Auto-configuration and ownership boundaries

What the auto-configuration does

The module’s AutoConfiguration.imports registers only ReactiveMongoAutoConfiguration. It creates ReactiveMongoTemplate when ReactiveMongoOperations is on the classpath and no bean of that type exists.

@AutoConfiguration
@ConditionalOnClass(ReactiveMongoOperations::class)
class ReactiveMongoAutoConfiguration {
    @Bean
    @ConditionalOnMissingBean(ReactiveMongoOperations::class)
    fun reactiveMongoTemplate(
        databaseFactory: ReactiveMongoDatabaseFactory,
        mongoConverter: MongoConverter,
    ): ReactiveMongoTemplate =
        ReactiveMongoTemplate(databaseFactory, mongoConverter)
}

It does not create the ReactiveMongoDatabaseFactory or MongoConverter. The fallback cannot be completed unless both beans are already available.

A typical Spring Boot application

Spring Boot’s reactive MongoDB auto-configuration normally supplies ReactiveMongoOperations. The bluetape4k fallback then backs off because of @ConditionalOnMissingBean. It also backs off when the application registers its own ReactiveMongoTemplate.

Adding this artifact therefore does not create a second client or pool. Use the condition evaluation report to inspect the actual bean graph.

Responsibility map

Layer	Owned responsibilities
bluetape4k module	Coroutine extensions, query DSL, template fallback
Spring Boot and Spring Data	Property binding, factory, mapping converter, template, lifecycle integration
Application	Custom conversions, auditing, index policy, transactions, domain repositories
MongoDB driver	Connection pool, server selection, protocol, sessions, concerns, timeouts

The presence of MongoDB Kotlin driver dependencies in the build does not move driver configuration into bluetape4k auto-configuration.

Custom conversion and auditing

The 1.11.0 source has no MongoCustomConversions bean and does not enable MongoDB auditing. Applications that need them should use a separate configuration.

@Configuration(proxyBeanMethods = false)
@EnableMongoAuditing
class MongoDomainConfiguration {
    @Bean
    fun mongoCustomConversions(): MongoCustomConversions =
        MongoCustomConversions.create { adapter ->
            adapter.registerConverter(MoneyWriteConverter())
        }
}

A converter changes the stored wire format. Verify that old and new application versions can read the same documents before a rolling deployment.

Source and tests

• ReactiveMongoAutoConfiguration.kt
• AutoConfiguration.imports
• MongoTestApplication.kt
• Module build

Next chapter

Use the configured template in Coroutine reads and cardinality.