[FIXED] What Is the Correct Way To Use AbstractReactiveWebInitializer

Issue

I've got a Spring WebFlux application running successfully as a standalone spring boot application.

I am attempting to run the same application in a Tomcat container, and following the documentation, I've created a class that extends AbstractReactiveWebInitializer. The class requires that I implement a method getConfigClasses that would return classes normally annotated with @Configuration. If the working spring boot app started with a class called ApplicationInitializer, then the resulting implementations would look like this:

@SpringBootApplication(scanBasePackages = "my.pkg")
@EnableDiscoveryClient
@EnableCaching
public class ApplicationInitializer {
    public static void main(String... args) {
        SpringApplication.run(ApplicationInitializer.class, args);
    }
}

and

public class ServletInitializer extends AbstractReactiveWebInitializer {
    @Override
    protected Class<?>[] getConfigClasses() {
        return new Class[] {ApplicationInitializer.class};
    }
}

When deployed, the only thing that starts is ApplicationInitializer, none of the autoconfigured Spring Boot classes (Cloud Config, DataSource, etc) ever kick off.

The documenation states this is the class I need to implement, I just expected the remainder of the spring environment to "just work".

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How should I be using this class to deploy a Reactive WebFlux Spring Boot application to a Tomcat container ?

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Edit:

After some additional research, I've narrowed it down to likely just Cloud Config. During bean post processing on startup, the ConfigurationPropertiesBindingPostProcessor should be enriched with additional property sources (from cloud config), but it appears to be the default Spring properties instead, with no additional sources.

The misisng properties is causing downstream beans to fail.

Solution

Spring Boot does not support WAR packaging for Spring WebFlux applications.

The documentation you're referring to is the Spring Framework doc; Spring Framework does support that use case, but without Spring Boot.

Answered By - Brian Clozel