Need to configure my JPA layer to use a TransactionManager (Spring Cloud Task + Batch register a PlatformTransactionManager unexpectedly) - spring-boot

Question

I am using Spring Cloud Task + Batch in a project.
I plan to use different datasources for business data and Spring audit data on the task. So I configured something like:
#Bean
public TaskConfigurer taskConfigurer() {
return new DefaultTaskConfigurer(this.singletonNotExposedSpringDatasource());
}
#Bean
public BatchConfigurer batchConfigurer() {
return new DefaultBatchConfigurer(this.singletonNotExposedSpringDatasource());
}
whereas main datasource is autoconfigured through JpaBaseConfiguration.
The problem comes when SimpleBatchConfiguration+DefaultBatchConfigurer expose a PlatformTransactionManager bean, since JpaBaseConfiguration has a #ConditionalOnMissingBean on PlatformTransactionManager. Therefore Batch's PlatformTransactionManager, binded to the spring.datasource takes place.
So far, this seems to be caused because this bug
So I tried to emulate what JpaBaseConfiguration does, defining my own PlatformTransactionManager over my biz datasource/entityManager.
#Primary
#Bean
public PlatformTransactionManager appTransactionManager(final LocalContainerEntityManagerFactoryBean appEntityManager) {
JpaTransactionManager transactionManager = new JpaTransactionManager();
transactionManager.setEntityManagerFactory(appEntityManager.getObject());
this.appTransactionManager = transactionManager;
return transactionManager;
}
Note I have to define it with a name other than transactionManager, otherwise Spring finds 2 beans and complains (unregardless of #Primary!)
But now it comes the funny part. When running the tests, everything runs smooth, tests finish and DDLs are properly created for both business and Batch/Task's databases, database reads work flawlessly, but business data is not persisted in my testing database, so final assertThats fail when counting. If I #Autowire in my test PlatformTransactionManager or ÈntityManager, everything indicates they are the proper ones. But if I debug within entityRepository.save, and execute org.springframework.transaction.interceptor.TransactionAspectSupport.currentTransactionStatus(), it seems the DatasourceTransactionManager from Batch's configuration is overriding, so my custom exposed PlatformTransactionManager is not being used.
So I guess it is not a problem of my PlatformManager being the primary, but that something is configuring my JPA layer TransactionInterceptor to use the non primary but transactionManager named bean of Batch.
I also tried with making my #Configuration implement TransactionManagementConfigurer and override PlatformTransactionManager annotationDrivenTransactionManager() but still no luck
Thus, I guess what I am asking is whether there is a way to configure the primary TransactionManager for the JPA Layer.

Answer 1

The problem comes when SimpleBatchConfiguration+DefaultBatchConfigurer expose a PlatformTransactionManager bean,
As you mentioned, this is indeed what was reported in BATCH-2788. The solution we are exploring is to expose the transaction manager bean only if Spring Batch creates it.
In the meantime you can set the property spring.main.allow-bean-definition-overriding=true to allow bean definition overriding and set the transaction manager you want Spring Batch to use with BatchConfigurer#getTransactionManager. In your case, it would be something like:
#Bean
public BatchConfigurer batchConfigurer() {
return new DefaultBatchConfigurer(this.singletonNotExposedSpringDatasource()) {
#Override
public PlatformTransactionManager getTransactionManager() {
return new MyTransactionManager();
}
};
}
Hope this helps.