Can not start spring application with webflux and websocket for ObjectPostProcessor is needed.

[Ayden-Franklin]

Summary

***************************
APPLICATION FAILED TO START
***************************

Description:

A component required a bean of type 'org.springframework.security.config.annotation.ObjectPostProcessor' that could not be found.

Action:

Consider defining a bean of type 'org.springframework.security.config.annotation.ObjectPostProcessor' in your configuration.

Configuration

@Configuration
@EnableWebFluxSecurity
public class WebSecurityConfig {
    @Bean
    public SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) {
       ...
    }
   ...
}

@Configuration
public class WebSocketConfiguration {
    @Bean
    public HandlerMapping handlerMapping() {
        Map<String, WebSocketHandler> map = new HashMap<>();
        map.put("/websocket", new WebSocketMessageHandler());
        SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping();
        mapping.setUrlMap(map);
        mapping.setOrder(-1); // before annotated controllers
        return mapping;
    }

    @Bean
    public WebSocketHandlerAdapter handlerAdapter() {
        return new WebSocketHandlerAdapter();
    }
}

Version

spring boot 2.0.5.RELEASE
io.spring.platform:platform-bom:Cairo-SR4
org.springframework.cloud:spring-cloud-dependencies:Finchley.SR1

dependencies

...
compile("org.springframework.boot:spring-boot-starter-actuator")
compile("org.springframework.boot:spring-boot-starter-security")
compile("org.springframework.boot:spring-boot-starter-websocket")
...

Solution

I tried again and found that it works well while using dependency of 'org.springframework:spring-websocket' instead of 'org.springframework.boot:spring-boot-starter-websocket'. In deed, spring-boot-starter-websocket depends on 'org.springframework:spring-webmvc' to case this issue. We can exclude 'org.springframework:spring-webmvc' to avoid it.

I suggest that spring-boot-starter-websocket does not depends on 'org.springframework:spring-webmvc' or there is another spring-boot-starter-webflux-websocket which depends on 'org.springframework:spring-webflux' instead of 'org.springframework:spring-webmvc'.

[wilkinsona]

Thanks for the suggestion, but we don’t want to make any changes to the structure of the starters. We’ve improved the documentation in #14069.

[Ayden-Franklin]

Thanks for your respond. But I don't know why you think you won't want to change the pom. Spring users should use 'org.springframework.boot:spring-boot-starter-websocket' but need excluding 'org.springframework:spring-webmvc'. It is not a good idea, I think.
Is there any necessary components in the spring-webmvc for spring-boot-starter-websocket?

[wilkinsona]

We don't want to change it because we don't want to have more starters than we need and we try to compose starters as much as possible. spring-boot-starter-web provides many components that are useful for the vast majority of applications building on the Servlet stack that want to use WebSockets. That includes spring-webmvc as, in our experience, it's unusual for a web application to only being using WebSockets.

[Ayden-Franklin]

Oh, sorry. I didn't mean a web application to only being using WebSockets. I meant an application using websocket with webflux but not webmvc. I agree that spring-boot-starter-web provides many components. I know, for reactive stack we may do more as it comes later (after spring mvc). So you don't want change the spring-boot-starter-web to exclude spring-webmvc.

Any way, thanks a lot for your so great framework.

[Ayden-Franklin]

By the way, I can't find any section to describe this important point. If a user starts a spring application depending on webflux, spring-security and spring-boot-starter-websocket but forgets to exclude spring-mvc they will get failure.

[bclozel]

@macrame We did improve documentation on that in the issue duplicating this one. See: https://docs.spring.io/spring-boot/docs/2.1.0.RELEASE/reference/html/boot-features-websockets.html