Introduce @BatchTransactionManager to make it easier to configure Spring Batch to use a custom transaction manager

[nightswimmings]

Same as BatchAutconfiguration uses @BatchDatasource to tell apart the batch datasource from the main domain one, it should happen something similar to TransactionManager, or either build it by default over the passed @BatchDatasource

I would be tempted to think this is a batch issue in https://github.com/spring-projects/spring-batch/blob/11e653287f51a3c495a836cc0646ee58daea9fbf/spring-batch-core/src/main/java/org/springframework/batch/core/configuration/support/DefaultBatchConfiguration.java, but I can understand they don't want to provide defaults, but just expect the superior level to do so

Another option is some kind of Atomikos or old ChainedTransactionManager chaining

Is there any workaround right now in latest Boot to configure an independent Batch stack (transactionmanager,emf,datasource) on a regular Boot service that already expects an autoconfigured conventional domain database ?

[wilkinsona]

Is there any workaround right now in latest Boot to configure an independent Batch stack

You can provide your own sub-class of DefaultBatchConfiguration. That will make Boot's auto-configuration back off, allowing you to configure Batch with the DataSource and TransactionManager that meet your needs.

[nightswimmings]

Thanks Andy! Still, besides my individual issue, I think the default for the transactionmanager should be different if @BatchDatasource is present.

[wilkinsona]

WDYT, @fmbenhassine? Should we introduce @BatchTransactionManager alongside the existing @BatchDataSource? We decided not to do so last year but I'm not opposed to the idea. It would make it easier for users to configure Batch with a custom DB and transaction manager, removing the need for them to extends DefaultBatchConfiguration.

[nightswimmings]

Or perhaps autoconfigure the TransactionManager according to a possible @BatchDatasource like DefaultBatchConfigurer did.

        if(getTransactionManager() == null) {
		logger.warn("No transaction manager was provided, using a DataSourceTransactionManager");
		this.transactionManager = new DataSourceTransactionManager(this.dataSource);
	}

also

             if(dataSource == null) {
	      logger.warn("No datasource was provided...using a Map based JobRepository");
  
	      if(getTransactionManager() == null) {
		      logger.warn("No transaction manager was provided, using a ResourcelessTransactionManager");
		      this.transactionManager = new ResourcelessTransactionManager();
	      }

What we almost certain don't want ever is using the context/domain TransacionManager if you are takeing the trouble of defining a @BatchDatasource, IMO

[fmbenhassine]

@wilkinsona I am not opposed to adding @BatchTransactionManager neither. IIRC from our last discussion, the concern was how to make sure the datasource and transaction manager are aligned. But if the Boot defaults ensure that and the docs clearly mention what is expected from the user with regard to that alignment when overriding the defaults, then this new annotation would indeed make the configuration of Batch more straightforward.

[scottfrederick]

Closing in favor of #39473