DATACASS-798 - Introduce CassandraDriverOptionsConfigurer and allow specifying a configuration file.

We now allow configuring a DriverConfigLoaderBuilderConfigurer and specifying a driver configuration file through AbstractSessionConfiguration to improve configuration possibilities. The DriverConfigLoaderBuilderConfigurer gets applied after applying the configuration to DriverConfigLoaderBuilder. The driver config file acts as a fallback config if the configuration property cannot be looked up from system properties or from the configuration in DriverConfigLoaderBuilder.

spring-data-cassandra/src/main/java/org/springframework/data/cassandra/config/AbstractSessionConfiguration.java

@@ -15,6 +15,8 @@
  */
 package org.springframework.data.cassandra.config;
 
+import java.io.IOException;
+import java.io.InputStreamReader;
 import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -26,6 +28,7 @@ import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.io.Resource;
 import org.springframework.data.cassandra.SessionFactory;
 import org.springframework.data.cassandra.core.cql.CqlTemplate;
 import org.springframework.data.cassandra.core.cql.keyspace.CreateKeyspaceSpecification;
@@ -224,6 +227,33 @@ public abstract class AbstractSessionConfiguration implements BeanFactoryAware {
 		return null;
 	}
 
+	/**
+	 * Returns the {@link DriverConfigLoaderBuilderConfigurer}. The configuration gets applied after applying
+	 * {@link System#getProperties() System Properties} config overrides and before
+	 * {@link #getDriverConfigurationResource() the driver config file}.
+	 *
+	 * @return the {@link DriverConfigLoaderBuilderConfigurer}; may be {@literal null}.
+	 * @since 3.1.2
+	 */
+	@Nullable
+	protected DriverConfigLoaderBuilderConfigurer getDriverConfigLoaderBuilderConfigurer() {
+		return null;
+	}
+
+	/**
+	 * Returns the {@link Resource} pointing to a driver configuration file. The configuration file is applied after
+	 * applying {@link System#getProperties() System Properties} and the configuration built by this configuration class.
+	 *
+	 * @return the {@link Resource}; may be {@literal null} if none provided.
+	 * @since 3.1.2
+	 * @see <a href="https://docs.datastax.com/en/developer/java-driver/4.9/manual/core/configuration/">Driver
+	 *      Configuration</a>
+	 */
+	@Nullable
+	protected Resource getDriverConfigurationResource() {
+		return null;
+	}
+
 	/**
 	 * Returns the list of CQL scripts to be run on startup after {@link #getKeyspaceCreations() Keyspace creations}
 	 * and after initialization of the {@literal System} Keyspace.
@@ -280,7 +310,9 @@ public abstract class AbstractSessionConfiguration implements BeanFactoryAware {
 
 	private SessionBuilderConfigurer getSessionBuilderConfigurerWrapper() {
 
-		SessionBuilderConfigurer configurer = getSessionBuilderConfigurer();
+		SessionBuilderConfigurer sessionConfigurer = getSessionBuilderConfigurer();
+		DriverConfigLoaderBuilderConfigurer driverConfigLoaderConfigurer = getDriverConfigLoaderBuilderConfigurer();
+		Resource driverConfigFile = getDriverConfigurationResource();
 
 		return sessionBuilder -> {
 
@@ -302,16 +334,30 @@ public abstract class AbstractSessionConfiguration implements BeanFactoryAware {
 
 				ConfigFactory.invalidateCaches();
 
-				return ConfigFactory.defaultOverrides() //
-						.withFallback(options.build()) //
-						.withFallback(ConfigFactory.defaultReference());
+				Config config = ConfigFactory.defaultOverrides() //
+						.withFallback(options.build());
+
+				if (driverConfigFile != null) {
+					try {
+						config = config
+								.withFallback(ConfigFactory.parseReader(new InputStreamReader(driverConfigFile.getInputStream())));
+					} catch (IOException e) {
+						throw new IllegalStateException(String.format("Cannot parse driver config file %s", driverConfigFile), e);
+					}
+				}
+
+				return config.withFallback(ConfigFactory.defaultReference());
 
 			}, DefaultDriverConfigLoader.DEFAULT_ROOT_PATH);
 
+			if (driverConfigLoaderConfigurer != null) {
+				driverConfigLoaderConfigurer.configure(builder);
+			}
+
 			sessionBuilder.withConfigLoader(builder.build());
 
-			if (configurer != null) {
-				return configurer.configure(sessionBuilder);
+			if (sessionConfigurer != null) {
+				return sessionConfigurer.configure(sessionBuilder);
 			}
 
 			return sessionBuilder;

spring-data-cassandra/src/main/java/org/springframework/data/cassandra/config/DriverConfigLoaderBuilderConfigurer.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.cassandra.config;
+
+import com.datastax.oss.driver.api.core.config.ProgrammaticDriverConfigLoaderBuilder;
+
+/**
+ * Callback interface that can be implemented by beans wishing to customize the
+ * {@link ProgrammaticDriverConfigLoaderBuilder} via a {@link DriverConfigLoaderBuilderConfigurer} whilst retaining
+ * default configuration.
+ *
+ * @author Mark Paluch
+ * @since 3.1.2
+ */
+public interface DriverConfigLoaderBuilderConfigurer {
+
+	/**
+	 * Customize the {@linkplain ProgrammaticDriverConfigLoaderBuilder DriverConfigLoader builder}.
+	 *
+	 * @param builder the builder to customize
+	 */
+	void configure(ProgrammaticDriverConfigLoaderBuilder builder);
+
+}

spring-data-cassandra/src/test/java/org/springframework/data/cassandra/config/AbstractSessionConfigurationIntegrationTests.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.cassandra.config;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.Resource;
+import org.springframework.data.cassandra.support.CassandraConnectionProperties;
+import org.springframework.data.cassandra.test.util.CassandraExtension;
+import org.springframework.lang.Nullable;
+
+import com.datastax.oss.driver.api.core.CqlSession;
+import com.datastax.oss.driver.api.core.config.DefaultDriverOption;
+
+/**
+ * Unit tests for {@link AbstractSessionConfiguration}.
+ *
+ * @author Mark Paluch
+ */
+@ExtendWith(CassandraExtension.class)
+class AbstractSessionConfigurationIntegrationTests {
+
+	@Test
+	void shouldApplyDriverConfigLoaderBuilderConfigurer() {
+
+		MySessionConfiguration configuration = new MySessionConfiguration();
+		CqlSessionFactoryBean bean = configuration.cassandraSession();
+		bean.afterPropertiesSet();
+		CqlSession session = bean.getObject();
+
+		assertThat(session.getContext().getConfig().getProfile("foo")).isNotNull();
+		assertThat(session.getContext().getConfig().getProfiles()).doesNotContainKeys("bar");
+	}
+
+	@Test
+	void shouldApplyConfigurationFile() {
+
+		MySessionConfiguration configuration = new MySessionConfiguration();
+		CqlSessionFactoryBean bean = configuration.cassandraSession();
+		bean.afterPropertiesSet();
+		CqlSession session = bean.getObject();
+
+		assertThat(session.getContext().getConfig().getProfile("oltp")).isNotNull();
+		assertThat(session.getContext().getConfig().getProfiles()).doesNotContainKeys("bar");
+	}
+
+	static class MySessionConfiguration extends AbstractSessionConfiguration {
+
+		@Override
+		protected String getKeyspaceName() {
+			return "system";
+		}
+
+		@Nullable
+		@Override
+		protected String getLocalDataCenter() {
+			return "datacenter1";
+		}
+
+		@Override
+		protected int getPort() {
+			return new CassandraConnectionProperties().getCassandraPort();
+		}
+
+		@Nullable
+		@Override
+		protected DriverConfigLoaderBuilderConfigurer getDriverConfigLoaderBuilderConfigurer() {
+			return it -> {
+				it.startProfile("foo").withString(DefaultDriverOption.SESSION_NAME, "hello-world").endProfile();
+			};
+		}
+
+		@Nullable
+		@Override
+		protected Resource getDriverConfigurationResource() {
+			return new ClassPathResource("application.conf");
+		}
+	}
+
+}

spring-data-cassandra/src/test/resources/application.conf

@@ -11,6 +11,13 @@
 # This file is in HOCON format, see https://github.com/typesafehub/config/blob/master/HOCON.md.
 datastax-java-driver {
 
+  profiles {
+    oltp {
+      basic.request.timeout = 100 milliseconds
+      basic.request.consistency = ONE
+      }
+  }
+
   basic.load-balancing-policy {
     class = DcInferringLoadBalancingPolicy
   }