Merge pull request #17375 from nosan

* gh-17375:
  Polish "Add support for configuring a Batch-specific DataSource"
  Add support for configuring a Batch-specific DataSource

Closes 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) {
-		return new BatchDataSourceInitializer(dataSource, resourceLoader, this.properties);
+	public BatchDataSourceInitializer batchDataSourceInitializer(DataSource dataSource,
+			@BatchDataSource ObjectProvider<DataSource> batchDataSource, ResourceLoader resourceLoader) {
+		return new BatchDataSourceInitializer(batchDataSource.getIfAvailable(() -> dataSource), resourceLoader,
+				this.properties);
 	}
 
 	@Bean

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

@@ -45,8 +45,10 @@ class BatchConfigurerConfiguration {
 
 		@Bean
 		BasicBatchConfigurer batchConfigurer(BatchProperties properties, DataSource dataSource,
+				@BatchDataSource ObjectProvider<DataSource> batchDataSource,
 				ObjectProvider<TransactionManagerCustomizers> transactionManagerCustomizers) {
-			return new BasicBatchConfigurer(properties, dataSource, transactionManagerCustomizers.getIfAvailable());
+			return new BasicBatchConfigurer(properties, batchDataSource.getIfAvailable(() -> dataSource),
+					transactionManagerCustomizers.getIfAvailable());
 		}
 
 	}
@@ -58,10 +60,11 @@ class BatchConfigurerConfiguration {
 
 		@Bean
 		JpaBatchConfigurer batchConfigurer(BatchProperties properties, DataSource dataSource,
+				@BatchDataSource ObjectProvider<DataSource> batchDataSource,
 				ObjectProvider<TransactionManagerCustomizers> transactionManagerCustomizers,
 				EntityManagerFactory entityManagerFactory) {
-			return new JpaBatchConfigurer(properties, dataSource, transactionManagerCustomizers.getIfAvailable(),
-					entityManagerFactory);
+			return new JpaBatchConfigurer(properties, batchDataSource.getIfAvailable(() -> dataSource),
+					transactionManagerCustomizers.getIfAvailable(), entityManagerFactory);
 		}
 
 	}

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

@@ -0,0 +1,42 @@
+/*
+ * 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;
+import org.springframework.context.annotation.Primary;
+
+/**
+ * Qualifier annotation for a DataSource to be injected into Batch auto-configuration. Can
+ * be used on a secondary data source, if there is another one marked as
+ * {@link Primary @Primary}.
+ *
+ * @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

@@ -2429,9 +2429,13 @@ 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
-want to deviate from that, you need to implement `BatchConfigurer`. See
-{spring-batch-javadoc}/core/configuration/annotation/EnableBatchProcessing.html[The
+NOTE: By default, batch applications require a `DataSource` to store job details.
+Batch autowires a single `DataSource` in your context and uses that for processing. To
+have Batch use a `DataSource` other than the application’s main `DataSource`, declare a
+`DataSource` bean, annotating its `@Bean` method with `@BatchDataSource`. If you do so and
+want two data sources, remember to create another one and mark it as `@Primary`. To take
+greater control, implement `BatchConfigurer`. See
+{spring-batch-javadoc}/core/configuration/annotation/EnableBatchProcessing.html[the
 Javadoc of `@EnableBatchProcessing`] for more details.
 
 For more about Spring Batch, see the https://projects.spring.io/spring-batch/[Spring Batch