Add local-datacenter property for Cassandra

The Cassandra v4 driver does not longer have automatic local DC inference
from contact points. As a result, the "local-datacenter" property must be
set with the default load balancing policy and the contact points must
be of that data center.

This commit adds a new property for the local datacenter so that it can
be specified without the use of a customizer.

Closes gh-19779

Author: snicoll

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraAutoConfiguration.java

@@ -114,6 +114,8 @@ private Config cassandraConfiguration(CassandraProperties properties) {
 		mapPoolingOptions(properties, options);
 		map.from(properties::getContactPoints)
 				.to((contactPoints) -> options.add(DefaultDriverOption.CONTACT_POINTS, contactPoints));
+		map.from(properties.getLocalDatacenter()).to(
+				(localDatacenter) -> options.add(DefaultDriverOption.LOAD_BALANCING_LOCAL_DATACENTER, localDatacenter));
 		ConfigFactory.invalidateCaches();
 		return ConfigFactory.defaultOverrides().withFallback(options.build())
 				.withFallback(ConfigFactory.defaultReference()).resolve();

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraProperties.java

@@ -55,6 +55,12 @@ public class CassandraProperties {
 	 */
 	private final List<String> contactPoints = new ArrayList<>(Collections.singleton("127.0.0.1:9042"));
 
+	/**
+	 * Datacenter that is considered "local". Contact points should be from this
+	 * datacenter.
+	 */
+	private String localDatacenter;
+
 	/**
 	 * Login user of the server.
 	 */
@@ -141,6 +147,14 @@ public List<String> getContactPoints() {
 		return this.contactPoints;
 	}
 
+	public String getLocalDatacenter() {
+		return this.localDatacenter;
+	}
+
+	public void setLocalDatacenter(String localDatacenter) {
+		this.localDatacenter = localDatacenter;
+	}
+
 	public String getUsername() {
 		return this.username;
 	}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/cassandra/CassandraAutoConfigurationTests.java

@@ -51,6 +51,20 @@ void driverConfigLoaderWithDefaultConfiguration() {
 		});
 	}
 
+	@Test
+	void driverConfigLoaderWithContactPoints() {
+		this.contextRunner.withPropertyValues("spring.data.cassandra.contact-points=cluster.example.com:9042",
+				"spring.data.cassandra.local-datacenter=cassandra-eu1").run((context) -> {
+					assertThat(context).hasSingleBean(DriverConfigLoader.class);
+					DriverExecutionProfile configuration = context.getBean(DriverConfigLoader.class).getInitialConfig()
+							.getDefaultProfile();
+					assertThat(configuration.getStringList(DefaultDriverOption.CONTACT_POINTS))
+							.containsOnly("cluster.example.com:9042");
+					assertThat(configuration.getString(DefaultDriverOption.LOAD_BALANCING_LOCAL_DATACENTER))
+							.isEqualTo("cassandra-eu1");
+				});
+	}
+
 	@Test
 	void driverConfigLoaderWithCustomSessionName() {
 		this.contextRunner.withPropertyValues("spring.data.cassandra.session-name=testcluster").run((context) -> {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/cassandra/CassandraDataAutoConfigurationIntegrationTests.java

@@ -29,12 +29,9 @@
 
 import org.springframework.boot.autoconfigure.AutoConfigurationPackages;
 import org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration;
-import org.springframework.boot.autoconfigure.cassandra.CqlSessionBuilderCustomizer;
 import org.springframework.boot.autoconfigure.data.cassandra.city.City;
 import org.springframework.boot.test.util.TestPropertyValues;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
 import org.springframework.data.cassandra.config.SchemaAction;
 import org.springframework.data.cassandra.config.SessionFactoryFactoryBean;
 
@@ -58,9 +55,9 @@ class CassandraDataAutoConfigurationIntegrationTests {
 	@BeforeEach
 	void setUp() {
 		this.context = new AnnotationConfigApplicationContext();
-		this.context.register(TestConfiguration.class);
 		TestPropertyValues
 				.of("spring.data.cassandra.contact-points:localhost:" + cassandra.getFirstMappedPort(),
+						"spring.data.cassandra.local-datacenter=datacenter1",
 						"spring.data.cassandra.read-timeout=24000", "spring.data.cassandra.connect-timeout=10000")
 				.applyTo(this.context.getEnvironment());
 	}
@@ -105,14 +102,4 @@ private void createTestKeyspaceIfNotExists() {
 		}
 	}
 
-	@Configuration
-	static class TestConfiguration {
-
-		@Bean
-		CqlSessionBuilderCustomizer sessionCustomizer() {
-			return (builder) -> builder.withLocalDatacenter("datacenter1");
-		}
-
-	}
-
 }