Add support for configuring a Batch-specific DataSource

See gh-17375

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/batch/BatchAutoConfiguration.java

@@ -76,8 +76,10 @@ public class BatchAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean
 	@ConditionalOnBean(DataSource.class)
-	public BatchDataSourceInitializer batchDataSourceInitializer(DataSource dataSource, ResourceLoader resourceLoader) {
+	public BatchDataSourceInitializer batchDataSourceInitializer(ObjectProvider<DataSource> dataSource,
-		return new BatchDataSourceInitializer(dataSource, resourceLoader, this.properties);
+			@BatchDataSource ObjectProvider<DataSource> batchDataSource, ResourceLoader resourceLoader) {
+		return new BatchDataSourceInitializer(batchDataSource.getIfAvailable(dataSource::getIfAvailable),
+				resourceLoader, this.properties);
 	}
 
 	@Bean

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/batch/BatchConfigurerConfiguration.java

@@ -36,6 +36,7 @@ import org.springframework.transaction.PlatformTransactionManager;
  */
 @ConditionalOnClass(PlatformTransactionManager.class)
 @ConditionalOnMissingBean(BatchConfigurer.class)
+@ConditionalOnBean(DataSource.class)
 @Configuration(proxyBeanMethods = false)
 class BatchConfigurerConfiguration {
 
@@ -44,9 +45,11 @@ class BatchConfigurerConfiguration {
 	static class JdbcBatchConfiguration {
 
 		@Bean
-		BasicBatchConfigurer batchConfigurer(BatchProperties properties, DataSource dataSource,
+		BasicBatchConfigurer batchConfigurer(BatchProperties properties, ObjectProvider<DataSource> dataSource,
+				@BatchDataSource ObjectProvider<DataSource> batchDataSource,
 				ObjectProvider<TransactionManagerCustomizers> transactionManagerCustomizers) {
-			return new BasicBatchConfigurer(properties, dataSource, transactionManagerCustomizers.getIfAvailable());
+			return new BasicBatchConfigurer(properties, batchDataSource.getIfAvailable(dataSource::getIfAvailable),
+					transactionManagerCustomizers.getIfAvailable());
 		}
 
 	}
@@ -57,11 +60,12 @@ class BatchConfigurerConfiguration {
 	static class JpaBatchConfiguration {
 
 		@Bean
-		JpaBatchConfigurer batchConfigurer(BatchProperties properties, DataSource dataSource,
+		JpaBatchConfigurer batchConfigurer(BatchProperties properties, ObjectProvider<DataSource> dataSource,
+				@BatchDataSource ObjectProvider<DataSource> batchDataSource,
 				ObjectProvider<TransactionManagerCustomizers> transactionManagerCustomizers,
 				EntityManagerFactory entityManagerFactory) {
-			return new JpaBatchConfigurer(properties, dataSource, transactionManagerCustomizers.getIfAvailable(),
+			return new JpaBatchConfigurer(properties, batchDataSource.getIfAvailable(dataSource::getIfAvailable),
-					entityManagerFactory);
+					transactionManagerCustomizers.getIfAvailable(), entityManagerFactory);
 		}
 
 	}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/batch/BatchDataSource.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2012-2019 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.boot.autoconfigure.batch;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.beans.factory.annotation.Qualifier;
+
+/**
+ * Qualifier annotation to allow a Batch-specific DataSource.
+ *
+ * @author Dmytro Nosan
+ * @since 2.2.0
+ */
+@Target({ ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.TYPE, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Qualifier
+public @interface BatchDataSource {
+
+}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/batch/BatchAutoConfigurationTests.java

@@ -49,10 +49,12 @@ import org.springframework.boot.autoconfigure.jdbc.EmbeddedDataSourceConfigurati
 import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
 import org.springframework.boot.autoconfigure.orm.jpa.test.City;
 import org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration;
+import org.springframework.boot.jdbc.DataSourceBuilder;
 import org.springframework.boot.jdbc.DataSourceInitializationMode;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Primary;
 import org.springframework.jdbc.BadSqlGrammarException;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.jdbc.datasource.DataSourceTransactionManager;
@@ -233,6 +235,37 @@ class BatchAutoConfigurationTests {
 				});
 	}
 
+	@Test
+	void testBatchDataSource() {
+		this.contextRunner.withUserConfiguration(TestConfiguration.class, BatchDataSourceConfiguration.class)
+				.run((context) -> {
+					assertThat(context).hasSingleBean(BatchConfigurer.class)
+							.hasSingleBean(BatchDataSourceInitializer.class).hasBean("batchDataSource");
+					DataSource batchDataSource = context.getBean("batchDataSource", DataSource.class);
+					assertThat(context.getBean(BatchConfigurer.class)).hasFieldOrPropertyWithValue("dataSource",
+							batchDataSource);
+					assertThat(context.getBean(BatchDataSourceInitializer.class))
+							.hasFieldOrPropertyWithValue("dataSource", batchDataSource);
+				});
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	protected static class BatchDataSourceConfiguration {
+
+		@Bean
+		@Primary
+		public DataSource normalDataSource() {
+			return DataSourceBuilder.create().url("jdbc:hsqldb:mem:normal").username("sa").build();
+		}
+
+		@BatchDataSource
+		@Bean
+		public DataSource batchDataSource() {
+			return DataSourceBuilder.create().url("jdbc:hsqldb:mem:batchdatasource").username("sa").build();
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class EmptyConfiguration {
 

spring-boot-project/spring-boot-docs/src/main/asciidoc/howto.adoc

@@ -2429,8 +2429,12 @@ other factory that your application defines, if any.
 
 This section answers questions that arise from using Spring Batch with Spring Boot.
 
-NOTE: By default, batch applications require a `DataSource` to store job details. If you
+NOTE: By default, batch applications require a `DataSource` to store job details.
-want to deviate from that, you need to implement `BatchConfigurer`. See
+Batch autowires a single `DataSource` in your context and
+uses that for processing. If you like to use a different `DataSource`, you can create
+one and mark it is `@Bean` as `@BatchDataSource`. If you do so and want two data sources,
+remember to create another one and mark it as `@Primary`. If you want to deviate from that,
+ you need to implement `BatchConfigurer`. See
 {spring-batch-javadoc}/core/configuration/annotation/EnableBatchProcessing.html[The
 Javadoc of `@EnableBatchProcessing`] for more details.