Auto-Configuration for Cassandra does not back off if a custom ReactiveSessionFactory is defined

[tszmytka]

Hi, this is a first-timers-only issue. This means we've worked to make it more legible to folks who either haven't contributed to our codebase before, or even folks who haven't contributed to open source before.

If that's you, we're interested in helping you take the first step and can answer questions and help you out as you do. Note that we're especially interested in contributions from people from groups underrepresented in free and open source software!

If you have contributed before, consider leaving this one for someone new, and looking through our general ideal-for-contribution issues. Thanks!

Problem

The auto-configuration for Cassandra defines a ReactiveSessionFactory but does not check if the user has configured its own. The lack of check also means that the auto-configuration would potentially overrides the user's decision. Since Spring Boot works by default with bean overriding disabled, creating your own ReactiveSessionFactory leads to:

2020-06-07 15:26:34,604 DEBUG o.s.b.d.LoggingFailureAnalysisReporter [main] Application failed to start due to an exception
org.springframework.beans.factory.support.BeanDefinitionOverrideException: Invalid bean definition with name 'reactiveCassandraSessionFactory' defined in class path resource [org/springframework/boot/autoconfigure/data/cassandra/CassandraReactiveDataAutoConfiguration.class]: Cannot register bean definition [Root bean: class [null]; scope=; abstract=false; lazyInit=null; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveDataAutoConfiguration; factoryMethodName=reactiveCassandraSessionFactory; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/data/cassandra/CassandraReactiveDataAutoConfiguration.class]] for bean 'reactiveCassandraSessionFactory': There is already [Root bean: class [null]; scope=; abstract=false; lazyInit=null; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=cassandraConfig; factoryMethodName=reactiveCassandraSessionFactory; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [dev/tomek/data-cassandra/sampleapplication/persistence/CassandraConfig.class]] bound.
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.registerBeanDefinition(DefaultListableBeanFactory.java:943) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForBeanMethod(ConfigurationClassBeanDefinitionReader.java:286) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:144) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:120) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:331) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:236) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:280) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:96) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:706) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
	at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:62) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE]
	at dev.tomek.data-cassandra.sampleapplication.Sampleapplication.main(Sampleapplication.java:16) [main/:?]

Solution

The bean definition for reactiveCassandraSessionFactory should have a @ConditionalOnMissingBean so that it is not created if a bean of that type already exists.

Steps to Fix

• Claim this issue with a comment below and ask any clarifying questions you need
• Set up a repository locally following the Contributing Guidelines
• Try to fix the issue following the steps above
• Commit your changes and start a pull request.

[flinden68]

I want to have a look at this issue. Good opportunity to set up everything as described in Contributing Guidelines

[tszmytka]

Hi @flinden68
Sorry but I already claimed this. I wrote this in the initial message but it got deleted while rephrasing by @snicoll
The issue was only to confirm my solution proposal.

@snicoll Could you please assign the issue to me? Or is such a note enough?

[flinden68]

@snicoll Is the solution by adding only @ConditionalOnMissingBean to the bean? Seems too easy

[flinden68]

@tszmytka No problem, just fix it. I will wait for another one

[snicoll]

Fair enough @tszmytka. I've turn this as a first timer to let folks who never contributed to OSS to give it a go but you're right you've offered to help when you raised the issue. It's all yours.

[snicoll]

Closing in favor of PR #21769