How to java-configure separate datasources for spring batch data and business data? Should I even do it?

Question

My main job does only read operations and the other one does some writing but on MyISAM engine which ignores transactions, so I wouldn't require necessarily transaction support. How can I configure Spring Batch to have its own datasource for the JobRepository, separate from the one holding the business data? The initial one datasource-configurations is done like the following:

@Configuration
public class StandaloneInfrastructureConfiguration {

    @Autowired
    Environment env;

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
      LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
      em.setDataSource(dataSource());
      em.setPackagesToScan(new String[] { "org.podcastpedia.batch.*" });

      JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
      em.setJpaVendorAdapter(vendorAdapter);
      em.setJpaProperties(additionalJpaProperties());

      return em;
    }

    Properties additionalJpaProperties() {
          Properties properties = new Properties();
          properties.setProperty("hibernate.hbm2ddl.auto", "none");
          properties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect");
          properties.setProperty("hibernate.show_sql", "true");

          return properties;
    }

    @Bean
    public DataSource dataSource(){

       return DataSourceBuilder.create()
                .url(env.getProperty("db.url"))
                .driverClassName(env.getProperty("db.driver"))
                .username(env.getProperty("db.username"))
                .password(env.getProperty("db.password"))
                .build();          
    }

    @Bean
    public PlatformTransactionManager transactionManager(EntityManagerFactory emf){
      JpaTransactionManager transactionManager = new JpaTransactionManager();
      transactionManager.setEntityManagerFactory(emf);

      return transactionManager;
    }
}

and then it is imported in the Job's configuration class where the @EnableBatchProcessing annotation automagically makes use of it. My initial thought was to try to set the configuration class extend the DefaultBatchConfigurer, but then I get a

BeanCurrentlyInCreationException ( org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name jobBuilders: Requested bean is currently in creation: Is there an unresolvable circular reference?):

@Configuration
@EnableBatchProcessing
@Import({StandaloneInfrastructureConfiguration.class, NotifySubscribersServicesConfiguration.class})
public class NotifySubscribersJobConfiguration extends DefaultBatchConfigurer {

    @Autowired
    private JobBuilderFactory jobBuilders;

    @Autowired
    private StepBuilderFactory stepBuilders;

    @Autowired
    private DataSource dataSource;

    @Autowired
    Environment env;

    @Override
    @Autowired
    public void setDataSource(javax.sql.DataSource dataSource) {
        super.setDataSource(batchDataSource());
    }

    private DataSource batchDataSource(){          
       return DataSourceBuilder.create()
                .url(env.getProperty("batchdb.url"))
                .driverClassName(env.getProperty("batchdb.driver"))
                .username(env.getProperty("batchdb.username"))
                .password(env.getProperty("batchdb.password"))
                .build();          
    } 

    @Bean
    public ItemReader<User> notifySubscribersReader(){

        JdbcCursorItemReader<User> reader = new JdbcCursorItemReader<User>();
        String sql = "select * from users where is_email_subscriber is not null";

        reader.setSql(sql);
        reader.setDataSource(dataSource);
        reader.setRowMapper(rowMapper());       

        return reader;
    }
........
}   

Any thoughts are more than welcomed. The project is available on GitHub - https://github.com/podcastpedia/podcastpedia-batch

Thanks a bunch.

Answer 1

Ok, this is strange but it works. Moving the datasources to it's own configuration class works just fine and one is able to autowire.

The example is a multi-datasource version of Spring Batch Service Example:

DataSourceConfiguration:

public class DataSourceConfiguration {

    @Value("classpath:schema-mysql.sql")
    private Resource schemaScript;

    @Bean
    @Primary
    public DataSource hsqldbDataSource() throws SQLException {
        final SimpleDriverDataSource dataSource = new SimpleDriverDataSource();
        dataSource.setDriver(new org.hsqldb.jdbcDriver());
        dataSource.setUrl("jdbc:hsqldb:mem:mydb");
        dataSource.setUsername("sa");
        dataSource.setPassword("");
        return dataSource;
    }

    @Bean
    public JdbcTemplate jdbcTemplate(final DataSource dataSource) {
        return new JdbcTemplate(dataSource);
    }

    @Bean
    public DataSource mysqlDataSource() throws SQLException {
        final SimpleDriverDataSource dataSource = new SimpleDriverDataSource();
        dataSource.setDriver(new com.mysql.jdbc.Driver());
        dataSource.setUrl("jdbc:mysql://localhost/spring_batch_example");
        dataSource.setUsername("test");
        dataSource.setPassword("test");
        DatabasePopulatorUtils.execute(databasePopulator(), dataSource);
        return dataSource;
    }

    @Bean
    public JdbcTemplate mysqlJdbcTemplate(@Qualifier("mysqlDataSource") final DataSource dataSource) {
        return new JdbcTemplate(dataSource);
    }

    private DatabasePopulator databasePopulator() {
        final ResourceDatabasePopulator populator = new ResourceDatabasePopulator();
        populator.addScript(schemaScript);
        return populator;
    }
}

BatchConfiguration:

@Configuration
@EnableBatchProcessing
@Import({ DataSourceConfiguration.class, MBeanExporterConfig.class })
public class BatchConfiguration {

    @Autowired
    private JobBuilderFactory jobs;

    @Autowired
    private StepBuilderFactory steps;

    @Bean
    public ItemReader<Person> reader() {
        final FlatFileItemReader<Person> reader = new FlatFileItemReader<Person>();
        reader.setResource(new ClassPathResource("sample-data.csv"));
        reader.setLineMapper(new DefaultLineMapper<Person>() {
            {
                setLineTokenizer(new DelimitedLineTokenizer() {
                    {
                        setNames(new String[] { "firstName", "lastName" });
                    }
                });
                setFieldSetMapper(new BeanWrapperFieldSetMapper<Person>() {
                    {
                        setTargetType(Person.class);
                    }
                });
            }
        });
        return reader;
    }

    @Bean
    public ItemProcessor<Person, Person> processor() {
        return new PersonItemProcessor();
    }

    @Bean
    public ItemWriter<Person> writer(@Qualifier("mysqlDataSource") final DataSource dataSource) {
        final JdbcBatchItemWriter<Person> writer = new JdbcBatchItemWriter<Person>();
        writer.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<Person>());
        writer.setSql("INSERT INTO people (first_name, last_name) VALUES (:firstName, :lastName)");
        writer.setDataSource(dataSource);
        return writer;
    }

    @Bean
    public Job importUserJob(final Step s1) {
        return jobs.get("importUserJob").incrementer(new RunIdIncrementer()).flow(s1).end().build();
    }

    @Bean
    public Step step1(final ItemReader<Person> reader,
            final ItemWriter<Person> writer, final ItemProcessor<Person, Person> processor) {
        return steps.get("step1")
                .<Person, Person> chunk(1)
                .reader(reader)
                .processor(processor)
                .writer(writer)
                .build();
    }
}