafka}, which stopped at 1.21.4</li>
+ *   <li>the class is <b>{@code org.testcontainers.kafka.KafkaContainer}</b> (Apache Kafka,
+ *       KRaft, no ZooKeeper), not {@code org.testcontainers.containers.KafkaContainer}</li>
+ * </ul>
+ *
+ * <p>The transcripts under {@code docs/output/} were NOT produced by this class &mdash; they came
+ * from the in-process KRaft broker, because the machine that regenerates them has no Docker
+ * daemon. Both paths run the same tests.
+ *
+ * @see <a href="../../../../../docs/07-testing.md">docs/07-testing.md</a>
+ */
+@TestConfiguration(proxyBeanMethods = false)
+public class TestcontainersConfiguration {
+
+	// @RestartScope from spring-boot-devtools is worth adding here if you use `bootTestRun`:
+	// it keeps the container alive across devtools restarts. It needs the devtools dependency,
+	// which this module deliberately does not have.
+	@Bean
+	@ServiceConnection
+	KafkaContainer kafkaContainer() {
+		return new KafkaContainer(DockerImageName.parse("apache/kafka:4.1.0"));
+	}
+
+}