Provide an easy way to disable DataSourceInitializerInvoker

[galingerv]

Hi team!

I am developing a simple Spring Boot component that adds some DataSource beans to application context. Currently I am facing a problem with the way Spring Boot tries to implement the initialization of databases, i.e. the DataSourceInitializerInvoker bean that tries to retrieve primary bean of DataSource type during very first DataSource bean initialization.

That leads to a BeanCurrentlyInCreationException in my case, when @Primary DataSource bean is dependent on some other DataSource bean. The dependency cycle is as follows: "primary DataSource" -> "ordinary DataSource" -> "DataSourceInitializerInvoker" -> "primary DataSource".

A simple project that reproduces the problem can be found here - https://github.com/galingerv/datasource-issue-reproducer

I wonder if DataSourceInitializerInvoker can be turned off to avoid this problem, that would be acceptable in my case.

[philwebb]

Fixing the cycle issue might be hard to do in 2.2.x, but it would be nice to offer an easy way to switch off initialization.

[philwebb]

Actually @snicoll just reminded me that we already have a property. @galingerv have you tried adding spring.datasource.initialization-mode=never to your application.properties?

[galingerv]

@philwebb thanks for a quick response! Yes, I've tried that option with no success, and quick code analysis of version 2.2.6 shows me that that property is taking into consideration in the instance of internal class DataSourceInitializer that is created right after DataSourceinitializerInvoker bean retrieves the primary DataSource. So the cyclic dependency still exists. Even if we could analyse that property directly in DataSourceInitializerInvoker, I will have to override the default value of a property org.springframework.boot.autoconfigure.jdbc.DataSourceProperties#initializationMode to NEVER in my autoconfiguration which also seems to be tricky.

[snicoll]

@galingerv thanks for the feedback and sorry we sent you in the wrong direction. We should certainly improve that to make sure the bean is not registered at all if the property is set to never. I've created #21363 for that.

The current arrangement is that datasource initialization occurs regardless of if Spring Boot has configured the datasource, I think the most reasonable action at this point is to exclude DataSourceAutoConfiguration and eventually apply some of the things you may want (typically an import on DataSourcePoolMetadataProvidersConfiguration).

I will have to override the default value of a property org.springframework.boot.autoconfigure.jdbc.DataSourceProperties#initializationMode to NEVER in my autoconfiguration which also seems to be tricky.

Having an auto-configuration that provides multiple datasources is tricky I am afraid. This is a topic where an improvement in Spring Boot is required. Can you please give the exclude a try and report back?