Auto-configured WebClient no longer uses context's ReactorResourceFactory

[jorgegueyer]

Hi All!

After updating my project to Spring 3.5.4, the behaviour of my application has changed:

With Spring Boot 3.4.8, I could override the ReactorResourceFactory bean and to provide my custom implementation to create a Reactor Http Client. With the new version (Spring Boot 3.5.4), this component isn't used in any way, even though the Spring Boot configuration provides a default bean. Also, the documentation the both versions
say the ReactorResourceFactory bean can be override by developers:

• Spring Boot 3.5 - Calling REST Services
• Spring Boot 3.4 - Calling REST Services

I provide a sample to show this problem: https://github.com/jorgegueyer/reactor-resource-factory-issue

To reproduce the problem, the class ReactorResourceFactoryIssueApplicationTests must be executed with the different versions of Spring Boot defined in the pom.xml.

The test class provides a configuration class to overwrite the ReactorResourceFactory default bean with a custom implementation where we add some traces when the getLoopResources() and getConnectionProvider() method are invoked.

Using the version 3.4.8, we can see the following traces in the console:

ReactorResourceFactoryIssueApplicationTests in 1.415 seconds (process running for 2.459)
Getting the ConnectionProvider
Getting the LoopResources

Using the version 3.5.4 this traces don't appear.

[wilkinsona]

Thanks for reporting this. It's a regression from 3.4.x due to the context's ReactorResourceFactory not being used when creating the underlying Reactor Netty-based client. We'll work on a fix. In the meantime, you can work around the problem with the following bean:

@Bean
ClientHttpConnectorBuilderCustomizer<ReactorClientHttpConnectorBuilder> customizer(ReactorResourceFactory reactorResourceFactory) {
    return (builder) -> builder.withReactorResourceFactory(reactorResourceFactory);
}

[jorgegueyer]

Thanks for reporting this. It's a regression from 3.4.x due to the context's ReactorResourceFactory not being used when creating the underlying Reactor Netty-based client. We'll work on a fix. In the meantime, you can work around the problem with the following bean:

@bean
ClientHttpConnectorBuilderCustomizer customizer(ReactorResourceFactory reactorResourceFactory) {
return (builder) -> builder.withReactorResourceFactory(reactorResourceFactory);
}

Thanks for your replay. I will keep an eye on the new version. :)

[nosan]

I've prepared a fix in my branch 3.5.x...nosan:46658. However, I'm not sure whether applying withReactorResourceFactory in both org.springframework.boot.autoconfigure.web.reactive.function.client.ClientHttpConnectorAutoConfiguration and org.springframework.boot.autoconfigure.http.client.reactive.ClientHttpConnectorAutoConfiguration is the correct fix for 3.5.x.

[wilkinsona]

Thanks, @nosan. While I don't think it will do much harm to apply it in both places, I don't think it's necessary. We can leave org.springframework.boot.autoconfigure.web.reactive.function.client.ClientHttpConnectorAutoConfiguration to focus on applying the deprecated ReactorNettyHttpClientMapper instances as per its class javadoc and only configure the resource factory in org.springframework.boot.autoconfigure.http.client.reactive.ClientHttpConnectorAutoConfiguration.

[nosan]

My main concern is that the deprecated auto-configuration imports @Import(ReactorResourceFactoryConfiguration.class) but does not use it in any way, which seems a bit confusing.

[wilkinsona]

Like the unused ReactorResourceFactory reactorResourceFactory parameter, I think that's just the remnants of the previous arrangement and can be removed. The deprecated auto-configuration will do very little without the new auto-configuration as the customizer won't be called. I can't imagine a scenario where someone would exclude the new auto-configuration and still expect a Reactor-based client to be set up.

[wilkinsona]

Closing in favor of #46673. Thanks for the PR, @nosan.